summer flounder, life history and habitat characteristics

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NOAA Technical Memorandum NMFS-NE-151

Essential Fish Habitat Source Document:

Summer Flounder, Paralichthys dentatus,

Life History and Habitat Characteristics

U. S. DEPARTMENT OF COMMERCENational Oceanic and Atmospheric Administration

National Marine Fisheries ServiceNortheast Region

Northeast Fisheries Science CenterWoods Hole, Massachusetts

September 1999

Recent Issues

105. Review of American Lobster (Homarus americanus) Habitat Requirements and Responses to Contaminant Exposures.By Renee Mercaldo-Allen and Catherine A. Kuropat. July 1994. v + 52 p., 29 tables. NTIS Access. No. PB96-115555.

106. Selected Living Resources, Habitat Conditions, and Human Perturbations of the Gulf of Maine: Environmental andEcological Considerations for Fishery Management.. By Richard W. Langton, John B. Pearce, and Jon A. Gibson, eds.August 1994. iv + 70 p., 2 figs., 6 tables. NTIS Access. No. PB95-270906.

107. Invertebrate Neoplasia: Initiation and Promotion Mechanisms -- Proceedings of an International Workshop, 23 June1992, Washington, D.C. By A. Rosenfield, F.G. Kern, and B.J. Keller, comps. & eds. September 1994. v + 31 p., 8 figs.,3 tables. NTIS Access. No. PB96-164801.

108. Status of Fishery Resources off the Northeastern United States for 1994. By Conservation and Utilization Division,Northeast Fisheries Science Center. January 1995. iv + 140 p., 71 figs., 75 tables. NTIS Access. No. PB95-263414.

109. Proceedings ofthe Symposium on the Potential for Development of Aquaculture in Massachusetts: 15-17 February 1995,Chatham/EdgartownfDartmouth, Massachusetts. By Carlos A. Castro and Scott J. Soares, comps. & eds. January 1996.v + 26 p., 1 fig., 2 tables. NTIS Access. No. PB97-103782.

110. Length-Length and Length-Weight Relationships for 13 Shark Species from the Western North Atlantic. By Nancy E.Kohler, John G. Casey, Patricia A. Turner. May 1996. iv + 22 p., 4 figs., 15 tables. NTIS Access. No. PB97-135032.

111. Review and Evaluation of the 1994 Experimental Fishery in Closed Area II on Georges Bank. By Patricia A. Gerrior,Fredric M. Serchuk, Kathleen C. Mays, John F. Kenney, and Peter D. Colosi. October 1996. v + 52 p., 24 figs., 20 tables. NTISAccess. No. PB98-119159.

112. Data Description and Statistical Summary of the 1983-92 Cost-Earnings Data Base for Northeast U.S. CommercialFishing Vessels: A Guide to Understanding and Use of the Data Base. By Amy B. Gautam and Andrew W. Kitts. December1996. v + 21 p., I I figs., 14 tables. NTIS Access. No. PB97-169320.

113. Individual Vessel Behavior in the Northeast Otter Trawl Fleet during 1982-92. By Barbara Pollard Rountree. August 199Tv + 50 p., 1 fig., 40 tables. NTIS Access. No. PB99-169997.

114. U.S. Atlantic and Gulfof Mexico Marine Mammal Stock Assessments -- 1996. By Gordon T. Waring, Debra L. Palka, KeithD. Mullin, James H.W. Hain, Larry J. Hansen, and Kathryn D. Bisack. October 1997. viii + 250 p., 42 figs., 47 tables. NTISAccess. No. PB98-112345.

115. Status of Fishery Resources off the Northeastern United States for 1998. By Stephen H. Clark, ed. September 1998. vi+ 149 p., 70 figs., 80 tables. NTIS Access. No. PB99-129694.

116. U.S. Atlantic Marine Mammal Stock Assessments-- 1998. By Gordon T. Waring, Debra L. Palka, Phillip J. Clapham, StevenSwartz, Marjorie C. Rossman, Timothy V.N. Cole, Kathryn D. Bisack, and Larry J. Hansen. February 1999. vii + 182 p., 16figs., 56 tables. NTIS Access. No. PB99-134140.

117. Review of Distribution of the Long-finned Pilot Whale (Globicephala melas) in the North Atlantic and Mediterranean.By Alan A. Abend and Tim D. Smith. April 1999. vi + 22 p., 14 figs., 3 tables. NTIS Access. No. PB99-165029.

118. Tautog (Tautoga onifis) Life History and Habitat Requirements. By Frank W. Steimle and Patricia A. Shaheen. May 1999.vi + 23 p., 1 fig., I table. NTIS Access. No. PB99-16501 1.

119. Data Needs for Economic Analysis of Fishery Management Regulations. By Andrew W. Kitts and Scott R. Steinback.August 1999. iv + 48 p., 10 figs., 22 tables. NTIS Access. No. PB99-171456.

120. Marine Mammal Research Program of the Northeast Fisheries Science Center during 1990-95. By Janeen M. Quintal andTim D. Smith. September 1999. v + 28 p., 4 tables, 4 app. NTIS Access. No. PB2000-100809.

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7"o~M N T OfC

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NOAA Technical Memorandum NMFS-NE-151This series represents a secondary level of scientifiic publishing. All issues employthorough internal scientific review; some issues employ external scientific review.Reviews are -- by design -- transparent collegial reviews, not anonymous peer reviews.All issues may be cited in formal scientific communications.

Essential Fish Habitat Source Document:

Summer Flounder, Paralichthys dentatus,

Life History and Habitat Characteristics

David B. Packer, Sara J. Griesbach, Peter L. Berrien,

Christine A. Zetlin, Donna L. Johnson, and Wallace W. Morse

National Marine Fisheries Serv., James J. Howard Marine Sciences Lab., 74 Magruder Rd., Highlands, NJ 07732

U. S. DEPARTMENT OF COMMERCEWilliam Daley, Secretary

National Oceanic and Atmospheric AdministrationD. James Baker, Administrator

National Marine Fisheries ServicePenelope D. Dalton, Assistant Administrator for Fisheries

Northeast RegionNortheast Fisheries Science Center

Woods Hole, Massachusetts

September 1999

Editorial Notes on Issues 122-152in the

NOAA Technical Memorandum NMFS-NE Series

Editorial Production

For Issues 122-152, staff of the Northeast Fisheries Science Center's (NEFSC's) Ecosystems Processes Division havelargely assumed the role of staff of the NEFSC's Editorial Office for technical and copy editing, type composition, andpage layout. Other than the four covers (inside and outside, front and back) and first two preliminary pages, all preprintingeditorial production has been performed by, and all credit for such production rightfully belongs to, the authors andacknowledgees of each issue, as well as those noted below in "Special Acknowledgments."

Special Acknowledgments

David B. Packer, Sara J. Griesbach, and Luca M. Cargnelli coordinated virtually all aspects of the preprinting editorialproduction, as well as performed virtually all technical and copy editing, type composition, and page layout, of Issues122-152. Rande R. Cross, Claire L. Steimle, and Judy D. Berrien conducted the literature searching, citation checking,and bibliographic styling for Issues 122-152. Joseph J. Vitaliano produced all of the food habits figures in Issues 122-152.

Internet Availability

Issues 122-152 are being copublished, i.e., both as paper copies and as web postings. All web postings are, or will soonbe, available at: www.nefsc.nmfs.gov/nefsc/habitat/ejh. Also, all web postings will be in "PDF" format.

Information Updating

By federal regulation, all information specific to Issues 122-152 must be updated at least every five years. All officialupdates will appear in the web postings. Paper copies will be reissued only when and if new information associated withIssues 122-152 is significant enough to warrant a reprinting of a given issue. All updated and/or reprinted issues will retainthe original issue number, but bear a "Revised (Month Year)" label.

Species Names

The NMFS Northeast Region's policy on the use of species names in all technical communications is generally to followthe American Fisheries Society's lists of scientific and common names for fishes (i.e., Robinsetal. 199 1 a), mollusks (i.e.,Turgeon et al. 19 9 8b), and decapod crustaceans (i.e., Williams et al. 1989c), and to follow the Society for MarineMammalogy's guidance on scientific and common names for marine mammals (i.e., Rice 19 9 8d). Exceptions to this policyoccur when there are subsequent compelling revisions in the classifications of species, resulting in changes in the namesof species (e.g., Cooper and Chapleau 1998').

'Robins, C.R. (chair); Bailey, R.M.; Bond, C.E.; Brooker, J.R.; Lachner, E.A.; Lea, R.N.; Scott, W.B. 1991. Common and scientific names of fishes

from the United States and Canada. 5th ed. Amer. Fish. Soc. Spec. Publ. 20; 183 p.

'Turgeon, D.D. (chair); Quinn, J.F., Jr.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.;Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. 1998. Common and scientific names of aquaticinvertebrates from the United States and Canada: mollusks. 2nd ed. Amer. Fish. Soc. Spec. Publ. 26; 526 p.

'Williams, A.B. (chair); Abele, L.G.; Felder, D.L.; Hobbs, H.H., Jr.; Manning, R.B.; McLaughlin, P.A.; Pdrez Farfante, 1. 1989. Common andscientific names of aquatic invertebrates from the United States and Canada: decapod crustaceans. Amer. Fish. Soc. Spec. Publ. 17; 77 p.

'Rice, D.W. 1998. Marine mammals of the world: systematics and distribution. Soc. Mar. Mammal. Spec. Publ. 4; 231 p.

'Cooper, J.A.; Chapleau, F. 1998. Monophyly and interrelationships of the family Pleuronectidae (Pleuronectiformes), with a revised classification.Fish. Butl. (U.S.) 96:686-726.

Page iii

FOREWORD

One of the greatest long-term threats to the viability ofcommercial and recreational fisheries is the continuingloss of marine, estuarine, and other aquatic habitats.

Magnuson-Stevens Fishery Conservation andManagement Act (October 11, 1996)

The long-term viability of living marine resourcesdepends on protection of their habitat.

NMFS Strategic Plan for FisheriesResearch (February 1998)

The Magnuson-Stevens Fishery Conservation andManagement Act (MSFCMA), which was reauthorizedand amended by the Sustainable Fisheries Act (1996),requires the eight regional fishery management councils todescribe and identify essential fish habitat (EFH) in theirrespective regions, to specify actions to conserve andenhance that EFH, and to minimize the adverse effects offishing on EFH. Congress defined EFH as "those watersand substrate necessary to fish for spawning, breeding,feeding or growth to maturity." The MSFCMA requiresNMFS to assist the regional fishery management councilsin the implementation of EFH in their respective fisherymanagement plans.

NMFS has taken a broad view of habitat as the areaused by fish throughout their life cycle. Fish use habitatfor spawning, feeding, nursery, migration, and shelter, butmost habitats provide only a subset of these functions.Fish may change habitats with changes in life historystage, seasonal and geographic distributions, abundance,and interactions with other species. The type of habitat,as well as its attributes and functions, are important forsustaining the production of managed species.

The Northeast Fisheries Science Center compiled theavailable information on the distribution, abundance, andhabitat requirements for each of the species managed bythe New England and Mid-Atlantic Fishery ManagementCouncils. That information is presented in this series of30 EFH species reports (plus one consolidated methodsreport). The EFH species reports comprise a survey of theimportant literature as well as original analyses of fishery-

JAMES J. HOWARD MARINE SCIENCES LABORATORY

HIGHLANDS, NEW JERSEY

SEPTEMBER 1999

independent data sets from NMFS and several coastalstates. The species reports are also the source for thecurrent EFH designations by the New England and Mid-Atlantic Fishery Minagement Councils, and haveunderstandably begun to be referred to as the "EFH sourcedocuments."

NMFS provided guidance to the regional fisherymanagement councils for identifying and describing EFHof their managed species. Consistent with this guidance,the species reports present information on current andhistoric stock sizes, geographic range, and the period andlocation of major life history stages. The habitats ofmanaged species are described by the physical, chemical,and biological components of the ecosystem where thespecies occur. Information on the habitat requirements isprovided for each life history stage, and it includes, whereavailable, habitat and environmental variables that controlor limit distribution, abundance, growth, reproduction,mortality, and productivity.

Identifying and describing EFH are the first steps inthe process of protecting, conserving, and enhancingessential habitats of the managed species. Ultimately,NMFS, the regional fishery management councils, fishingparticipants, Federal and state agencies, and otherorganizations will have to cooperate to achieve the habitatgoals established by the MSFCMA.

A historical note: the EFH species reports effectivelyrecommence a series of reports published by the NMFSSandy Hook (New Jersey) Laboratory (now formallyknown as the James J. Howard Marine SciencesLaboratory) from 1977 to 1982. These reports, whichwere formally labeled as Sandy Hook LaboratoryTechnical Series Reports, but informally known as "SandyHook Bluebooks," summarized biological and fisheriesdata for 18 economically important species. The fact thatthe bluebooks continue to be used two decades after theirpublication persuaded us to make their successors - the 30EFH source documents - available to the public throughpublication in the NOAA Technical Memorandum NMFS-NE series.

JEFFREY N. CROSS, CHIEFECOSYSTEMS PROCESSES DIVISION

NORTHEAST FISHERIES SCIENCE CENTER

Page V

Contents

Introduction... ....................................................................................................................................................................L ife H istory and G eographical D istribution ................................................................................................................................ ; ............. 1Habitat Characteristics .................................................................................................................... 8S tatu s o f th e S to ck s ............................................................. ........................................................................................................ 20........ 2 0R e se arc h N e ed s ....................................................... : .............................................. : ............................................................................... 2 0A c k n o w le d g m e n ts ......................... : ......................................................................................................................................................... 2 1R e fe re n c e s C ite d ..... ...................................................................................................................... ........................................................ 2 1

Tables

Table 1. Presence of summer flounder inshore, by State, as documented by authors cited in the text and personal communications....29Table 2. Habitat parameters for summer flounder, Paralichthys dentatus: inshore New Jersey ...................................................... 32Table 3. Habitat parameters for summer flounder, Paralichthys dentatus: inshore Delaware ..... : ....................... 34Table 4. Habitat parameters for summer flounder, Paralichthys dentatus: inshore North Carolina ........................ 36Table 5. Summary of life history and habitat parameters for summer flounder: inshore New Jersey, Delaware and North Carolina ..... 40T able 6. Sum m er fl ounder catch and status ............. ............................................................................................................................... 42

Figures

Figure 1. The summer flounder, Paralichthys dentatus (from Goode 1884) ........................................................................................ 43Figure 2. Overall distribution of adult and juvenile summer flounder in NEFSC bottom trawl surveys ......................................... 44Figure 3. Distribution and abundance of juvenile and adult summer flounder collected during NEFSC bottom trawl surveys ........... 45Figure 4. Seasonal abundance of adult summer flounder relative to water depth based on NEFSC bottom trawl surveys ........ 47Figure 5. Distribution and abundance of adult summer flounder in Massachusetts coastal waters ............................................... 48Figure 6. Seasonal distribution and relative abundance of adult summer flounder collected in Narragansett Bay ......................... 49Figure 7. Seasonal length frequencies of summer flounder caught in Narragansett Bay .............................. 50Figure 8. Seasonal abundance of adult summer flounder relative to bottom depth based on Narragansett Bay trawl surveys ............. 51Figure 9. Distribution and abundance of juvenile and adult summer flounder collected in Long Island Sound ............... 52Figure 10. Length frequency distribution of juvenile and adult summer flounder collected in Long Island Sound .......................... 53Figure 11. Distribution and relative abundance of adult summer flounder collected in the Hudson-Raritan estuary ........................ 54Figure 12. Length-frequency distributions of juvenile and adult summer flounder from Newark Bay, New Jersey ......................... 55Figure 13. Distribution and abundance of juvenile and adult summer flounder in Pamlico Sound, North Carolina .............................. 56Figure 14. Distribution and abundance of summer flounder eggs collected during NEFSC MARMAP surveys ............................. 58Figure 15. Monthly abundance of summer flounder eggs by region from NEFSC MARMAP surveys ........................................... 60Figure 16. Abundance of summer flounder eggs relative to water depth based on NEFSC MARMAP surveys ............................. 61Figure 17. Distribution and abundance of summer flounder larvae collected during NEFSC MARMAP surveys .......................... 62Figure 18. Monthly abundance of summer flounder larvae by region from NEFSC MARMAP surveys ......................................... 65Figure 19. Abundance of summer flounder larvae relative to water depth based on NEFSC MARMAP surveys ............................. 66Figure 20. Classification of the transformation stages of summer flounder based on degree of eye migration ............................... 67Figure 21. Length frequency distributions for transforming larvae and juveniles collected from Charleston Harbor marsh creeks ....... 68Figure 22. Distribution and abundance of juvenile summer flounder in Massachusetts coastal waters ........................................... 69Figure 23. Seasonal abundance of juvenile summer flounder relative to water depth based on NEFSC bottom trawl surveys .............. 70Figure 24. Distribution and relative abundance of juvenile summer flounder collected in the Hudson-Raritan estuary ................... 71Figure 25. Monthly distribution of summer flounder in the Chesapeake Bay main stem and major Virginia tributaries ....... ......... 72Figure 26. Length frequency summary for summer flounder in the Chesapeake Bay main stem and major Virginia tributaries ........... 74Figure 27. Abundance of summer flounder eggs relative to water temperature based on NEFSC MARMAP surveys.................... 75Figure 28. Abundance of summer flounder larvae relative to water temperature based on NEFSC MARMAP surveys ................... 76Figure 29. Seasonal abundance of juvenile summer flounder relative to bottom temperature based on NEFSC trawl surveys ............. 77Figure 30. Abundance of juvenile and adults relative to bottom temperature and depth based on Massachusetts trawl surveys ........... 78Figure 31. Abundance of juvenile summer flounder relative to salinity in four Charleston Harbor, South Carolina marsh creeks ........ 79Figure 32. Relative importance of each diet item to summer flounder from the Newport and North Rivers, North Carolina ....... 80

Page vi

Figure 33. Food items in the seasonal diet of young summer flounder from the Neuse River and Pamlico Sound, North Carolina ...... 81Figure 34. Seasonal abundance of adult summer flounder relative to bottom temperature based on NEFSC bottom trawl surveys ...... 82Figure 35. Seasonal abundance of adult summer flounder relative to bottom temperature based on Narragansett Bay trawl surveys.. .83Figure 36. Abundance of the major prey items in the diet of summer flounder collected during NEFSC bottom trawl surveys ........... 84Figure 37. Commercial landings, NEFSC survey indices, and stock biomass for Georges Bank and Mid-Atlantic summer flounder ..86Figure 38. Distribution and abundance of adult and juvenile summer flounder during high and low abundance periods ................ 87

INTRODUCTION

The geographical range of the summer flounder orfluke, Paralichthys dentatus (Figure 1), encompasses theshallow estuarine waters and outer continental shelf fromNova Scotia to Florida (Ginsburg 1952; Bigelow andSchroeder 1953; Anderson and Gehringer 1965; Leim andScott 1966; Gutherz 1967; Gilbert 1986; Grimes et al.1989), although Briggs (1958) gives their southern range asextending into the northern Gulf of Mexico. The center ofits abundance lies within the Middle Atlantic Bight fromCape Cod, Massachusetts, to Cape Hatteras, North Carolina(Figure 2; Hildebrand and Schroeder 1928). North of CapeCod and south of Cape Fear, North Carolina, summerflounder numbers begin to diminish rapidly (Grosslein andAzarovitz 1982). South of Virginia, two closely relatedspecies, the southern flounder (Paralichthys lethostigma)and the gulf flounder (Paralichthys albigutta) occur andsometimes are not distinguished from summer flounder(Hildebrand and Cable 1930; Byme and Azarovitz 1982).For more detailed discussions of the summer flounder'sdistribution on the shelf and in the various estuaries, see theLife History and Geographical Distribution section.

Summer flounder exhibit strong seasonal inshore-offshore movements, although their movements are often notas extensive as compared to other highly migratory species.Adult and juvenile summer flounder normally inhabitshallow coastal and estuarine waters during the warmermonths of the year and remain offshore during the fall andwinter (Figure 3). Complete descriptions of the inshore-offshore migratory patterns of the summer flounder are inthe Life History and Geographical Distribution section ofthis paper.

LIFE HISTORY AND

GEOGRAPHICAL DISTRIBUTION

STOCK STRUCTURE

Several stocks of summer flounder may exist throughoutits range, and numerous attempts have been made to identifythem. Since a genetically distinct stock can have uniquerates of recruitment, growth, and mortality (Cushing 1981),identification of the various stocks or subpopulations ofsummer flounder and their stock-specific biological traits, aswell as their habitat distribution and overlap, is necessary forproper management. Previous stock identification studiessuggested that significant differences exist between summerflounder north and south of Cape Hatteras; i.e., betweenthose in the Mid-Atlantic Bight and South Atlantic Bight(Wilk et al. 1980; Fogarty et al. 1983; Able et al. 1990;Wenner et al. 1990a). Summer flounder north and south ofthe Cape were statistically separable on the basis ofmorphometric characters, with apparent intermixing ofnorthern and southern contingents in the vicinity of CapeHatteras [tagging studies by Desfosse (1995) also indicated

that there was some exchange of summer flounder betweenthe north and south of Cape Hatteras during winter]. Thus,it was suggested that the Cape Hatteras region may form azoogeographical barrier between the Middle and SouthAtlantic Bights which results in the reproductive isolation ofthe adjacent stocks of summer flounder (Wilk et al. 1980;Fogarty et al. 1983). This was also suggested by taggingstudies in the nearshore waters and sounds north of NorthCarolina which showed that fish tagged north of CapeHatteras moved northward, while fish tagged south ofHatteras moved southward (Monaghan 1992, 1996). Analternative hypothesis by Wenner et al. (1990a) suggestedthat, rather than two separate populations, the South AtlanticBight may serve as a nursery area for summer flounder inthe Mid-Atlantic Bight.

However, Jones and Quattro (1999) analyzed -thegenetic diversity revealed in the mitochondrial DNA(mtDNA) in samples of juveniles and adult summer floundercollected from coastal sites from Buzzard's Bay,Massachusetts to Charleston, South Carolina during 1992 to1996. In contrast to the previous morphological studies,analyses of mtDNA variation revealed no significantpopulation subdivision centered around Cape Hatteras; i.e.,summer flounder populations are not genetically differentnorth and south of Cape Hatteras. Jones and Quattro (1999)suggest that the phenotypic divergence seen amonggeographic samples of summer flounder (Wilk et al. 1980;Fogarty et al. 1983) may reflect differential environmentalinfluences.

Within the Middle Atlantic Bight, Fogarty et al. (1983)reported that a summer flounder discrimination workshopwas unable to examine adequately the hypothesis of multiplestocks. Although Smith (1973) identified concentrations ofsummer flounder eggs off Long Island, Delaware-Virginia,and North Carolina, the workshop concluded that thedistribution of summer flounder eggs and larvae wascontinuous throughout the Middle Atlantic Bight and thatthe apparent concentrations identified by Smith (1973) werenot the result of multiple stocks, but may have been due tosampling variability. However, Jones and Quattro (1999)did detect population genetic structure in their samples ofsummer flounder from the northern portion of its range; i.e.,a small but significant portion of the total genetic variancecould be attributed to differences between theirMassachusetts and Rhode Island samples and all the othersamples. Furthermore, tagging studies by Desfosse et al.(1988) and Desfosse (1995) indicate that there may be twosubpopulations of summer flounder in Virginia inshorewaters, and studies by Van Housen (1984), Delaney (1986),and Holland (1991), as well as such supplementalobservations as by Ross et al. (1990) off of North Carolina,suggest that inshore populations from Virginia to NorthCarolina may form a separate population from those to thenorth and offshore (a trans-Hatteras stock). Further studiesfrom these regions will be necessary to confirm theseobservations.

Nonetheless, it is important to note that throughout the

U.S. EEZ, summer flounder is managed and assessed as asingle stock' by the Mid-Atlantic Fishery ManagementCouncil (NMFS 1997).

ADULTS

As stated above, summer flounder exhibit strongseasonal inshore-offshore movements (Figure 3). Adultflounder normally inhabit shallow coastal and estuarinewaters during the warmer months of the year and remainoffshore during the colder months on the outer continentalshelf at depths down to 150 m (Figure 4; Bigelow andSchroeder 1953; Grosslein and Azarovitz 1982). Someevidence suggests that older adults may remain offshore allyear (Festa 1977). However, due to overfishing, most of theadults are < 3 years of age and they return to the innercontinental shelf and estuaries during the summer [Able andKaiser 1994; Terceiro 1995; Northeast Fisheries ScienceCenter .1997; in addition, Desfosse's (1995) study inVirginia waters notes that the majority of fish sampled from1987-1989 were from 0-3 years of age, and over 90% of thesummer flounder survey catch in Delaware Bay for 1996.was also less than age 3 (Michels 1997)]. The southernpopulation may undertake less extensive offshore migrations(Fogarty et al. 1983). Tagging studies indicate that fishwhich spend their summer in a particular bay tend largely toreturn to the same bay in the subsequent year or to move tothe north and east (Westman and Neville 1946; Hamer andLux 1962; Poole 1962; Murawski 1970; Lux and Nichy1981; Monaghan 1992; Desfosse 1995). For example,tagging studies indicate that the majority of summerflounder from inshore' New Jersey return to inshore NewJersey the following year. This homing is also evident insummer flounder which return to .New York waters, withsome movement to waters off Connecticut, Rhode Island andMassachusetts (Poole 1962). Once inshore during thesummer months, there appears to be very little movement ofinshore fish to offshore waters (Westman and Neville 1946;Poole 1962; Desfosse 1995).

Tagging studies conducted by Poole (1962) and Luxand Nichy (1981) on flounder released off Long Island andsouthern New England revealed that fish usually beganseaward migrations in September or October. Theirwintering grounds are located primarily between Norfolkand Veatch Canyons east of Virginia and Rhode Island,respectively, although they are known to migrate as farnortheastward as Georges Bank. Fish that move as far northas the wintering grounds north of Hudson Canyon maybecome rather permanent residents of the northern segmentof the Mid-Atlantic Bight (Lux and Nichy 198 1). New Yorkand New Jersey fish may move farther south in the wintermonths and generally may not move as far north in thesummer as New England flounder (Poole 1962).

The presence, distribution, and abundance of the adultsnearshore and in the estuaries has been documented by bothfishery dependent and independent data and each States'

flounder experts (Table 1). For example, summer flounderin Massachusetts migrate inshore in early May and occuralong the entire shoal area south of Cape Cod and BuzzardsBay, Vineyard Sound, Nantucket Sound, and the coastalwaters around Martha's Vineyard (Figure 5; Howe et al..1997). They also occur in the shoal waters in Cape Cod Bay(A.B. Howe, Massachusetts Div. of Mar. Fish., Sandwich,MA, personal communication). In some years summerflounder are found along the eastern side of Cape Cod andas far north as Provincetown by early May. TheMassachusetts Division of Marine Fisheries considers theshoal waters of Cape Cod Bay and the region east and southof Cape Cod, including all estuaries, bays and harborsthereof, as critically important habitat (Howe, personalcommunication). Summer flounder begin moving offshorein late September and October and Howe (personalcommunication) believes that spawning occurs withinterritorial waters south of Cape Cod 'because occasional ripeand running fish have been taken there. Summer flounderare regularly taken in southern Massachusetts waters as lateas December, presumably as fish are dispersing to offshorewintering grounds, which, in most years are well out on thecontinental shelf from approximately Veatch Canyon toBaltimore Canyon.

T.R. Lynch (Rhode Island Dept. of Environ. Mgmt.,Wickford, RI, personal communication) states that thecoastal waters of Rhode Island, the immediate waterssurrounding Block Island, and the waters of LittleNarragansett Bay and all of Narragansett Bay are habitat forboth adults and juveniles. Based on collections from the1990-1996 Rhode Island Narragansett Bay survey, adultswere distributed throughout the Bay and captured in allseasons except winter and most were caught in summer andautumn (Figure 6). The length frequencies show that similarsizes were captured in each season and lengths ranged fromabout 25-71 cm with most occurring from 30-50 cm (Figure7). Abundance in relation to bottom depth shows apreference for depths greater than 12.2-15.2 m (40-50 ft)and that few were captured in depths less than 9.1 m (30 ft)(Figure 8).

In Connecticut, E. Smith (Connecticut Dept. ofEnviron. Prot., Hartford, CT, personal communication)states that the flounder migrate to inshore waters in lateApril and early May, and are present in Long Island Soundthroughout the April-November trawl survey period, andprobably occur in limited numbers in winter as well (Figure9 -- these figures include juveniles and adults, see Figure10). August through October are often the months ofhighest relative abundance (Simpson et al. 1990a, b, 1991;Gottschall et al., in review). Although they occur on allbottom types, their abundance does vary by area and depth(Gottschall et al., in review). In April, abundance is similarat all depths, but from May through August abundance ishighest in shallow water, especially in depths less than 9 malong the Connecticut shore from New Haven to NianticBay, and near Mattituck, New York (Figure 9; Gottschall etal., in review). In September, when abundance peaks,

summer flounder are again distributed in all depthsthroughout the sound. After September, their abundancedecreases, and the remaining fish are more common indeeper water. Abundance is highest in depths between 18-27 m in October and depths > 27 m in November (Gottschallet al., in review). Abundance indices within the Sound aregeneially highest in the central Sound (Connecticut toHousatonic Rivers) and lowest west of the Housatonic River(Simpson et al. 1990a, b, 1991). Salinity range appears tobe at least 15 ppt and greater. The trawl survey usuallytakes 400-700 fish in 320 tows per year. In 1989, only 47fish were taken (D.G. Simpson, Connecticut Dept. ofEnviron. Prot., Waterford, CT, personal communication).From the Marine Angler Survey, about two-thirds of thesport flounder catch is from east of the Connecticut River,while the trawl survey catches indicate that the greater NewHaven area is also important.

In 'the Hudson-Raritan estuary, New York and NewJersey, summer flounder was the 13th most abundant speciesin the Wilk et al. (1977) survey and it occurred in 21% of alltrawls and had a mean annual density in the Lower Baycomplex of 1.2/15 min tow (see also reviews by Gaertner1976 and Berg and Levinton 1985). The 1992-1997Hudson-Raritan surveys show the adults to be present inmoderate numbers throughout the estuary in all seasonsexcept winter (Figure 11). In the fall, they tend to be foundin greater numbers in the deeper waters of the RaritanChannel (Figure I1). In the spring, the greatest numbersoccurred in Sandy Hook Bay. The greatest densities ofsummer flounder adults occurred in the summer, particularlyin the deeper Raritan and Chapel Hill channels and Raritanand Sandy Hook Bays. This species was not reported in anytrawls in the Arthur Kill-Hackensack River estuary.However, it has been collected in Newark Bay from April-October (Wilk et al. 1997; Figure 12). Great South Bay, onthe south shore of Long Island, supports an importantrecreational fishery, particularly around Fire Island inlet(Neville etal. 1939; Schreiber 1973). .

Tagging studies by Murawski (1970) providedrecaptured summer flounder from the entire New Jerseycoastline. Summer flounder overwinter offshore of NewJersey in 30-183 m of water. Allen et al. (1978) collectedboth adult and juvenile summer flounder in Hereford Inletnear Cape May. They occurred in all of the majorwaterways, but were more abundant in the upper embaymentfrom May to July and in the lower embayment from Augustto October. The majority were 200-400 mm and werecaught on the slopes of the channels. In Barnegat Bay, anichthyofauna survey by Vouglitois (1983) from 1976-1980found a wide range of sizes of summer flounder, but in lownumbers. This study was conducted along the westernshoreline of the Bay, where muddy sediments predominate,and Vouglitois (1983) suggests that the scarcity of summerflounder is due to their apparent preference for sandysubstrates. A hard sandy bottom does predominate in the

'eastern portion of the Bay and this is where most summerflounder have been caught.

Delaware Bay is an important nursery and summeringarea for adults as well as a nursery area for juveniles (R.Smith, Delaware Dept. of Nat. Res. and Environ. Control,Dover, DE, personal communication). They are abundant inthe lower and middle portions of the estuary, and rare in theupper estuary (Ichthyological Associates, Inc. 1980;Seagraves 1981; Weisberg et al. 1996; Michels 1997).Smith and Daiber (1977) caught adults from the shoreline toa maximum depth of 25 m, mostly from May throughSeptember, while R. Smith (personal communication) statesthat adults have been captured in Delaware Bay during allmonths of the year, but appear to be most common fromApril to November. The Delaware Bay Coastal FinfishAssessment Survey for 1996 found adults throughout theApril to December sampling period, with the highest catchrate in April and greatest occurrences at mid-bay stations(Michels 1997). Delaware's coastal bays are also used bysummer flounder as nursery and summering areas [e.g.,Indian River and Rehobeth Bays (Michels 1997)].

In Virginia adult flounder use theEastern Shore seasidelagoons and inlets and the lower Chesapeake Bay as summerfeeding areas (Schwartz 1961; J.A. Musick, Virginia Inst.Mar. Sci., Gloucester Point, VA, personal communication).These fish usually concentrate in shallow warm water at theupper reaches of the channels and larger tidal creeks on theEastern Shore in April, then move toward the inlets as springand summer progress. They are most abundant in the oceannear inlets by July and August. Tagging studies by Desfosse(1995) revealed that fall migration begins out of ChesapeakeBay in October and is completed by December where mostrecaptures of fish were from the nearshore fishery from CapeHenry south to Cape Hatteras. The majority of taggedreturns during January through March came from offshorefrom the Cigar north to Wilmington Canyon, and wereconcentrated east of Cape Henry from the Cigar to NorfolkCanyon. A second group came from inshore waters nearOregon Inlet, south to Cape Hatteras. Movement inshorestarted in March or perhaps as 'early as February, andcontinued from April till June.

Virginia's artificial reefs also provide additional habitatfor summer flounder (J. Travelstead, Virginia Mar. Res.Comm., Hampton, VA, personal communication; see alsoLucy and Barr 1994). Reef materials include discardedvessels, automobile tires, and fabricated concrete structures.

Both adults and juveniles occur in Pamlico Sound andadjacent estuaries (Figure 13), although it appears thatjuveniles are usually the more abundant, confirming thesignificant role of these estuaries as a nursery area for thisspecies (Powell and Schwartz 1977). They occur in areas ofintermediate or high salinities, often close to inlets, andprefer a sandy or sand/shell substrate (Powell and Schwartz1977).

Several surveys have shown that both adult and juvenilesummer flounder occur in small numbers in the waters ofSouth Carolina (e.g., Bearden and Farmer 1972; Hicks1972; Wenner et al. 1981, 1986; Stender and Martore 1990;Wenner et al. 1990a, b). Artificial reefs also provide habitat

for summer flounder off of South Carolina (Parker et al.1979).

Dahlberg (1972) surveyed the North and SouthNewport Rivers, Sapelo Sound, and the St. CatherinesSound estuarine complex in Georgia. Adult and juvenilesummer flounder were most abundant in the lower reachesof the estuaries and were rarely trawled in the middlereaches.

REPRODUCTION

In the Middle Atlantic Bight, Morse (1981) estimatedthe length at which 50% of the fish are mature (L50) is 24.6cm for males and 32.2 cm for females. The smallest maturemale was 19.1 cm and the largest immature male was 39.9cm. Females began maturing at 24.9 cm and the largestimmature female was 43.9 cm. The range of L50 for malesand females indicates sexual maturity is attained by age 2(Morse 1981; however see below). Adult females are 60mm total length (TL) longer on average than males at firstattainment of sexual maturity. The L5 0 also varied duringthe six years of Morse's (1981) study. No consistent generaltrend in L50 was evident as males and females appeared toexhibit independent changes. Murawski and Festa (1976)reported that the minimum size at maturity of femalesummer flounder sampled from off New Jersey during 1963-1964 was 37.0 cm TL, while Smith and Daiber (1977)reported that the minimum size at maturity of fish fromDelaware Bay was 30.5 cm and. 36.0 cm TL for males andfemales, respectively. Desfosse (1995) reported theminimum size at maturity of fish sampled from 1987-1989in Virginia waters was 22-23 cm TL for males and 23-24 cmTL for females. The Lyo for males was 26.1-27.0 cm TL and•36.1-37.0 cm TL for females. Powell (1974) noted that theminimum size at maturity of summer flounder from PamlicoSound, North Carolina was 35.0 cm TL. In the SouthAtlantic Bight, Wenner et al. (1990a) estimated the L5o to be28.9 cm TL for males and 30.7 cm TL for females,corresponding to fish approaching age 2. Based on thestudy by O'Brien et al. (1993) on the L50 of summerflounder sampled from 1985-1989 from Nova Scotia toCape Hatteras, this report will use the female size of 28 cm(age 2.5) as the divide between all juvenile and adultindividuals. The median length at maturity for males in theO'Brien et al. (1993) study was 24.9 cm (age 2). However,as O'Brien et al. (1993) notes, a revision to agingconvention (Smith et al. 1981; Almeida et al. 1992) hasresulted in median lengths being attained a year earlier thanthose reported above; thus, for example, the ages of O'Brienet al. (1993) are also off by a year (i.e., the age 2.5 femalefish are now age 1.5). These conclusions have beensupported by more recent growth studies (Able et al. 1990;Szedlmayer et al. 1992).

Fecundity and length exhibit a curvilinear relationship,but with logarithmic transformations, Morse (1981)expressed the relationship as:

loglo Fecundity = logl 0 a + b (log10 length)

where the intercept (a) = -3.098 and the slope (b) = 3.402.The relationship between fecundity and weight and ovaryweight were expressed by Morse (1981) as:

Fecundity =a + bX

where the intercept (aweight) = -101,865.5 and the slope(bweight) = 908.864, and the intercept (aova weight) -

52,515.161 and the slope (bovary weight) = 10,998.048.

Powell (1974) estimated that females ranging from50.6-68.2 cm TL have 1.67-1.70 million ova per fish, whileMorse (1981) reported fish between 36.6 and 68.0 cm TLhave 0.46-4.19 million ova. The relative fecundity, numberof eggs produced per gram of total weight of spawningfemale, ranged from 1,077-1,265 in Morse's (1981) study.The increase in variability in fecundity estimates as weightincreases tends to obscure the true relationship. The highegg production to body weight is. maintained by serialspawning. In fact, the weight of annual egg production,assuming an average egg diameter of 0.98 mm and 1.0specific gravity, equals' approximately 40-50% of thebiomass of spawning females (Morse 1981).

Morse (1981) calculated the percent of ovary weight tototal fish weight as an index for maturity. The meanmaturity index increased rapidly from August to September,

.peaked in October-November, then gradually decreased toa low in July. The wide range in the maturity indices duringthe spawning season indicates nonsynichronous maturationof females and a relatively extended spawning season. Thelength and peak spawning timeas indicated by the maturityindex agree with results determined by egg and larvaloccurrence (Herman 1963; Smith 1973).

Spawning occurs over the open ocean areas of the shelf(Figure 14). Summer flounder spawn during the fall andwinter while the fish are moving offshore or onto theirwintering grounds; the offshore migration is presumablykeyed to declining water temperature and decreasingphotoperiod during the autumn. The spawning migrationbegins near the peak of the summer flounder's gonadaldevelopment cycle, with the oldest and largest fish migratingfirst each year (Smith 1973).

The seasonal migratory/spawning pattern varies withlatitude (Smith 1973)"; i.e., gonadal development, spawningand offshore movements occur earlier in the northern part oftheir range (Rogers and Van Den Avyle 1983). Forexample, in Delaware Bay, gonads of summer flounderappear to ripen from mid-August through November (Smithand Daiber 1977), while peak gonadal development occursduring December and January for fish around Cape Hatteras(Powell 1974). Spawning begins in September in the inshorewaters of southern New England and the Mid-Atlantic. Asthe season progresses, spawning moves onto Georges Bankas well as southward and eastward into deeper waters acrossthe entire breadth of the shelf (Berrien and Sibunka 1999).

Spawning continues through December in the northernsections of the Middle Atlantic Bight, and throughFebruary/March in the southern sections (Smith 1973;Morse 1981; Almeida et al. 1992). Spawning peaks inOctober north of Chesapeake Bay and November south ofthe Bay (Smith 1973; Able et al. 1990; note that the latterstatement on spawning south of the Bay in Novemberappears to contradict the published information aboveconcerning peak gonadal development occurring December-January near Cape Hatteras). The half year spawning seasonreduces larval crowding and decreases the impact ofpredators and adverse environmental conditions on egg andlarval survival (Morse 1981). In the South Atlantic Bight,maturity observations by Wenner et al. (1990a) suggest thatspawning begins as early as October, and may continuethrough February and possibly early March.

EGGS

Eggs of summer flounder are pelagic and buoyant. Theyare spherical with a transparent, rigid shell; yolk occupiesabout 95% of the egg volume. Mean diameter of matureunfertilized eggs is 0.98 mm.

Eggs are most abundant between Cape Cod/Long Islandand Cape Hatteras (Figures 14 and 15); the heaviestconcentrations have been reported within 45 km of shore offNew Jersey and New York during 1965-1966 (Smith 1973),and from New York to Massachusetts during 1980-1986(Able et al. 1990). Able et al. (1990) discovered that thehighest frequency of occurrence and greatest abundances ofeggs in the northwest Atlantic occurs in October andNovember (Figure 15), although, due to limited sampling inDecember south of New England, December could be underrepresented. Festa (1974) also notes an October-Novemberspawning period off New Jersey. Keller et al. (1999) foundeggs (maximum density 19.5/100 in 3

) from February to Junein Narragansett Bay during a December 1989 to November1990 sampling period. In southern areas, eggs have beencollected as late as January-May (Figure 14; Smith 1973;Able et al. 1990).

The eggs have been collected mostly at depths of 30-70m in the fall, as far down as 110 m in the winter, and from10-30 m in the spring (Figure 16).

LARVAE

Planktonic larvae (2-13 mm) are often most abundant19-83 km from shore at depths of around 10-70 m, and arefound in the northern part of the Middle Atlantic Bight fromSeptember to February, and in the southern part fromNovember to May, with peak abundances occurring inNovember (Smith 1973; Able et al. 1990; Figures 17, 18,19). The smallest larvae (< 6 mm) were most abundant inthe Mid-Atlantic Bight from October-December, while thelargest larvae (> II mm) were abundant November-May

with peaks in November-December and March-May (Ableet al. 1990). Off eastern Long Island and Georges Bank, theearliest spawning and subsequent larval development occursas early as September (Able and Kaiser 1994). By October,the larvae are primarily found on the inner continental shelfbetween Chesapeake Bay and Georges Bank. DuringNovember and December they are evenly distributed overboth the inner and outer portions of the shelf. By Januaryand February the remaining larvae are primarily found onthe middle and outer portions of the shelf. By April, theremaining larvae are concentrated off North Carolina (Ableand Kaiser 1994).

From October to May larvae and postlarvae migrateinshore, entering coastal and estuarine nursery areas tocomplete transformation (Table 1; Merriman and Sclar1952; Olney 1983; Olney and Boehlert 1988; Able et al.1990; Szedlmayer et al. 1992). Larval to juvenilemetamorphosis, which involves the migration of the righteye across the top of the head, occurs over the approximaterange of 8-18 mm SL (Burke et al. 1991; Keefe and Able1993; Able and Kaiser 1994; Figure 20). They then leavethe water column and settle to the bottom where they beginto bury in the sediment and complete development to thejuvenile stage, although they may not exhibit completeburial behavior until mid-late metamorphosis when eyemigration is complete, often at sizes as large as 27 mm SL(Keefe and Able 1993, 1994). However, burying behaviorof metamorphic summer flounder is also significantlyaffected by substrate type, water temperature, time of day,tide, salinity, and presence and types of predators and prey(Keefe and Able 1994).

Keller et al. (1999) found larvae (maximum density1.4/100 in 3

) from September to December in NarragansettBay during a December 1989 to November 1990 samplingperiod. Able et al. (1990) and Keefe and Able (1993)discovered that some transforming larvae (10-16 mm)entered New Jersey estuaries primarily during October-December, with continued ingress through April; Allen et al.(1978) collected larvae (12-15 mm) in February and Aprilin Hereford Inlet near Cape May. Dovel (1981) recorded 9larvae in the lower Hudson River estuary, New York in1972. In North Carolina, the highest densities of larvae arefound in Oregon Inlet in April, while farther south inOcracoke Inlet, the highest densities occur in February(Hettler and Barker 1993). J.P. Monaghan, Jr. (NorthCarolina Dept. of Nat. Res. and Commer. Dev., MoreheadCity, NC, personal communication) mentions that for theyears 1986-1988, peak immigration periods of larvaethrough Beaufort Inlet and into North Carolina estuarieswere from late February through March. In the Cape FearRiver Estuary, North Carolina, it has been reported thatpostlarvae first enter the marshes in March and April and are9-16 mm SL during peak recruitment (Weinstein 1979;Weinstein et al. 1980b). Schwartz et al. (1979a, b) alsonotes that age 0 flounder appear in the Cape Fear Riverbetween March and May, depending on the year. Warlenand Burke (1990) found larvae (mean 13.1 mm SL) in the

Newport River estuary just inside Beaufort Inlet fromFebruary-April, 1986, with peak abundance in early March.Powell and Robbins (1998) reported larval summer flounderadjacent to live-bottom habitats (rock outcroppingscontaining rich invertebrate communities and many speciesof tropical and subtropical fishes) in Onslow Bay (near CapeLookout) in November (at stations of 17-22 m depth),February (28-30 m depth), and May (14-16 m and 17-22 mdepth). Burke et al. (1998) conducted night-time samplingfor transforming larvae and juveniles in Onslow Bay,Beaufort Inlet, and the Newport River estuary in February-March 1995. Although flounders were captured both inOnslow Bay and in the surf zone during the immigrationperiod, densities were low and all were transforming larvae(7-15 mm SL). After the immigration period, flounders wereabsent, as juveniles were not caught. Within the NewportRiver estuary, flounders were locally very abundant ascompared to within Onslow Bay and initial settlement wasconcentrated in the intertidal zone. During February mostwere transforming larvae, in March some were completelysettled juveniles (11-21 mm SL). In South Carolina, Burns(1974) captured summer flounder larvae (14.9-17.5 mm) inNew Bridge Creek, North Inlet estuary in February-March,while Bearden and Farmer (1972) recorded larvae andpostlarvae in Port Royal Sound estuary from January-March.During 1986-1988, Wenner et al. (I 990a) found that ingressof recently transformed larval and juvenile summer flounder(10-20 mm TL) into Charleston Harbor, South Carolinaestuarine marsh creeks began in January and continuedthrough April (Figure 21). Larvae and postlarvae were alsofound during this period in the Chainey Creek area (Wenneret al. 1986).

JUVENILES

As stated above, juveniles are distributed inshore (e.g.,Figure 22) and in many estuaries throughout the range of thespecies during spring, summer, and fall (Table 1; Deubler1958; Pearcy and Richards 1962; Poole 1966; Miller andJorgenson 1969; Powell and Schwartz 1977; Fogarty 1981;Rountree and Able 1992a, b, 1997; Able and Kaiser 1994;Walsh et al. 1999). During the colder months in the norththere is some movement to deeper waters offshore with theadults (Figure 3; Figure 23), although many juvenile summerflounder will remain inshore through the winter monthswhile some juveniles in southern waters may generallyoverwinter in bays and sounds (Smith and Daiber 1977;Wilk et al. 1977; Able and Kaiser 1994). In estuaries northof Chesapeake Bay, some juveniles remain in their estuarinehabitat for about 10 to 12 months before niigrating offshoretheir second fall and winter; in North Carolina sounds, theyoften remain for 18 to 20 months (Powell and Schwartz1977). The offshore juveniles return to the coast and baysin the spring and generally stay the entire summer.

Fogarty (1981) examined the distribution patterns ofprerecruit (< 30.5 cm) summer flounder caught during the

1968-1979 spring surveys and found a striking absence ofsmall fish in northern areas. Both spring and autumn bottomtrawl survey data indicated that the concentration of young-of-year summer flounder was south of 390 latitude. Theimportance of the Chesapeake Bight to this species isdemonstrated by the fact that almost all of the young-of-yearcaught during those spring surveys were from this area.

In Mid-Atlantic estuaries, first year summer floundercan grow rapidly and attain lengths of up to at least 30.0 cm(Poole 1961; Almeida et al. 1992; Szedlmayer et al. 1992).Young-of-the-year summer flounder in New Jersey marshcreeks have average growth rates of 1.3-1.9 mm/d, andincrease from about 16.0 cm TL at first appearance in lateJuly to around 26.0 cm by September (Rountree and Able1992b; Szedlmayer et al. 1992). First year fish fromPamlico Sound, North Carolina obtained mean lengths of16.7 cm for males and 17.1 cm for females (Powell 1982).In Charleston Harbor and other South Carolina estuariesfrom 1986-1988, Wenner et al. (1990a) found transforminglarvae were recruited into the estuarine creeks when 1-2 cmTL. Growth accelerated in May and June when they reachedmodal sizes of 8 and 14 cm TL, respectively. BySeptember, modal size was 16 cm TL and reached from 23-25 cm TL through October and November. Modal lengthsof yearlings ranged from 23-25 cm in January through Juneand generally reached 28 cm by October. In Georgia, labstudies by Reichert and van der Veer (1991) found thatjuveniles from Duplin River of 28-46 mm SL had amaximum growth rate of about 1.3-1.4 mm/d at laboratorytemperatures of 23.7-24.8°C.

Juvenile summer flounder make use of several differentestuarine habitats. Estuarine marsh creeks are important asnursery habitat, as has been shown in New Jersey (Rountreeand Able 1992b, 1997; Szedlmayer et al. 1992; Szedlmayerand Able 1993), Delaware (Malloy and Targett 1991),Virginia (Wyanski 1990), North Carolina (Burke et al.1991) and South Carolina (Bozeman and Dean 1980;McGovern and Wenner 1990; Wenner et al. 1990a, b).Other portions of the estuary that are used include seagrassbeds, mud flats and open bay areas (Lascara 1981; Wyanski,1990; Szedlmayer et al. 1992; Walsh et al. 1999).

Patterns of estuarine use by the juveniles can vary withlatitude. In New Jersey, nursery habitat includes estuariesand marsh creeks from Sandy Hook to Delaware Bay (Allenet al. 1978; Rountree and Able 1992a, b, 1997; Szedlmayeret al. 1992; Szedlmayer and Able 1993; B.L. Freeman, NewJersey Dept. of Environ. Prot., Trenton, NJ, personalcommunication). The juveniles often make extensive use ofcreek mouths (Szedlmayer et al. 1992; Szedlmayer and Able1993; Rountree and Able 1997). In the Hudson-Raritanestuary, New York and New Jersey, 1992-1997 surveysshow the juveniles to be present in small numbersthroughout the estuary in all seasons, with slightly highernumbers seen in the spring (Figure 24). In Great Bay,young-of-the-year stay for most of the summer, leaving asearly as August and continuing until November-December(Able et al. 1990; Rountree and Able 1992a; Szedlmayer

and Able 1992; Szedlmayer et al. 1992). As statedpreviously, Allen et al. (1978) collected both adult andjuvenile summer flounder (200-400 min) in Hereford Inletnear Cape May where they occurred in all of the majorwaterways, but were more abundant in the upper embaymentfrom May to July and in the lower embayment from Augustto October. Most were caught on the channel slopes.

Smith and Daiber (1977) report that in Delaware Bay,most summer flounder were collected May throughSeptember but a few juveniles have been caught in thedeeper parts of the Bay in every winter month. TheDelaware Bay Coastal Finfish Assessment Survey for 1996found juveniles throughout their April to October samplingperiod (Michels 1997).

In Maryland, J.F. Casey (Maryland Dept. of Nat. Res.,Ocean City, MD, personal communication) indicated thatalthough the coastal bays are excellent habitat for bothadults and juveniles (Schwartz 1961), in areas of significantpollution, a lack of proper food sources precludes thepresence of summer flounder. Other areas which lacksufficient water circulation also appear to have considerablyreduced populations. Shore-side development and resultantrunoff also appear to have reduced some local populations(Casey, personal communication). Since the 1970's,Maryland has been conducting trawl and seine surveysaround Ocean City inlet. Casey (personal communication)reported sharp declines in young-of-the-year flounder in thecoastal bay trawl samples. The majority of the summerflounder taken in this sampling were between 76 and 102mm, with larger fish basically absent. Summer flounderwere also sometimes found in Maryland's portion of theChesapeake Bay with the majority of these fish in the 200-300 mm range.

In Virginia, Musick (personal communication) statesthat the most important nursery areas for summer flounderappear to be in the lagoon system behind the barrier islandson the seaside of the Eastern Shore (Schwartz 1961), and theshoal water flat areas of higher salinity (> 18 ppt) in lowerChesapeake. Bay. Young-of-the-year enter these nurseryareas in early spring (March and April) and remain thereuntil fall when water temperatures drop. Then theseyearlings move into the deeper channel areas and down tothe lower Bay and coastal areas. In most winters these ageI + fish migrate out in the ocean but in warmer winters somemay remain in deep water in lower Chesapeake Bay(Musick, personal communication). However, the VirginiaInstitute of Marine Science juvenile finfish survey for 1995shows juvenile (as well as some adult) flounder occurringthroughout most of the main stem of Chesapeake Bay andthe major Virginia tributaries (Rappahannock, York, andJames Rivers) over most of the year (Geer and Austin 1996;Figure 25; see also Wagner and Austin 1999). Lowernumbers occurred from December-March (Figure 26).Wyanski (1990) found recruitment to occur from Novemberto April on both sides of Virginia's Eastern Shore and fromFebruary to April on the western side of Chesapeake Bay.Peak recruitment occurred in November-December on the

Eastern Shore, compared to March-April on the western sideof the Bay. Wyanski (1990) and Norcross and Wyanski(1988) also found that young-of-the-year occur in a varietyof habitats, including shallow, mud bottomed marsh creeks,shallow sand substrates (including seagrass beds), deep sandsubstrate, and deep fine-sand substrates.

Tagged summer flounder have been recaptured frominshore areas to the northeast of their release sites insubsequent summers, leading to the hypothesis that theirmajor nursery areas are the inshore waters of Virginia andNorth Carolina, and as they grow older and larger, theywould return inshore to areas farther north and east of thesenursery grounds (Poole 1966; Murawski 1970; Lux andNichy 1981). However, tagging studies by Desfosse (1995)indicate that it is not the older and larger fish, but rather thesmaller fish (length at tagging) which return to inshore areasnorth of Virginia. Summer flounder that were recapturednorth of their release site in subsequent years were smaller(length at tagging) than those recaptured at their releasesites, or to the south, in later years. Desfosse (1995)suggests that while Virginia waters do indeed form part ofthe nursery grounds for fish which move north in subsequentyears, they are primarily a nursery area for fish which willreturn to these same waters as they grow older and larger.

The estuarine waters of North Carolina, particularlythose west and northwest of Cape Hatteras (Monaghan1996) and in high salinity bays and tidal creeks of CoreSound (Noble and Monroe 1991), provide substantialhabitat and serve as significant nursery areas for juvenileMid-Atlantic Bight summer flounder. Powell and Schwartz(1977) found that juvenile summer flounder were mostabundant in the relatively high salinities of the eastern andcentral parts of Pamlico Sound, all of Croatan Sound (Figure13), and around inlets. Young-of-the-year disappeared fromthe catch during late summer, suggesting that the fish areleaving the estuaries at that time (Powell and Schwartz1977). Upon leaving the estuaries, the juveniles enter thenorth-south, inshore-offshore migration of Mid-AtlanticBight summer flounder (Monaghan 1996). Although NorthCarolina also provides habitat for summer flounder from theSouth Atlantic Bight, these fish do not exhibit the sameinshore-offshore and north-south migration patterns as doMid-Atlantic Bight fish (Monaghan 1996). Summerflounder > 30 cm are rarely found in the estuaries of NorthCarolina, although larger fish are found around inlets andalong coastal beaches. Powell and Schwartz (1977) alsonoted that juvenile summer flounder were most abundant inareas with a predominantly sandy or sand/shell substrate, orwhere there was a transition from fine sand to silt and clay.

Surveys by Hoffman (1991) in marsh creeks inCharleston Harbor, South Carolina showed that ricentlysettled summer flounder were abundant over a wide varietyof substrates including mud, sand, shell hash, and oysterbars.

HABITAT CHARACTERISTICS Dissolved Oxygen

No information is available.EGGS

Temperature

Smith (1973) found that eggs were most abundant in thewater column where bottom temperatures were between 12and 19"C; however, eggs were found in temperatures as coldas 9"C and as warm as 23°C. The Northeast FisheriesScience Center (NEFSC) Marine Resources Monitoring,Assessment, and Prediction (MARMAP) ichthyoplanktondata from 1978-1987 also shows that the eggs occur at watercolumn temperatures around I I -230 C with peak abundancesin the fall at temperatures of around 14-17"C (Figure 27). Atemperature increase of 20TC above an acclimationtemperature of about 15'C caused no mortality in earlyembryo stage eggs, but an increase of 16'C for 16 minutesor an increase of I 8'C for 2 minutes caused mortality in lateembryo stage eggs (Itzkowitz et al. 1983). The rate ofdevelopment is dependent on temperature, with developmentrate increasing as temperature increases. Embryos held at16"C developed slower than those at 21"C (Johns andHowell 1980). The incubation period from fertilization tohatching was estimated by Smith (1973) and Smith andFahay (1970) to vary with temperature as follows: about 142hours at 9'C; 72-75 hours at 18"C; and 56 hours at 23'C.Other incubation times under experimental conditions were48-72 hours at 16-21"C and 216 hours at 5TC (Johns andHowell 1980; Johns et al. 1981). In another study, summerflounder eggs required 72-96 hours to hatch while incubatedat temperatures ranging from 15-18"C (Smigielski 1975).Eggs from Narragansett Bay and Long Island Soundbroodstocks incubated at 12.5'C started hatching 85 hoursafter fertilization, while those incubated at 21 TC hatched 60hours after fertilization (Bisbal and Bengtson 1995c).

Watanabe et al. (1999) studied the combined effects oftemperature and salinity on eggs from captive summerflounder broodstock in the laboratory, and also showed thathigher temperatures and salinities accelerated the rate ofembryonic development through hatching. At 16TC and20'C, the hatching rate was moderate to high at allexperimental salinities (22, 27, and 33 ppt). At a highertemperature of 24 T, hatching rate was high at 33 ppt, butat lower salinities of 22 and 27 ppt, embryonic developmentand hatching was impaired, indicating a high-temperature-low-salinity inhibition.

Salinity

The studies of Watanabe et al. (1998, 1999; see alsoprevious section) suggest that whereas temperature producesmarked differences in developmental rates and medianhatching time of summer flounder embryos, the effects ofsalinity on median hatching time are relatively small.

Light

Watanabe et al. (1998) studied the effects of light oneggs from captive summer flounder broodstock in thelaboratory. Although the rate of embryonic developmentappeared to be faster at higher light intensities, hatching ratewas not influenced by light intensity within the range of 0-2,000 Ix.

Water Currents

No information is available.

Predation


LARVAE/JUVENILES

Temperature

Larvae have been found in temperatures ranging from0-23°C, but are most abundant between 9 and 18'C. NEFSCMARMAP ichthyoplankton data from 1977-1987 shows aseasonal shift in offshore larval occurrence with watercolumn temperatures (Figure 28): most larvae are caught attemperatures > 12'C in the fall, from 4-10'C in the winterand from 9-14'C in the spring. Sissenwine et al. (1979)found prerecruit summer flounder in the Mid-Atlantic Bightare often most abundant at temperatures in excess of 15'Cduring the spring, summer and fall, and usually at depths of40-60 m. Larval flounder have been collected inshoreearlier in years with mild winters than in years with severewinters (Cain and Dean 1976; Bozeman and Dean 1980). Inthe estuaries, transforming larvae (11-17 mm TL) have beencollected over a temperature range from -2.0-14'C in GreatBay/Little Egg Harbor in New Jersey (Szedlmayer et al.1992; Able and Kaiser 1994); from 2.1-17.6°C in the lowerChesapeake and Eastern Shore, Virginia (Wyanski 1990);from 2-22°C in North Carolina (Williams and Deubler1968b); and from 8.4-23.4"C in South Carolina (McGovernand Wenner 1990). Hettler et al. (1997) also reported anincrease in summer larval abundance with increasingtemperatures (7-18'C) in Beaufort Inlet, North Carolina;however,, they suggest that unknown factors are probablymore important in causing peaks in the abundances ofimmigrating larvae (see also Hettler and Hare 1998).

Johns and Howell (1980) and Johns et al. (1981)

performed experiments on yolk utilization and growth toyolk-sac absorption in summer flounder embryos and larvae.Notochord lengths at hatching were 2.83-3.16 mm SL, withyolk-sac absorption completed at about 3.6 mm SL. Forembryos and larvae reared at 21 TC, total yolk-sac absorptionwas complete by 120 h post-fertilization, at 16'C, completeabsorption did not occur until 168-182 h, while at I I1Cabsorption did not occur until 287 h post-fertilization; thesedevelopment times are similar to those reported byWatanabe et al. (1998) for larvae at 19TC. After hatching,total yolk-absorption at 21 C was complete in67 h, at 16TCit took 105 h, and at I 11C it took 137 h. Larvae reared incyclic temperature regimes exhibited development ratesintermediate to those at temperature extremes of the cycle.All larvae reared at 5TC and in the 5-1 ITC cycle regime diedprior to total yolk-sac absorption. Although incubationtemperature had a significant effect on the larval length athatching, there were no significant differences in thenotochord length or yolk utilization efficiency of the larvaeat the time of yolk-sac absorption. The similarity in growthand yolk utilization efficiency for larvae reared under thesetemperature regimes suggests that the physiologicalmechanisms involved are able to compensate fortemperature changes encountered in nature. Larvae are ableto acclimate to new temperatures in less than one day(Clements and Hoss 1977).

Watanabe et al. (1 999), using larvae hatched from eggsobtained from captive broodstock in the laboratory, alsoshowed that development of yolk-sac larvae through firstfeeding was accelerated by higher temperatures within therange of 16-24'C, consistent with what was previouslyreported by Johns and Howell (1980) and Johns et al.(1981). In all three studies the rate of yolk disappearance(yolk utilization efficiency) was faster at highertemperatures. Watanabe et al. (1999) showed that theaverage time from the first-feeding to when 97% of the yolk-sac was absorbed in unfed larvae ranged from 2.4 to 4.3times longer at 16TC (18.3 h) than at 20'C (4.3 h) or 24'C(7.7 h). Thus, larvae in 16'C waters may have considerablymore time to initiate exogenous feeding before yolk reservesare exhausted [see also the discussion of the Bisbal andBengtson's (1995c) study, below].

However, contrary to the Johns and Howell (1980) andJohns et al. (1981) studies, lower temperatures in theWatanabe et al. (1999) study produced larger larvae at thefirst-feeding and 97% yolk-sac absorption stages. Watanabeet al. (1999) state that these dissimilar results areattributable to the modifying influence of salinity, whichdiffered between these studies (see the Salinity section,below). In their study, Watanabe et al. (1999) noted a high-temperature-low-salinity inhibition on growth and yolkutilization efficiency, but at a salinity of 33 ppt, there wereno temperature-related differences in yolk utilizationefficiency. Watanabe et al. (1999) suggest this may beconsistent with what was observed in the Johns and Howell(1980) and Johns et al. (1981) studies, which used seawaterof an unspecified salinity.

Further interactions of temperature and salinity in theWatanabe et al. (1999) study will be discussed in theSalinity section, below.

Bisbal and Bengtson (1995c) show the interdependenceof temperature and food availability (i.e., delay of initialfeeding) and their effects on survival and growth of summerflounder larvae hatched from Narragansett Bay and LongIsland Sound broodstock. Their laboratory observationsoccurred from the time of hatching throughout the period offeeding on rotifers. The larvae withstood starvation forlonger times at lower temperatures. They possessedsufficient reserves to survive starvation for 11 to 12 dayswhen temperatures were maintained close to theexperimentally determined lower tolerance limit (12.5°C;Johns et al. 1981). At temperatures close to the highestthermal limit reported to occur in their environment (21 0C;Smith 1973), larvae only survived for 6 to 7 days. At eithertemperature, best survival occurred when the larvae beganto feed at the time of mouth opening, thus survival is alsosignificantly affected by the time at which they first haveaccess to exogenous food. At 12.50 C, every treatment groupwas represented by a low number of survivors which did notgrow significantly from the initial figures at mouth opening.Growth of the larvae at 21 C was inversely proportional tothe duration of early starvation; the size distribution of thesurvivors of the 21'C experiment showed an increase inmean size and weight when the initial feeding delay wasshorter.

The prevailing temperature conditions influence theduration of metamorphosis of pelagic larvae, with increasingtemperatures resulting in a shorter metamorphic period. Forexample, Keefe and Able (1993) found the time tocompletion of metamorphosis in wild-caught New Jerseyflounder maintained in the laboratory was clearlytemperature dependent. While laboratory-reared summerflounder averaged 24.5 days (range 20-32 days) to completemetamorphosis (stage F- to stage I) at ambient springtemperatures of around 16.60C, wild-caught flounder held inheated water (daily average 14.5'C) advancedmetamorphosis over controls kept at ambient wintertemperatures (daily average 6.6°C). Total time required tocomplete metamorphosis in the heated water averaged 46.5days (range 31-62 days); ambient winter temperaturetreatments resulted in delayed metamorphosis such thatpartial metamorphosis (stage H- to stage I) required as muchas 92.9 days (range 67-99 days). Burke (1991) found thatsettling behavior of fish raised at I 8-200C occurred 28 daysafter hatching, although some took as long as 70 days.

Keefe and Able (1993) also found that mortality duringmetamorphosis in the laboratory ranged from 17-83%among treatment groups, and was significantly greater inflounder maintained at approximately 4'C relative to thosemaintained at ambient New Jersey estuarine temperatures ofaround 10.1 0C. They found no apparent effect of starvationon either mortality or time to completion of metamorphosisat cool water temperatures (< 10°C). Szedlmayer et al.(1992) examined the temperature-induced mortality of

young-of-the-year, early postmetamorphic (11-15 mm TL)summer flounder collected in New Jersey estuaries fromNovember to May over a temperature range of 0-13TC.Survival of metamorphosing larvae in the laboratory*decreased drastically relative to controls when temperaturesdropped below 2'C. In trial 1, temperatures droppedsteadily from 15-I° C over a 14-day period. Relatively littlemortality (2%) occurred up to day 12. However, on days 13and 14, temperatures dropped below 2'C causing 58%mortality. Temperatures then increased and fluctuatedaround 5oC but did not drop below 3"C, and during thisperiod, mortality was lower (14%), for a total ambienttemperature mortality of 74%. Only 3% total mortalityoccurred due to rearing environment in the control group,heated to 15TC. During trial 2, in which controls wereabsent and ambient temperatures did not drop below 2°C,overall mortalities were lower (31% total) and theseoccurred sporadically.

Malloy and Targett (1991) conducted laboratoryexperiments on juvenile summer flounder (41-80 mm TL)collected from Delaware to determine low temperaturetolerance (2-30 C) and to measure feeding rate, assimilationefficiency, growth rate and growth efficiency at varioustemperatures. Above 3'C, all the juveniles survived.Mortality was 42% after 16 days at 2-3'C, and was highestin fish < 50 mm TL (1 g). Mean specific growth rates werenot significantly different between 2 and 10'C, and theserates were not significantly different from zero. Additionalmortality probably resulted from low growth rates caused bysub-optimal temperatures (< 10"C). Malloy and Targett(1994a) also demonstrate that mortality of juveniles dependsmore on the rate of temperature decline than on the finalexposure temperature: increased rate of temperature declineleads to decreased survival (lower LT5 0 's). Their studyshowed that juveniles from Delaware had greater tolerancesfor low temperatures (1-4TC) than juveniles from NorthCarolina.'

Malloy and Targett (1994a) showed that undermaximum-feeding conditions, juvenile summer flounder(18-80 mm TL) from both Delaware and North Carolina donot exhibit positive growth rates at temperatures < 7-9°C.[They consider this a more precise estimate of maintenancetemperature than that reported in their earlier study (Malloyand Targett 1991).] Similarly, Peters and Angelovic (1971)in their laboratory studies of North Carolina juvenilesreported predicted growth rates of close to zero at 10C.Growth rates of juvenile flounder at temperatures above10C are similar in studies on Delaware fish by Malloy andTargett (1991) and on North Carolina fish by Peters andAngelovic (1971). Malloy and Targett (1991) showed thatmean growth rate increased to 2.4% per day at 14TC and3.8% per day at 18'C and Peters and Angelovic (1971)demonstrated that specific growth rates of North Carolinajuveniles were 5% and 10% per day, at 15 and 20'C,respectively. Both studies showed that feeding ratesincreased with temperature, ranging from 1.04% bodyweight per day at 2TC to 23-24% body weight per day at

18TC. Peters and Angelovic (1971) reported an increase infeeding and growth efficiency rates with increasingtemperatures to an optimum; beyond that optimumincreasing temperatures are detrimental. The optimaltemperature in their experiments was 21'C. Meanassimilation efficiency' (60.1%) was not affected bytemperature in the Malloy and Targett (1991) study. Meangrowth efficiency (K1 ) for Delaware juveniles wassignificantly lower at 6'C (-23.1%) than at 14 and 18°C(18.4 and 22.1% respectively) and was highly variable.Malloy and Targett (1994a, b) conclude that North Carolinajuveniles had higher maximum growth rates and grossgrowth efficiencies than Delaware juveniles at temperaturesbetween 6 and 18TC. Growth efficiency accounted for mostof these differences in growth rates, because there were nodifferences in feeding rate or assimilation efficiency. Newlysettled juveniles likely remain at settlement sizes for up to 6months until temperatures are conducive for positive growth(Able et al. 1990; Malloy and Targett 1991, 1994b).

Malloy and Targett (1994a) also reported that juvenilesfrom North Carolina and Delaware can survive at least 14 dwithout food at the 10-16'C temperatures typically foundafter settlement. However, growth rates are dependent onfeeding rate at all temperatures they examined. Growth ratesunder starvation conditions and maintenance rations do notchange between 10-16'C; however, scope for growthincreases with temperature. Scope for growth of the NorthCarolina juveniles was higher than that of the Delawarejuveniles between 10-16TC. In another study, Malloy andTargett (1 994b) showed that juveniles (18-80 mm TL) fromboth Delaware and a North Carolina sandy marsh wereseverely growth limited (< 20% of maximum growth) inMay and June when temperatures were 13-20TC. Malloyand Targett (1 994a, b) conclude that prey availability is veryimportant to the growth and condition of early juvenilesduring the months immediately following settlement, andchanges in prey abundance may explain the patterns ingrowth limitation.

Mortality resulting from acute exposure to lowtemperatures in Mid-Atlantic Bight estuaries probablyoccurs during a 2 to 4 week period each winter. Szedlmayeret al. (1992) hypothesized that year class strength may beaffected by winter temperature in New Jersey estuaries, ashas been suggested for juveniles by Malloy and Targett(1991) for the Mid-Atlantic Bight as a whole. Recruitmentsuccess may be lower in years with late winter cold periods(i.e., March vs. December) due to increased numbers of fishinshore at that time of the year being exposed to lethal lowtemperatures (Malloy and Targett 1991). Thus, the timingof ingress is critical. However, because Malloy and Targett(1991) found that there was 100% survival at temperaturesabove 3'C, juveniles are probably able to survive mostwinter water temperatures encountered throughout Mid-Atlantic Bight estuaries. However, Malloy and Targett(1994a) state that the magnitude of the variability in lowtemperatures may also be more important to prerecruitmortality than the magnitude of the temperature itself. The

low feeding rates observed at low temperatures in thelaboratory and the apparent lack of a starvation effect onlow-temperature tolerance suggest that food limitationduring winter is less important than the magnitude andvariability of temperature minima. They conclude thatalthough low temperatures may contribute to prerecruitmortality south of Cape Hatteras, they are probably moreimportant in more northern nurseries because they persistlonger there. In New Jersey, the most probable factorsaffecting survival of metamorphic summer flounder are theprevailing environmental conditions, especially the timingof ingress relative to estuarine water temperatures andpredation (Szedlmayer et al. 1992; Keefe and Able 1993;Witting and Able 1993).

Tracking studies by Szedlmayer and Able (1993) inSchooner Creek, near Great Bay and Little Egg Inlet, NewJersey, suggest that tidal movements of juveniles (210-254mm TL) may be in response to a preferred range ofenvironmental parameters. Although they were collected ina wide range of habitats during their first year (Szedlmayeret al. 1992), during the August to September study period,they were found within a narrow range of water temperature(mean 23.5"C) and also dissolved oxygen. Small changes inthese parameters may force the fish to move.

Several studies indicate that juvenile summer flounderin Chesapeake Bay may succumb to infections of thehemoflagellate Trypanoplasma bullocki at low temperatures(Burreson and Zwerneir 1982, 1984; Sypek and Burreson1983). Effective immune response to the parasite was notnoted in natural infections below 10C (Sypek and Burreson1983). Therefore, because T. bullocki causes mortality ofjuvenile summer flounder during winter, suggesting that thismortality is temperature dependent, and since no fish withsymptoms of the disease have been observed south of CapeHatteras, Burreson and Zwerner (1984) hypothesize that thepresence of the symptoms of this disease in juvenile summerflounder can be used as a measure of mortality north of CapeHatteras. In addition, increased antibody production in earlyspring eliminates the infection in the flounder and therecovered fish are immune for at least one year, even ifchallenged at temperatures as low as 9'C (Burreson andFrizzell 1986).

NEFSC groundfish data shows a seasonal shift inoffshore juvenile summer flounder occurrence with bottomtemperatures (Figure 29): most juveniles are caught over arange of temperatures from. 10-27°C in the fall, from 3-13'Cin the winter, from 3-17'C in the spring, and from 10-27TCin the summer. Massachusetts inshore trawl survey data alsoshows a seasonal shift in juvenile occurrence with bottomtemperature (Figure 30). In the spring, most juveniles occurat a range of temperatures from 9-14'C, while in the fall theyoccur at temperatures from 15-2 1"C.

Salinity

Watanabe et al. (1998) studied the effects of salinityand light intensity on yolk-sac larvae hatched from captivesummer flounder broodstock in the laboratory. Significanteffects of both salinity and light intensity on larval size wereevident at hatching: larvae hatched under 500 Ix andsalinities of approximately 35 ppt showed maximum values,a trend observed at the first feeding stage. However, in alater study by Watanabe et al. (1999), salinity did notinfluence development and growth rates of yolk sac larvaethrough the first feeding stage. Watanabe et al. (1998)suggest that the differences among the two studies may beattributed to the lower salinity range (22-33 ppt) used in thislater study.

Also in the Watanabe et al. (1999) study, a hightemperature of 240C, although not greatly influencing larvalsurvival at 33 ppt, markedly impaired survival at the 97%yolk-sac absorption stage when salinities were at 22 and 27ppt, indicating high-temperature-low-salinity inhibition.Conversely, a low temperature of 16'C enhanced larvalsurvival at these reduced salinities, indicating a low-temperature-low salinity synergistic effect. Watanabe et al.(1999) therefore hypothesize that moderate to high survivalunder all salinities at 16'C reflects an adaptability of theyolk sac larvae to inshore movement during the pelagiclarval phase, whereas simultaneous exposure to highertemperatures and reduced salinities may increase mortalityand affect year-class strength.

Transforming larvae and juveniles are most oftencaptured in the higher salinity portions of estuaries. In NewJersey, Festa (1974) captured larval summer flounder insalinities of 26.6-35.6 ppt, while in two marsh creeks, larvaeoccurred at salinities ranging from 20-33 ppt (Able andKaiser 1994). In the lower Chesapeake Bay, Virginia,young-of-the-year were common in creeks with salinities >15 ppt and were most abundant at the highest salinities, butwere absent in a small tributary of the Poropotank Riverwith salinities 3-11 ppt (Able and Kaiser 1994). In NorthCarolina, Williams and Deubler (1968a) found postlarvalsummer flounder in waters ranging from 0.02-35 ppt, withoptimal conditions at 18 ppt. In addition, postlarval summerflounder (10-18 mm SL) were captured most frequently atsalinities exceeding 7.4 ppt in the Cape Fear River Estuary,North Carolina (Weinstein et al. 1980b). However, Turnerand Johnson (1973) reported that summer flounder of allages occurred in the Newport River, North Carolina, atsalinities of 3-33 ppt. Data from 1987-1991 trawl surveysfrom Pamlico Sound show that almost all individuals werecollected in the sound while few were found in the adjacentsubestuaries with lower salinities such as the Pamlico andNeuse Rivers (Able and Kaiser 1994). M. Street (NorthCarolina Dept. of Nat. Res. and Commer. Dev., MoreheadCity, NC, personal communication) mentioned that summerflounder distribution in Pamlico Sound varied in response tosalinity changes. In dry years the area of higher salinity

greatly expands in Pamlico Sound, and nursery areassimilarly expand. In South Carolina, larvae have beencollected at salinities from 0-24.7 ppt (McGovern andWenner 1990). Recently settled individuals (< 50 cm TL)in the Charleston Harbor estuary occur at both very low andvery high salinities from February to March (Figure 31).However by May, individuals 20-100 mm TL are found athigher salinities of > 10 ppt. This suggests that as theflounder disperse in this estuary, they may move up intonearly fresh water, but as they grow they concentrate in thehigher salinities of the lower estuary (Wenner et al. 1990a;Hoffman 1991; Able and Kaiser 1994).

In an estuarine complex in Georgia, Dahlberg (1972)noted that adult and juvenile summer flounder were mostabundant in the higher salinity zones.

Malloy and Targett (1991) found that salinities of 10-30ppt had no significant effect on feeding, growth, or survivalof juvenile summer flounder (41-80 mm TL) in Delaware.However, there was a slight interaction of temperature andsalinity on growth rate, suggesting that fish have highergrowth rates at high salinities and at high temperatures. Thisagrees with other laboratory studies which show that larvaland juvenile growth rate and growth efficiency are greatestat salinities > 10 ppt (Deubler and White 1962; Peters andAngelovic 1971; Watanabe et al.' 1998, 1999), althoughMalloy and Targett (1991) suggest that there appears to beno significant physiological advantage or greater capacityfor growth in waters of higher salinities, except at hightemperatures. In other laboratory experiments, however,summer flounder grew best at higher salinities and moremoderate temperatures, typical of habitats close to themouths of estuaries (Peters 197 I). This could explain whyPowell and Schwartz (1977) captured juveniles in the centralportions. and around inlets of North Carolina estuaries atintermediate to high salinities of 12-35 ppt. Burke (1991)and Burke et al. (1991) also found newly settled summerflounder concentrated on tidal flats in the middle reaches ofa North Carolina estuary. In the spring, older juvenilesmoved to high salinity salt marsh habitats. Young-of-the-year in spring were also significantly correlated with salinity(around 22-23 ppt) in eelgrass (Zostera marina) beds in theshallow water (1.2 m), high salinity area near Hog Island inPamlico Sound (Ross and Epperly 1985; it is unclear if thisapplies to the larger juveniles and adults caught in the studywith sizes up to 320 mm). Walsh et al. (1999), sampling inthe Newport River and Back Sound estuaries adjacent toBeaufort Inlet from April-October 1994, also found thatduring the spring, larger juveniles (e.g.; 57, 60, 78 mm meanSL) occurred in the high salinities of the lower estuary onsand flats and in channels and along marsh edges.

But Burke (199 1) and Burke et al. (1991) make it clearthat the summer flounder's distribution is due to substratepreference and is not affected by salinity. Malloy andTargett (1991) also suggest that reported distributions ofjuvenile summer flounder at salinities > 12 ppt are probablythe result of substrate and prey availability. In addition, thedata of Walsh et al. (1999) from the Newport River and

Back Sound estuaries* suggest that temperature, salinity,turbidity, and substrate type are related to juvenile summerflounder distribution and area of settlement, though theywere unable to separate the independent effect of thesevariables.

Dissolved Oxygen

Klein-MacPhee (1979) measured oxygen consumptionrhythms in juvenile summer flounder over a 24 hour periodin a flow-through metabolic chamber. The flounder showeda standard metabolic rate cycle, as manifested by oxygenconsumption, with maximum consumption occurringbetween the hours of 2300 and 0100, and a minimumbetween 1130 and 1300. Oxygen consumption variedinversely with the size of the fish. Mean oxygenconsumption was 33.5 mg/kg body weight per hour for 120g fish; 31.1 mg/kg body weight per hour for 165 g fish; and22.9 mg/kg per hour for 250 g fish. Comparisons ofmetabolic rate cycles with activity cycles showed that thepattern was the same (high activity, high oxygenconsumption in -the dark) but the peaks of the two cycles didnot always coincide, and there was less day to day variationin the oxygen consumption cycle.

As reported previously under the temperature section,tracking studies by Szedlmayer and Able (1993) in SchoonerCreek, near Great Bay and Little Egg Inlet, New Jerseysuggest that tidal movements of juveniles (210-254 mm TL)may be in response to a preferred range of environmentalparameters. They were found within a narrow range ofwater temperature and dissolved oxygen (mean 6.4 ppm),and small changes in these parameters may force the fish tomove.

Postlarvae of the closely related southern flounder(Paralichthys lethostigma) responded negatively to waterwith dissolved oxygen concentrations < 3.7 ml/l (or 5.3mg/1) (Deubler and Posner 1963). The southern floundersalso showed no difference in sensitivity to oxygen depletionwhen subjected to temperatures of 6.1, 14.4 and 25.3TC.Growth rates of young-of-the-year winter flounder(Pseudopleuronectes americanus) were significantlyreduced for fish exposed to low (2.3 ppm) and diurnallyfluctuating (2.5-6.5 ppm; avg. 5.1 ppm) levels of dissolvedoxygen (Bejda et al. 1992).

Light

As stated previously, Watanabe et al. (1998) studied theeffects of light intensity and salinity on yolk-sac larvaehatched from captive summer flounder broodstock in thelaboratory. Significant effects of both salinity and lightintensity on larval size were evident at hatching: larvaehatched under 500 Ix and salinities of approximately 35 pptshowed maximum values, a trend observed at the first

feeding stage. Shorter notochord lengths of larvae grownunder a light intensity of 2,000 lx compared with 0-1,000 lxis presumably related to higher light-induced activity andenergy metabolism. 500 Ix appears to be the optimalintensity for culture of eggs and yolk-sac larvae.

Hettler et al. (1997) found that larvae inside BeaufortInlet, North Carolina were more abundant in catches madelater in the night, suggesting that they disperse into the watercolumn from the edges and bottom. Night-time sampling byRountree and Able (1997) at the mouths of marsh creeks inLittle Egg Harbor estuary, New Jersey, suggests that young-of-the-year (range 138-390 mm SL) summer flounder makeextensive use of these shallow habitats during night-timehours.

White and Stickney (1973) found that late larval andearly postlarval summer flounder reared in the laboratoryfeed well with a surface light intensity of 300-500 footcandles (1 foot candle = 10.76 meter candles). Otherlaboratory studies by Keefe and Able (1994) in New Jerseysuggest that metamorphic flounder exhibit a diel pattern inburying behavior with a higher incidence of buryingoccurring during the day, with swimming in the watercolumn at night. Klein-MacPhee (1979) showed that, under12 h light/12 h dark photoperiods, maximum activity by

juveniles occurred in the dark and had a bimodaldistribution. Peaks occurred at 1900 and 0400 h. Underconstant dark regimes, peak activity occurred at 2000 and0100 with a minor peak at 1200. The free running periodwas 26 hours. In natural light, major activity occurred at0300 with minor peaks at'1200 and 1800 h. In constantlight, activity was reduced and found to be acyclic. Activitypatterns of laboratory juveniles were different from wildadults, the latter being light active. Laboratory studies byLascara (1981) on juveniles and adults from lowerChesapeake Bay showed that peak feeding activity (search-pursuits/unit time) generally occurred .during daylight hoursbetween 0800 and 1200.

Grover (1998) studied the incidence of feeding ofoceanic larval summer flounder collected north and east ofHudson Canyon. The incidence of feeding was defined asthe percentage of frequency of larvae with prey in their guts,in relation to the total number of specimens examined in atime block. Pelagic larvae began feeding near sunrise; thepresence of prey in the guts reached its lowest point at 0400-0599, then dramatically increased at 0600-0759. At 0800-0959, the incidence of feeding was 100%, and throughoutdaylight remained high until 2000. Full guts were notobserved until 1200-1359. Maximum gut fullness was at1200-1559 and 2000-2159. The only time block in whichall larvae contained prey in their guts was at 0800-0959.These observations confirm the visual nature of oceaniclarval feeding. The incidence of feeding in estuarine larvaewas significantly lower than oceanic larvae at 1800-1959and 2000-2159.

Surveys in the lower Chesapeake Bay, Virginia (Orthand Heck 1980; see also Lascara 1981) and near BeaufortInlet, North Carolina (Adams 1976a) show that during

daylight hours, juveniles tend to occupy areas in theestuaries that have submerged aquatic vegetation.

Water Currents

Smith (1973) found that larvae did not drift far-fromspawning areas, and were taken near the eggs. Williams andDeubler (1968a) stated that larvae shorter than 7 mm SLdepend on currents for dispersal; however, there are no datathat describe relationships between recruitment to nurseryareas and wind-driven (Ekman) transport or prevailingdirections of water flow. Greater densities of young fishwere found in or near inlets, and greater numbers werecaptured during periods of the full moon (Williams andDeubler 1968a). Young-of-the-year summer flounder havebeen found in high concentrations around the mouths of tidalcreeks (Szedlmayer et al. 1992; Szedlmayer and Able 1993;Rountree and Able 1997). This could serve to maximizeenergy efficiency, as the creek mouths are often areas ofreduced current speed.

Laboratory experiments by Keefe and Able (1994) inNew Jersey indicated an increase in burying behavior byearly metamorphic summer flounder on a flood tide.Although this may represent a mechanism that allows theflounder to remain in favorable habitats, field studies byBurke et al. (1998) showed that during flood' tides inBeaufort Inlet, North Carolina, the highest densities oftransforming larvae occurred at mid-depths within the watercolumn, while during ebb tide, the highest densities were atthe bottom. Their position in the water column wasdependent on tidal stage, and there was a shift in theirdistribution and abundance which was associated with theshift in tidal stage. However, the increase in the numbers offlounders in the water column occurred around slack tide,and preceded the rise in salinity which followed the onset offlood tide (Burke et al. 1998).

Dispersal in areas having strong tidal currents may beaccomplished by diel vertical migrations that result in tidaltransport (Weinstein et al. 1980a; Burke 1991; Burke et al.1991; Burke et al. 1998). The shift in vertical distributionwith tidal stage observed by Burke et al. (1998) in BeaufortInlet indicates that flounders in Onslow Bay enter theestuary by tidal stream transport. In the laboratory, Burke etal. (1998) discovered that wild-caught G-H stage larvae hada regular pattern of activity correlated with the tidal cycle,and peak activity was associated with the time of ebb tide.Interestingly, laboratory-reared flounder had no clear patternof activity. The observed tidal rhythm of activity of the wild-caught flounder, coupled with field observations that theyappear to make the vertical shift into the water columnduring slack tide (see previous paragraph) when currentvelocities are low, suggests that there is a behavioralcomponent to their tidal stream transport (Burke et. al.1998). The high activity during ebb tide seen in thelaboratory suggests that the most active behavioralcomponent of tidal stream transport involves avoidance of

advection by the ebbing tide rather than movement into thewater column and transport by the flood tide (Burke et al.1998). Burke et al. (1998) also hypothesize that a change inbehavior necessary for development of a tidal rhythm occursduring the eye migration phase of metamorphosis. The lackof a tidal activity pattern seen in laboratory-reared floundersuggests that development of a tidal rhythm is dependent onexposure to physical variables that are correlated with thetide.

Tidal transport of young-of-year summer flounder hasalso been shown to occur in a New Jersey marsh creek(Szedlmayer and Able 1993). Fish moved up the creek onflood tides and down the creek with ebb tides. Rountree andAble (1992b) and Szedlmayer and Able (1993) hypothesizethat tidal movements of summer flounder in marsh creeksare the result of both foraging behavior and behavioralhomeostasis (e.g., behavioral thermoregulation). Stomachfullness of fish captured leaving the creeks on ebb tides wassignificantly greater than that of fish captured entering thecreeks on flood tides, suggesting that summer flounderundergo tidal movements to take advantage of highconcentrations of prey available in the creeks. Although theflounder were found in a wide range of temperatures,salinities and dissolved oxygen concentrations, theygenerally stayed within narrow limits of these parameters.Thus, movements may be related to the avoidance ofenvironmental extremes.

Substrate/Shelter

Powell and Schwartz (1977) state that benthic substrateappears to influence juvenile summer flounder and southernflounder distributions in Pamlico Sound and adjacentestuaries, North Carolina. Summer flounder were dominantin sandy substrates or where there was a transition from finesand to silt and clay, while southern flounder were dominantin muddy substrates. Turner and Johnson,(1973) also notejuvenile summer flounder occur more frequently over sandysubstrates than mud or silt bottoms in Pamlico Sound.Burke (1991) and Burke et al. (1991) demonstrated in theirNorth Carolina study that it is salinity which affects thedistribution of southern flounder while the most importantfactor affecting the distribution of summer flounder issubstrate type. Their data indicated that the highestprobability of encountering juvenile summer flounderoccurred on mixed to sandy substrates.

Walsh et al. (1999), who collected juveniles onlyduring the spring and summer in estuaries adjacent toBeaufort Inlet from April-October 1994, also noted the samespecies-specific preferences in the type of marsh edgehabitat occupied. Juvenile southern flounder were moreabundant in the low salinity upper estuary on muddiersubstrates, while summer flounder juveniles were moreabundant at higher salinities and on sandier substrates.However, regarding juvenile summer flounder abundancesalone, they found no significant differences across the

various habitat types within the estuaries. Indeed, duringboth seasons, but particularly in the spring, higherabundances of recently recruited juveniles were found alongmarsh edges in mud substrate. Lower numbers were foundon sand flats and channels in the lower estuary. There was,however, evidence of size-specific habitat segregationduring the spring, with the larger juveniles (e.g.; 57, 60, 78mm mean SL) occurring in those sand flats and channels inthe lower estuary. As stated above, although the data ofWalsh'et al. (1999) suggest substrate type, along withtemperature, salinity, and turbidity are related to juveniledistribution and area of settlement, they were unable toseparate the independent effect of these variables.

Juveniles make extensive use of marsh creeks (Wyanski1990; .Burke et al. 1991; Malloy and Targett 1991; Rountreeand Able 1992b, 1997; Szedlmayer et al. 1992; Szedlmayerand Able 1993) as well as other estuarine habitats. Forexample, as stated previously, surveys by Hoffman (1991)in marsh creeks in Charleston Harbor, South Carolina alsoshowed that recently settled summer flounder were abundantover a wide variety of substrates including mud, sand, shellhash, and oyster bars. In Virginia, Wyanski (1990) andNorcross -and Wyanski (1988) found. newly recruitedjuvenile summer flounder in shallow, mud bottomed marshcreek habitat until they were 60-80 mm TL in late spring, atwhich time they were on shallow sand substrates (includingseagrass beds), deep sand substrate, and deep fine-sandsubstrates. Although Keefe and Able (1994) found thatmetamorphic and juvenile summer flounder collected fromGreat Bay-Little Egg Harbor estuary in southern New Jerseyshowed a preference for sandy substrates in the laboratory,studies by Szedlmayer et al. (1992) and Rountree and Able(1992a, 1997) show that in southern New Jersey they alsooccur abundantly in marsh creeks with soft mud bottoms andshell hash.

Substrate preferences of metamorphic and juvenilesummer flounder, as well as burying behavior, may becorrelated to the presence and types of predators and prey(Keefe and Able 1994). For example, in North Carolinaestuaries, Burke (1991) suggests the preferred habitat ofsummer flounder appears to be in the mid-estuary, whichalso appears to correspond to high densities of theirprincipal prey. This in spite of the fact that Burke (1991)also demonstrated that metamorphosing larvae raised in thelab exhibit substrate preferences that correspond to thehabitat of older flounders in the wild, preferring sandwhether benthic prey species were present or excluded fromtest substrates. Timmons (1995) also reported a preferencefor sand by juvenile (7.6-24.9 cm TL) summer flounderfrom the south shores of Rehobeth and Indian River Bays,Delaware, but in addition the flounder were captured nearlarge aggregations of the macroalgae Agardhiella teneraonly when large numbers of their principal prey, the grassshrimp Palaemonetes vulgaris, were -present. Timmons(1995) suggests that the summer flounder are attracted to thealgae because of the presence of the shrimp, but remain nearthe sand to avoid predation ("edge effect"). Indeed, in her

laboratory experiments, the juvenile summer flounder didnot show a preference for the macroalgae, and in cagingexperiments, blue crabs were least able to prey on theflounder in cages with sand bottoms only, but had anadvantage in capturing the flounder in cages containingmacroalgae. Similar results have been reported inlaboratory experiments by Lascara (1981) on largerjuveniles and adults from lower Chesapeake Bay. Flounderappeared to utilize submerged aquatic vegetation (eelgrass)as a "blind", they lie-in-wait along the vegetative perimeter,effectively capturing prey (in this case, juvenile spot,Leiostomus xanthurus) which moved from within the grass.In the absence of the eelgrass, the spot visually detected andavoided the flounder; the flounder therefore consumed fewerspot on average in the non-vegetated treatment than in thevegetated treatments. Therefore, Lascara (1981) concludesthat the ambush tactics of summer flounder are especiallyeffective when the flounder are in patchy habitats where theyremain in the bare substrate (sand) between eelgrass patches.Lascara (1981) also noted that if flounder remained withindensely vegetated areas, they would probably beconspicuous to prey. As the flounder moved through thevegetation in his laboratory experiments, the grass bladeswere matted down and essentially "traced out" their bodyshape. The flounder might also be conspicuous to potentialpredators as well,' again suggesting the "edge effect"hypothesis of Timmons (1995). Thus, flounder remain nearthe sand to both avoid predation and conceal themselvesfrom prey.

Other studies have shown that summer flounder usevegetated habitats. Adams (I 976a) reported the occurrenceof juvenile summer flounder in eelgrass meadows nearBeaufort, North Carolina during the summer; YOY juvenilesin spring also appeared to favor the eelgrass beds in theshallow water (1.2 m), high salinity (means 22-28 ppt) areanear Hog Island in Pamlico Sound (Ross and Epperly 1985).Paralichthys spp. in the eelgrass communities near Beaufort,North Carolina collectively accounted.for about 1% of theannual production and respiration of the fish assemblage(Thayer and Adams 1975; Adams 1976b). Hettler (1989)also reported juveniles in North Carolina salt marshcordgrass habitat during flood tides. Orth and Heck (1980)and Heck and Thoman (1984) indicated that summerflounder used similar shallow vegetated areas duringdaylight in Chesapeake Bay; Lascara (1981) reports thatjuvenile and adult flounder entered and fed in these sameareas. In a Virginia tidal marsh creek prior to late summer,juveniles were randomly distributed, but in late summer andearly fall, they were more abundant in the adjacent seagrassbeds (Weinstein and Brooks 1983). These data indicate thatgrass bed habitats are important to summer flounder, andany loss of these areas along the Atlantic seaboard mayaffect flounder stocks (Rogers and Van Den Avyle 1983).In the inland bays of Delaware, Timmons (1995) suggeststhat macroalgal systems appear to act as ecologicalsurrogates to seagrass beds and seagrass/macroalgal systemsas described by various authors. As with seagrass systems'

that attract juveniles when the submerged aquatic vegetation(SAV) increases from June to September, so does themacroalgae attract summer flounder, because, as statedpreviously, the macroalgae attracts their prey. This may alsobe true for Great Bay and Little Egg Harbor in southernNew Jersey. Szedlmayer and Able (1996) report thatjuvenile and adult summer flounder (140-416 mmn SL) wereassociated with the station considered to be a sea lettuce(Ulva lactuca) macroalgae habitat.

Conversely, also in Great Bay-Little Egg Harbor, Keefeand Able (1992) determined habitat quality as measured byrelative growth of juvenile summer flounder (17-41 mm SL).Growth did not appear to be related to the habitats tested,including eelgrass and adjacent unvegetated substrate,macroalgae (Ulva) and adjacent unvegetated substrate, andmarsh creek. The fastest growth occurred in shallow baysand marsh creeks. However, Malloy and Targett (1994b)suggest that juvenile growth is related to substrate or habitatin the Newport River estuary, North Carolina because of thepresence of specific prey items. The growth limitation ofjuveniles (18-80 mm TL) in one sandy-marsh habitat couldbe explained by the low abundance of mysids from May intosummer, while the increasing abundance of other prey(polychaetes and amphipods) during that same month at amuddier site may account for favorable growth seen there.Other diet studies in this estuary (Burke 1991, 1995; Burkeet al. 1991) suggest that polychaetes are actually thepreferred prey for juveniles of this size (see the Food Habitssection below).

Food Habits

The timing of peak spawning in October/Novembercoincides with the breakdown of thermal stratification on thecontinental shelf and the maximum production of autumnplankton which is characteristic of temperate ocean watersof the northern hemisphere, thus assuring a high probabilityof adequate larval food supply (Morse 1981).

Initiation of feeding is a function of the rate andefficiency at which yolk-sac material is consumed, which inturn is dependent on incubation,temperature. As reportedpreviously by Johns and Howell (1980) and Johns et al.(1981), total yolk-absorption was complete in 67 h and 105h at 21 `C and 16'C, respectively. Within those 3 to 4 daysfrom hatching, summer flounder larvae complete themorphological differentiation of the digestive tract, jawsuspension, and accessory organs necessary for independentexogeneous feeding (Bisbal and Bengtson 1995b).

To repeat the results of the Bisbal and Bengtson(1995c) study: they show the interdependence oftemperature and food availability (i.e., delay of initialfeeding) and their effects on survival and growth of summerflounder larvae hatched from Narragansett Bay and LongIsland Sound broodstock. Their laboratory observationsoccurred from the time of hatching throughout the period offeeding on rotifers. The larvae withstood starvation for

longer times at lower temperatures. They possessedsufficient reserves to survive starvation for I 1 to 12 dayswhen temperatures were maintained close to theexperimentally determined lower tolerance limit (12.5 0C;Johns et al. 1981). At temperatures close to the highestthermal limit reported to occur in their environment (2 TC;Smith 1973), larvae only survived for 6 to 7 days. At eithertemperature, best survival occurred when the larvae beganto feed at the time of mouth opening, thus survival is alsosignificantly affected by the time at which they first haveaccess to exogenous food. At 12.5°C, every treatment groupwas represented by a low number of survivors which did notgrow significantly from the initial figures at mouth opening.Growth of the larvae at 21 T was inversely proportional tothe duration of early starvation; the size distribution of thesurvivors of the 21 0C experiment showed an increase inmean size and weight when the initial feeding delay wasshorter.. Bisbal and Bengtson (1995a) also determined the

nutritional status of lab raised larvae and juveniles from thesame areas. Mortality due to starvation occurs later in theolder ontogenetic states; i.e., 60 h in 6 day old larvae, 72 hin 16 day old larvae, 8 d in 33 day old larvae, and 10 d in 60day old juveniles at a temperature of around 19'C.

In the laboratory, Peters 'and Angelovic (1971) rearedpostlarvae on a diet of zooplankton (mostly copepods) andArtemia nauplii;.Buckley and Dillmann (1982) also usedArtemia for their larval feeding experiments. The larvaeexhibited an exponential increase in daily ration with ageand a linear increase with weight (Buckley and Dillmann1982). Other investigators have raised larvae on rotifers(e.g., Bisbal and Bengtson 1995c).

Previous studies have inferred that larval and postlarvalsummer flounder initially feed on zooplankton and smallcrustaceans (Peters and Angelovic 1971; Powell 1974;Morse 1981; Timmons 1995). Grover (1998) studied thefood habits of oceanic larval flounder collected north andeast of Hudson Canyon. The diets of all stages of larvaewere dominated by immature copepodites. The size of otherprey was directly related to larval size. Preflexion larvae(1.9-6.9 mm SL) fed on, in order of importance: immaturecopepodites, copepod nauplii, and tintinnids, as well asbivalve larvae and copepod eggs. Flexion larvae (3.7-7.2mm SL) fed on immature copepodites (mostly calanoids) -

and adult calanoid copepods. Premetamorphic (4.8-7.6 mmSL) and metamorphic (5.8-9.0 mm SL) larvae also fed onimmature copepodites, but adult calanoid copepods (mostlyCentropages typicus) and appendicularians were also preyitems.

Studies on the food habits of late larval and juvenileestuarine summer flounder reveal that while they areopportunistic feeders and differences in diet are often relatedto the availability of prey, there also appears to beontogenetic changes in diet. Smaller flounder (usually <100 mm) seem to focus on crustaceans and polychaeteswhile fish become a little more important in the diets of thelarger juveniles. In Great Bay-Little Egg Harbor estuary,

New Jersey, Grover (1998) found that the primary prey ofmetamorphic (8.1-14.6 mm SL) summer flounder was thecalanoid copepod Temora longicornis, indicating pelagicfeeding. Evidence of benthic feeding was observed only inlate-stage metamorphic flounder (H+ and I), where the preyincluded polychaete tentacles, harpacticoid copepods, anda mysid. Incidence of feeding, defined as the percentage offrequency of larvae with prey in their guts, in relation to thetotal number of specimens examined in a time block,declined as metamorphosis progressed, from 19.1% at stageG to 2.9% at stage I. Rountree and Able (1992b) alsodiscovered that young-of-year summer flounder in GreatBay-Little Egg Harbor marsh creeks preyed on creek faunain order of abundance (Rountree and Able 1992a): Atlanticsilversides (Menidia menidia), mummichogs (Fundulusheteroclitus), grass shrimp (Palaemonetes vulgaris), andsand shrimp (Crangon septemspinosa) contributed mostimportantly to their diets. Seasonal shifts in diet reflectedseasonal changes in creek faunal composition, and Rountreeand Able (1992a) note that the maximum abundance ofyoung-of-year summer flounder in August coincided withthe peak in Atlantic silverside abundances. In Little EggHarbor estuary, New Jersey, Festa (1979) reported that fish,including anchovies, sticklebacks and Atlantic silversides,comprised 32.6% of the diet volume of 6-24 cm summerflounder. The fishcomponent was supplemented by mysidand caridean shrimp, of which the sand shrimp Crangonseptemspinosa was of somewhat more importance.

Timmons (1995) reported that juvenile (7.6-24.9 cmTL) summer flounder from Rehobeth Bay, Delaware; fedmostly on the shrimp Palaemonetes vulgaris as well asporturid and blue crabs. Flounder from Indian River Bayfed mostly on mysids.

Postlarvae (10.5-14.2 mm SL) in Chesapeake Bay havebeen found with guts full of the mysid Neomysis americana(Olney 1983). In Magothy Bay, Virginia, small summerflounder (4.2-19.8 cm) also fed mainly on Neomysisamericana, but in addition, consumed larger proportions ofamphipods, small fishes, small gastropod mollusks, andplant material than the larger fish (Kimmel 1973). Wyanski(1990) found that mysids were also the dominant prey of100-200 mm TL summer flounder in the lower ChesapeakeBay and. Eastern Shore of Virginia. Lascara (1981) reportedthat larger juveniles and adults (avg. length 27.4 cm SL)from lower Chesapeake Bay fed on .juvenile spot(Leiostomus xanthurus), pipefish (Syngnathusfuscus), themysid Neomysis americana, and shrimps (P. vulgaris, C.septemspinosa).

Burke (1991, 1995) in his North Carolina field surveysin the Newport and North Rivers discovered that late larvaland early juvenile summer flounder are active infaunalpredators. Prey of summer flounder during the immigrationperiod (11-22 mm SL) consisted of common estuarinecrustaceans including harpactacoid copepods, polychaetes,and parts of infaunal animals such as polychaete tentacles(primarily from the dominant spionid Streblospio benedicti)gills and' clam siphons (Figure 32). The appendages of

benthic animals appear to be the most 'important prey itemfor postlarval flounders. The increasing importance ofpolychaetes and clam siphons was suggested withdevelopment, while feeding on harpactacoid copepods andamphipods was independent of stage. For juveniles 20-60mm SL, polychaetes, primarily spionids (S. benedicti), werethe most important part of the diet (Figure 32). Burke(1991, 1995) suggests that the distribution of these dominantpolychaetes may influence the distribution of summerflounder in this estuary and could explain the movement ofjuvenile summer flounder into marsh habitat [Burke et al.1991; note the Malloy and Targett (1994b) study mentionedin the Substrate section, above]. Other prey items for thissize class of summer flounder included invertebrate parts,primarily clam siphons; shrimp, consisting of the mysidsNeomysis americana and palmonid shrimp; calanoidcopepods, primarily Paracalanus; amphipods of the genusGammarus; crabs, primarily Cqllinectes sapidus;'and fish.Powell and Schwartz (1979) reported that larger juvenile(100-200 mm TL) summer flounder feed mainly on mysids(mostly Neomysis americana) and fishes throughout the yearin Pamlico Sound, North Carolina (Figure 33). Mysids werefound in relatively greater quantities in the smaller flounder,but as their size increased, the diet consisted of shrimps andfishes in similar quantities.

In South Carolina, Wenner et al. (1990a) reported thatjuveniles between 50-125 mm TL consumed only mysidsand caridean shrimps (Palaemonetes sp., P. pugio, P.vulgaris). The importance of fish (mostly bay anchovy,Anchoa mitchilli, and mummichogs) in the diet increased assummer flounder size increased.

In Georgia, Reichert and van der Veer (1991) foundthat juveniles from the Duplin River of around < 40 mm SLfed principally on harpacticoid copepods; they also reportthat Paralichthys species > 25 mm fed on increasingnumbers of other crustaceans including mysids, crabs,Palaemonetes, as well as polychaetes. Summer flounder >100 mm also fed on fish.

Co-occurring Species and Predation

In Great Bay-Little Egg Harbor estuary in southernNew Jersey, a survey by Witting et al. (1999) from 1989-1994 showed that the fall larval fish assemblage was morediverse than any of the other seasonal assemblages, withstrong representation by summer flounder, Atlanticmenhaden (Brevoortia tyrannus), Atlantic croaker(Micropogonias undulatus), bay anchovy, and a few otherspecies.

Larval and juvenile summer flounder undoubtedly arepreyed upon until they grow large enough to fend forthemselves. Results of food habit studies by NEFSC from1969-1972 showed that Pleuronectiformes occurred in thestomachs of the following piscivores: spiny dogfish,goosefish, cod, silver hake, red hake, spotted hake, searaven, longhorn sculpin, and fourspot flounder (Bowman et

al. 1976). These data do not indicate the proportion ofsummer flounder among the flatfish prey taken, but it islikely that they are represented.

Following a thermal shock of 10°C above anacclimation temperature of 15'C, larvae were actually lesssusceptible to predation by striped killifish (Fundulusmajalis) than control larvae (Deacutis 1978).

Witting and Able (1993), working in the laboratorywith 11-16 mm TL transforming larvae from Great Bay-Little Egg Harbor, New Jersey, suggest that these smallsummer flounder are vulnerable to predation by a large sizerange of Crangon septemspinosa (around 10-50 mm TL) inNew Jersey's estuaries. Laboratory experiments by Keefeand Able (1994) in New Jersey demonstrated that predationon metamorphic summer flounder influences buryingbehavior and perhaps substrate preference. The type andabundance of predators could determine whether ametamorphic summer flounder stays in the substrate or thewater column. For example, Keefe and Able's (1994)experiments showed that buried C. septemspinosa mayreduce burying by the flounder, while pelagic mummichogsmay cause more burying by the flounder during the day.

Timmons (1995) reports a preference for sand byjuvenile (7.6-24.9 cm TL) summer flounder from the southshores of Rehobeth Bay and Indian River Bay, Delaware. Inher study, the flounder were captured near largeaggregations of the macroalgae Agardhiella tenera onlywhen large numbers of their principal prey, the shrimpPalaemonetes vulgaris, were present. Timmons (1995)suggests that the summer flounder are attracted to the algaebecause of the presence of the shrimp, but the flounderremain near the sand to avoid predation ("edge effect").Indeed, in her laboratory experiments, the juvenile summerflounder did not show a preference for the macroalgae, andin caging experiments, blue crabs were least able to prey onthe flounder in cages with sand bottoms only, but had anadvantage in capturing the flounder in cages containingmacroalgae. Laboratory studies by Lascara (1981) onflounder from lower Chesapeake Bay also suggest that inpatchy seagrass/sand habitats, the flounder may avoidpredation by staying in the sand near the seagrass beds,rather than in the grass beds themselves.

Lab studies in Georgia by Reichert and van der Veer(1991) on juveniles from the Duplin River found potentialpredators to be blue crabs (Callinectes spp.) and sea robins(Prionotus spp.).

ADULTS

Temperature

NEFSC groundfish data shows a seasonal shift inoffshore adult summer flounder occurrence with bottomtemperatures (Figure 34): most adults are caught over arange of temperatures from 9-260C in the fall, from 4-13 0C

in the winter, from 2-20'C in the spring, and from 9-27'C inthe summer. Massachusetts inshore trawl survey data alsoshows a seasonal shift in adult occurrence with bottomtemperature (Figure 30). In the spring, most adults occur ata range of temperatures from 6-17"C, while in the fall theyoccur at temperatures from 14-21"C. Prior to 1979,Sissenwine et al. (1979) reported that NEFSC trawl surveyson the continental shelf showed that the distribution ofsummer flounder by depth was related to their temperaturedistribution. During spring they were distributed widelyover the continental shelf, from 0-360 m depth (comparewith Figure 4), and primarily in waters between 8-16'C.During summer the flounder were primarily captured indepths of less than 100 m, and in waters between 15-28TC.The autumn distribution was also at depths of less than 100m and temperatures between 12-28'C. During winter, theygenerally were found at depths greater than 70 m, and attemperatures between 5-I1 TC (Sissenwine et al. 1979).

Based on collections from the 1990-1996 Rhode IslandNarragansett Bay survey, adults were distributed throughoutthe Bay and captured in all seasons except winter; in springthey were found in bottom temperatures above 6'C andbelow 15'C in autumn (Figure 35). By summer the adultsoccurred at nearly all temperatures and in autumn they wereconcentrated where temperatures exceeded 17'C.

In the Mid-Atlantic Bight north of Chesapeake Bay,spawning and the offshore limits of migration coincide withthe inshore edge of the mass od cold bottom water thatdisappears along with the thermocline in November (Smith1973).

A study by Stolen et al. (I 984a) compared the effect oftemperature on the humoral antibody formation in thesummer and winter flounder at 8, 12 and 17'C during thesame time of the year. Summer flounder showed only adelay in the appearance of circulating antibody at lowertemperatures while winter flounder showed both a delay anda marked suppression at lower temperatures. Summerflounder produced a high titered antibody that persisted overa long period of time and over a wide temperature range,while in winter flounder antibody levels began decreasingafter one month.

A similar, study on the kinetics of the primary immuneresponse in summer flounder was also studied by Stolen etal. (1984b). The flounder produced antibody over a widerange of environmental temperatures ranging from 7.5-270 C.At the lower environmental temperatures, a correspondingdelay in the appearance of circulation antibody occurred,although the magnitude and duration of the response was notappreciably affected. After immunizing at 12"C, loweringthe environmental temperature gradually to 8"C did notappear to inhibit an ongoing primary response. Typicalsecondary responses were seen in fishes kept at warmertemperatures, but when the temperature was lowered to 8'C,no anamnestic response was seen. Individual variation wasmost noticeable at middle temperature ranges.

Salinity

Adult summer flounder return inshore to coastal watersin April through June, and are often found in the highsalinity portions of estuaries [e.g., Abbe (1967) in Delaware,Tagatz and Dudley (1961) and Powell and Schwartz (1977)in North Carolina; Dahlberg (1972) in Georgia]. However,the adult summer flounder's distribution may be due more tosubstrate preference than salinity preference.

Dissolved Oxygen

Effects of dissolved oxygen concentration on summerflounder adults has not been investigated (Rogers and VanDen Avyle 1983). Festa (1977) reported that the highvariability in catch rates of summer flounder off of NewJersey in the summer of 1976 appeared to be directly relatedto the movement of an anoxic water mass present that year.Large numbers of summer flounder were forced into inletsand bays where they were more concentrated and vulnerableto the sport fishery (Freeman and Turner 1977).

Light

Laboratory studies (Olla et al. 1972; Lascara 1981) andfield collections (Orth and Heck 1980) indicate that adultsummer flounder are active primarily during daylight hours.To repeat .what was stated above for juveniles: laboratorystudies by Lascara (1981) on juveniles and adults fromlower Chesapeake Bay showed that peak feeding activity(search-pursuits/unit time) generally occurred duringdaylight hours between 0800 and 1200.

Water Currents


Substrate/Shelter

Adults have often been reported as preferring sandyhabitats (Bigelow and Schroeder 1953; Schwartz 1964;Smith 1969). For example, in Pamlico Sound, NorthCarolina, Powell and Schwartz (1977) found that summerflounder were most abundant at stations where quartz sandor coarse sand and shell predominated. In Barnegat Bay,New Jersey, Vouglitois (1983) suggests that both juvenileand adult summer flounder are found in greater numbers inthe eastern portion of the Bay, where sandy sedimentspredominate. However, adults can camouflage themselvesvia pigment changes to reflect the substrate (Mast 1916).Thus, they can be found in a variety of habitats with bothmud and sand substrates, including marsh creeks, seagrass

beds, and sand flats (Bigelow and Schroeder 1953; Dahlberg1972; Orth and Heck 1980; Lascara 1981; Rountree andAble 1992a).

As previously explained above in the Section onjuveniles, laboratory experiments by Lascara (1981) onlarger juveniles and adults from lower Chesapeake Bayfound that flounders appear to utilize eelgrass beds as'blinds'; i.e., they lie-in-wait along the vegetative perimeter,effectively capturing prey which move from within the grass.Lascara (1981) concludes that the ambush tactics of summerflounder are especially effective when the flounder are inpatchy habitats where they remain in the bare substrate(sand) between eelgrass patches. Lascara (1981) also notedthat if flounder remained within densely vegetated areas,they would probably be conspicuous to prey because, in hislaboratory experiments, as the flounder moved through thevegetation, the grass blades were matted down andessentially "traced out" their body shape. The floundermight also be conspicuous to potential predators as well,suggesting the "edge effect" hypothesis of Timmons (1995).Thus, the flounder remain near the sand to both avoidpredation and conceal themselves from prey.

Food Habits

Adult summer flounder are opportunistic feeders withfish and crustaceans making up a significant portion of theirdiet (Figure 36). Differences in diet between habitats orlocations may be due to prey availability. The flounder aremost active during daylight hours and may be found well upin the water column as well as on the bottom (Olla et al.1972). Included in their diet are: windowpane (Carlson1991), winter flounder, northern pipefish, Atlanticmenhaden, bay anchovy, red hake, silver hake, scup,Atlantic silverside, American sand lance, bluefish, weakfish,mummichog, rock crabs, squids, shrimps, small bivalve andgastropod mollusks, small crustaceans, marine worms andsand dollars (Hildebrand and Schroeder 1928; Ginsburg1952; Bigelow and Schroeder 1953; Poole 1964;,Smith andDaiber 1977; Allen et al., 1978; Langton and Bowman1981; Curran and Able 1998).

In Little Egg Harbor estuary, New Jersey, Festa (1979)reports that at least seven species of fish occurred in thestomachs of 25-65 cm summer flounder. These includedAtlantic silversides, anchovies, sticklebacks, silver perch,sea robins, winter flounder and pipefish. Fish remainscomprised 74.3% of.the diet volume. Brachyuran crabs,primarily Callinectes, were of secondary importance in thediet. In Hereford Inlet near Cape May, New Jersey, Allenet al. (1978) found that adult and juvenile summer flounder(200-400 mm) fed mostly on Crangon septemspinosa,mysids and fish.

Smith and Daiber (1977) reported that Delaware Bayadults < 45 cm TL fed on invertebrates, while those > 45 cmTL ate more fish. Food items found, in order of percentfrequency of occurrence, included decapod shrimp

(Crangon septemspinosa), weakfish (Cynoscion regalis),mysids (Neomysis americana), anchovies (Anchoa sp.),squids (Loligo sp.), Atlantic silversides (Menidia menidia),herrings (Alosa sp.), hermit crabs (Pagurus longicarpus),and isopods (Olencira praegustator).

In Magothy Bay, Virginia, large summer flounder(20.1-47.6 cm) fed mainly on Neomysis americana, as wellas large crustaceans such as Squilla empusa, xanthid crabs,and squids. The fish from this area are not mainlypiscivorous, but the larger specimens (> 40.0 cm) didcontain a higher percentage of fishes than did the smallerones (Kimmel 1973). Lascara (1981) reports that largerjuveniles and adults (avg. length 27.4 cm SL) from lowerChesapeake Bay fed on juvenile spot (Leiostomusxanthurus), pipefish (Syngnathus fuscus), the mysidNeomysis americana, and shrimps (P. vulgaris, C.septemspinosa).

In South Carolina, Wenner et al. (1990a) showed thatflounder 50-313 mm TL consumed mostly decapodcrustaceans, especially caridean shrimps (Palaemonetes sp.,P. pugio, P. vulgaris). The importance of fish (mostly bayanchovy, Anchoa mitchilli, and mummichogs) in the dietincreased as summer flounder size increased.

Co-Occurring Species and Predation

Spatial co-occurrence and dietary overlap amongsummer flounder, scup, and black sea bass have beenpreviously documented (Musick and Mercer 1977; Gabriel1989; Shepherd and Terceiro 1994). For example, thecomposition and distribution of fish assemblages in theMiddle Atlantic Bight was described by Colvocoresses andMusick (1979) by subjecting NEFSC bottom trawl surveydata to the statistical technique of cluster analyses. Summerflounder, scup, northern sea robin, and black sea bass, allwarm temperate species, were regularly classified in thesame group during spring and fall. In the spring this groupwas distributed in the warmer waters on the southern shelfand along the shelf break at depths of approximately 152 m.During the fall this group was distributed primarily on theinner shelf at depths of less than 61 m where they were oftenjoined by smooth dogfish.

All of the natural predators of adult summer flounderare not fully documented, but larger predators such as largesharks, rays, and goosefish probably include summerflounder in their diets.

Laboratory studies by Lascara (1981) on flounder fromlower Chesapeake Bay suggest that in patchy seagrass/sandhabitats, the flounder may avoid predation by staying in thesand near the seagrass beds, rather than in the grass bedsthemselves.

INSHORE SUMMER FLOUNDERHABITAT CHARACTERISTICS

Habitat information is meaningful because habitatdifferences can be important in determining localabundances of summer flounder (Cadrin et al. 1995).Because most of the summer flounder habitat researchoccurs inshore, Tables 2-4 present the inshore habitatparameters or requirements for summer flounder found innearshore New Jersey, Delaware, and North Carolina,respectively. Those States were chosen because of theamount of the high quality, habitat related research onsummer flounder occurring there [by highest quality wemean Level 3 information as defined in the EFH TechnicalManual (National Marine Fisheries Service, Office ofHabitat Conservation 1998) and Interim Final Rule(Department of Commerce, National Oceanic andAtmospheric Administration 1997)]. Thus, we have alsochosen to concentrate on studies (experimental or otherwise)which focus on the habitat parameter preferences, and arefrom published, peer-reviewed literature sources, rather thanon information that merely attempts to correlateenvironmental variables with fish densities, such as thatwhich often appears in general fisheries surveys. We heedthe advice of Hettler et al. (1997), who suggest cautionwhen interpreting correlations of environmental variableswith fish abundances. For example, they reported anincrease in summer flounder larval abundance withincreasing temperatures in Beaufort Inlet, North Carolina.This could be caused by winter spawning and the larvaearriving at the inlet after a two to three month cross-shelftransport time, resulting in a higher larval abundancecorresponding with rising temperatures. Their statisticalanalyses suggest that unknown factors are probably moreimportant in causing peaks in the abundances of immigratinglarvae (see also Hettler and Hare 1998).

Table 5 is a summation and synthesis of Tables 2-4, andshould provide an overall, yet more succinct view of currenthabitat requirements information on inshore summerflounder. The habitat parameter headings for all the tablesare based upon those used in the Habitat Characteristicssection, above.

STATUS OF THE STOCKS

The following section is based on Terceiro (1995) andthe Northeast Fisheries Science Center (1997). Thecoverage is from New England to Cape Hatteras.

The stock is at a medium level of historical (1968-1996) abundance and is over-exploited. The age structureof the spawning stock has begun to expand, with 34% of thebiomass at ages 2 and older in 1996, although underequilibrium conditions about 85% of the spawning stockbiomass would be expected to be ages 2 and older. The1995 year class is about average (1982-1996), but the 1996year class is estimated to be the smallest since the poor year

class of 1988.Commercial landings of summer flounder averaged

13,200 mt during 1980-1988, reaching a high of 17,100 mtin 1984 (Figure 37). The recreational fishery for summerflounder harvests a significant proportion of the total catch,and in some years recreational landings have exceeded thecommercial landings. Recreational landings havehistorically constituted about 40% of the total landings.Recreational landings averaged 9,800 mt during 1980-1988,and peaked in 1983 at 12,700 mt. During the late 1980s andinto 1990, landings declined dramatically, reaching 4,200 mtin the commercial fishery in 1990 and 1,400 mt in therecreational fishery in 1989 (Table 6). Reported 1996landings in the commercial fishery used in the assessmentwere 5,770 mt and estimated 1996 landings in therecreational fishery were 4,704 mt (Table 6).

Spawning stock biomass declined 72% from 1983 to1989 (18,900 mt to 5,200 mt), but has since increased withimproved recruitment to 17,400 mt in 1996 (Figure 37;Table 6). The age structure of the stock is improving, with34% of the spawning biomass in 1996 composed of fish ofages 2 and older, compared to only 17% in 1992.

Figure 38 shows the contrast between the distribution ofsummer flounder from periods of high abundances in thepast (1974-1978) to recent periods of low abundances(1989-1993), for both adults and juveniles in the fall andspring.

RESEARCH NEEDS

Obviously, there are many gaps in our understanding ofthe autecology of summer flounder. Because it is such ahighly migratory species and occurs everywhere throughoutits range, knowledge of its life history and habitatrequirements can vary regionally, and what affects them inone area can easily cause repercussions in the population inanother area. Even though summer flounder is managed andassessed as one stock throughout the U.S. EEZ, the questionof multiple stocks, particularly in the Mid-Atlantic Bight,still needs to be settled from a scientific standpoint. Thereis a lack of knowledge concerning the habitat requirementsfor all life history stages, especially the offshore eggs andlarvae, but even for the adults within our own estuaries,since much of the current habitat research has focused onestuarine larvae and juveniles (note Tables 2-5). Of course,more habitat information is needed on the inshoretransforming larval and early juvenile stages, especiallybecause their health affects the future growth and survival ofthe population. Finally, critical habitat preferences must bedefined. For example, while it is likely that temperature maydrive the seasonal movements of juveniles and adults in andout of the estuaries, it may have less effect on their choice ofspecific habitats within those estuaries, where substrate,salinity, etc. may be the overriding factors. Once theirhabitat preferences are defined, their critical habitats can bemore thoroughly delineated and mapped.

ACKNOWLEDGMENTS

This paper was originally presented as a rewrite of thehabitat section of the summer flounder FMP withamendments [Mid-Atlantic Fishery Management Council(MAFMC) 1987, 1991].

The authors wish to thank Mark Terceiro, AnneStudholme, and Jeff Cross for reviews and editorialassistance, and Rande Ramsey-Cross, Judy Berrien, ClaireSteimle, and Ferdinand Triolo for library assistance. MarkTerceiro provided the status of the stocks report. RodneyRountree provided the original food habits data from theNEFSC trawl surveys with which Joe Vitaliano generatedthe pie charts. Frank Almeida provided much NMFS dataand associated methodology and assisted with the figurecaptions.

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Table I. Presence of summer flounder inshore, by State, as documented by authors cited in the text and personalcommunications from each States' flounder experts.

Author [Location Jan IFeb IMar Apr May Jun IJul [Aug ISep Oct INov IDec Notes

Howepersonalcommunication

Smithpersonalcommunication

Poole 62

Szedlmayeret al. 92

MAshoals s. ofCape Cod& Cape Cod Bay

CT

Long IslandSound

NY

Great SouthBay, Long Island

NJ

Great Bay,Little Egg Harbor

AE IEEEEEEEEEEEEEE EEEEEEE

A A: peak /B

tEH lit B I I It

It --- *1/

AEEEEEEE

EE

EEEEEEE

Hereford Inlet,Allen etat. 78 near Cape May

Murawski 70

Festa 74

Keefe and Able

93

Sandy Hook &Cape May

NJ estuaries;Sandy Hookto Great Bay

NJ estuaries

TL

L/TL

TL

llllllflllilllI llltll11If l

J

TL

TLH11 HT1111111

A

J,A

tIltIttlltIt 1 - - !EEEEEEE

lllllmIIIlIII

mean length38cm

TL: 11-17mm,J: YOY,60-326mm

TL: 12-15mmJ/ A: 200-400m

A: 230-700mm

Il.L 5-21mm;enter est. earlyOct-late Janmost yrs, as lateas March

TL: 10-15mm,most abundantOct-Dec

J: YOY,160-320mm TL

ULnIIIIIIIIIIIII[llliulml] Ilannllulll IIHHIIIIIIII llllllllllllll

TLHHtlmHlIIIIllHHttmtH

Able et al. 90 NJ estuaries J: peak IEEEEEEEIEEEEEEEIEEEEEEE EBEEEEEEIEEEEEEE

i

presence L larvaepeak abundance TL transforming larvae

- limited numbers J juvenilesIIIIIIIIII peak ingress A adultsIflltItIl] ingressEEEEEE egress

Table I. cont'd.

Author Location Jan Feb Mar Apr May Jun Jul Auci Sep Oct Nov Dec NotesDE

Smith personal Delaware Bay A A: peak somecommunication -.......--- - .-- .---- -- 'adults

present allyear

Smith and Delaware Bay J/A: peakDailer 7 . .. . . . .. .some

Daiber77 juveniles

present indeep partsof bayevery wintemonth

VAMusick Eastern Shore & J In milderpersonal lower -. tttttttttttt -ttttttttttt- -EEEEEEE EEEEEEE - - - winterscommunication Chesapeake Bay some age

1+ fishremain inbay

Eastem Shore, Aseaside tttttttttttt EEEEEEEinlets/lagoons

lower AChesapeake Ba tttttttt EEE EEE

Wyanski 90 both sides of J peakEastern Shore Ill/llllIllllll llllll lllllllIIIIIIIIIII flllllll recruitment

Nov-Decwestern J peakChesapeake Ba tttttttttttttt I/I/11/1111/I IIIIII1111111 recruitment

March-April

presence L larvaepeak abundance TL transforming larvae... - limited numbers J juveniles

HIIIIIIIII peak ingress A adultstttttttttttt ingressEEEEEE egress

Table 1. cont'd.

Author Location Jan . Feb Mar ADr May Jun Jul Aug Sep. Oct' Nov Dec Notes

NC

Hettler and Oregon Inlet, TL TL: peak ingressBarker 93 TLOcracoke Inlet IIIII11/111

J J=YOY, present

Powelland -18-20 mos. from

Schwartz 77 Pamlico sound mid winterrecruitment to -Auof 2nd yr.

Newport River, TLBurkeoet al. 91 North River HIIIIH I TL = 11-17mm SL

estuaries

Monaghanpersonal Beaufort Inlet TLcofuiajoIIlllllllI TL: peak ingresscommunicatior /

Tagatz and .fTIJle"T/=180

Dudley 61 Beaufort tntet 11JJ=11-l80mm

TL

Weinstein 79 Cape Fear Rive TL = 9-16mm SL

SC

Wenneret al Charleston TIlJJ

90a Harbor & vicinitt TLJ = 10-20mm T

presence L larvaepeak abundance TL transforming larvae

- - - limited numbers J juvenilesIIIIIIIIII peak ingress A adultsttttttttttlt ingress

EEEEEE egress

Table 2. Habitat parameters for summer flounder, Paralichthys dentatus: inshore New Jersey.

Life Stage Authors Size Range Geographic Time Period Habitat Substrate TemperatureLocation

TRANSFORMING Grover 1998 8.1-14.6 mm Great Bay, Little Fall, winter, Little SheepsheadLARVAE SL Egg Harbor spring 89-95 Creek

(metamorphic)

Keefe and 10-15.6 mm Great Bay, Little Nov 90-Nov 91 Little Sheepshead Sand preference Increased temps. =Able 1993, SL, mean 12.8 Egg Harbor. Nov 90-Mar 91 Creek by both shorter metamorphic1994 (metamorphic) metamorphs and period. Greater

juveniles. mortality at 4"C. Noeffect of starvationon mortality or timeto completion ofmetamorphosis attemps. < 10"C.

Szedlmayer et 11-17 mm TL Great Bay, Little Nov 88-Apr 89 0-13'C, mortalityal. 1992 (metamorphic) Egg Harbor < 2oC

Witting and 11-16 mm TL Great Bay, Little Jan-Feb 90 9-12'CAble 1993 (metamorphic) Egg Harbor

JUVENILES Rountree and mean 132 mm Great Bay, Little Apr-Nov 88 Schooner, New, mud mean 19'CAble 1992a SL (YOY), Egg Harbor Apr-Oct 89 Foxboro creeks

range ca.16-245 mm

Rountree and mean 238 mm Great Bay, Little 1987-1990 Schooner, New, mud mean 22'C, rangeAble 1992b TL (YOY). Egg Harbor Foxboro, Stoney 15-27"C

range creeks156-312 mm

Rountree and mean 192 mm Little Egg Harbor May/July-Nov 90 Foxboro, Stonely mudAble 1997 SL, range 138- Island creeks.

390 mm, Marsh creeks andmostly YOY deeper (4-9 m) bay

shoals.

Szedlmayer et 60-326 mm TL Great Bay, Little June-Sept 89 June: mesohaline subtidal creeksal. 1992 (YOY) Egg Harbor subtidal creeks 90-98% mud

July: shallowmudflats/dredgedchannelsAug-Sept: marshcreeks

Szedlmayer 210-254 mm Great Bay, Little Aug-Sept 90 Schooner Creek mean 23.5'Cand Able TL Egg Harbor (optimum?)1993 (age 0)

' Laboratory studyAdults: no pertinent informainon

Table 2. cont'd.

Life Stage Authors Salinity Dissolved Light Currents Prey Predators NotesOxygen

Primary prey: calanoidTRANSFORMING Grover copepod Temora

LARVAE 1998 longicornis, indicatingpelagic feeding. Evidenceof benthic feedingobserved only in late-stagemetamorphs (stage H+ andI), where prey includedpolychaete tentacles,harpacticoid copepods.

Less burying inKeefe and Prefer Increased presence of decapod Time to completionAble 1993, burying burial at shrimp Crangon, of metamorphosis1994 during flood tide. increased burying in temperature

daylight. presence of dependent.mummichogFundulum.s

Szedlmayeret al. 1992

11-16 mm TLWitting and transforming larvaeAble 1993 are vulnerable to

predation by a largesize range of shrimp(Crangonseptemnspinosa, - 10-50 mm TL) in NJestuaries.

Found mostly duringJUVENILES Rountree mean 29 ppt summer. Abundance

and Able varied significantly1992a between years.

Maximumabundance of flukeduring peak inMenidia menidiaabundances.

Moving In order of abundance: Creeks are foragingRountree mean 27ppt, with the Atlantic silversides habitat. Preyand 1992b range 23.5- tides. Tidal Menidia menidia, composition exhibits

30 ppt movements mummichogs Fundulus a seasonal influence.associated heteroclitumv, shrimps Frequency ofwith Palaemonetes vulgaris Menidia declinesforaging - and Crangon during Aug, Sept,stomachs .septemspinosa. Oct while Crangonfuller on rises.ebb tide.

NocturnalRountree range 22-33 sampling: Mostly Preference for creekand Able ppt extensive caught on mouths and tidal1997 use of ebb tides creeks rather than

shallow (sampling bay shoals. Peakhabitats during night catch in lateduring hours). July/Oct.night-time.

Szedlmayer subtidal High use of creeket al. 1992 creeks avg. mouths.

20 pptSelective tidal

Szedlmayer mean 29 ppt mean 6.4 selective transport, feeding,and Able (optimum?) ppm tidal stream optimal1993 (optimum?) transport environmental

conditions causemovement. High useof creek mouths.

Laboratory studyAdults: no pertinent information

Table 3. Habitat parameters for summer flounder, Paralichthys dentatus: inshore Delaware.

Life Stage Authors Size Range Geographic Time Period Habitat SubstrateLocation

JUVENILES Malloy and Collected 41-80 Roosevelt Inlet and Inlet: Nov 89-Apr 90 Estuarine marsh creeksTargett 1991 mm TL for Indian River Bay Bay: Feb-June 89-90 0.5-1.5 m in depth.

experiment.

Malloy and 18-80 mm TL Indian River Bay Jan-June 91/92Targett 1994a

Malloy and 18-80 mm TL Indian River Bay Jan-June 92 Protected beach close to Intermediate size grainsTargett 1994b muddy channel, with ephemeral

macroalgal cover.

Timmons 7.6-24.9 cm TL Rehoboth Bay, June 92, Aug 92, Attracted to the algae Prefer sand to shell1995 Indian River Bay Nov 92, Mar 93 Agardhiella tenera rubble or algae. I

because of the presence Captured in sand andof prey, but remain in mud.nearby sand to avoidpredation. Collected inwater depths between0.5-5.5 m.

ADULTS Smith and > - 28 cm TL Delaware Bay Aug 66-Nov 71. Captured from theDaiber 1977 Most captured May- shoreline to 25 m deep.

Sept, a few[juveniles] have beencaught in the deeperparts of the Bay inevery winter month.

Laboratory study

Transforming larvae:,no pertinent informationDO., Currents. Light: no pertinent information

Table 3. cont'd.

Life Stage Authors Temperature Salinity Prey Predator Notes

Mortality was 42% afterJUVENILES Malloy and 16 days at 2-3°C; > 3oC, Collected at 24-30 Fed locally caught mysid The extended period Juveniles that

Targett 1991 all fish survived. ppt. Experimental shrimp Neomysis americana in of time spent at small arrive in northernMortality highest in fish < salinity variation experiment. sizes may increase Mid-Atlantic50 mm TL in < 3YC water: (10-30 ppt) had vulnerability to Bight estuaries inall fish > 65 mm survived no effect on predation. the fall, in< 2.5"C for 2 weeks, feeding, growth or advance of winterGrowth rates were the survival. temperaturesame between 2 and I0"C. minima, may beMean growth rate able to grow pastincreased to 2.4% per day a lower criticalat 14"C and 3.8% per day size, thusat 18'C. increasing

survival.

Mortality ofjuveniles Can survive 14 days with noMalloy and depends more on rate of food at 10-16"C (typicalTargett temperature decline than temperature at settlement).1994a on final exposure Prey availability is important

temperature. No growth at to growth, Fed locally caughttemperatures mysid shrimp N. americana in< 9"C. DE fish more experiment.tolerant of lowtemperatures (1 -4"C) thanNC fish.

Low densities of mysids (one Extended period ofMalloy and 2.6-20"C of the dominant prey items) time spent at small < 50% maximumTargett until June. sizes (13-25mm TL) growth in1994b could increase May/early June.

vulnerability topredation.

Timmons June: 22-281C, Range: 12-28 ppt. Rehoboth flounder fed on In caging experiments, Suggests that1995 August: 17-25'C, Salinities were shrimp Paleomonetes blue crabs were least macroalgal

November: 7-12"C, constantly lower vulgaris, plus porturid and able to prey on the systems appear to

March: 9-13"C in Indian River blue crabs. Indian River fish flounder in cages with act as anBay compared to fed on mysids. sand bottoms only, but ecologicalRehoboth Bay. had an advantage in surrogate to

capturing the flounder seagrass beds andin cages containing seagrass/macro-macroalgae.1 algal systems.

< 45 cm fed on invertebrates,ADULTS Smith and > 45 cm TL ate more fish. In Appear to migrate

Daiber 1977 order of % frequency of little and may beoccurrence: shrimp (C. permanentseptemvpinoso), weakfish, residents.mysids (N. americana),anchovies, squids, Atlanticsilversides, herrings, hermitcrabs (P. longicarpus),

_isopods (0. praegusta).

Laboratory studyTransforming larvae: no pertinent informationD.O., Currents, Light: no pertinent information

Table 4. Habitat parameters for summer flounder, Paralichthys dentatus: inshore North Carolina.

Life Stage Authors Size Range Geographic Time Habitat Substrate TemperatureLocation Period

Wild caught and labTRANS- Burke 1991 mean 14.7 Newport River Feb-Mar 87- reared larvae: preferred 6-20'CiFORMING mm SL Estuary 89 sand over mud evenLARVAE when prey not present.

Implies search for foodto some extentrestricted to sandysubstrate in settlingfish.

Burke 1995 11-20 mm SL Newport and Jan-Apr 88 Tidal flats, channels. 10-13'CNorth River

Larvae concentrate on Substrate type canBurke et al. 11-17 mm SL Newport and Nov-Apr 86- shallow tidal flats (< I m), affect distribution.1991 North Rivers 89 middle reaches of estuary. Higher probability on

Fewer catches in "1.5-3 m. sand than mud.In spring juveniles migrateto higher salinity saltmarsh.Onslow Bay: concentrate

Burke et al. Onslow Bay: Onslow Bay, Feb/Mar in estuarine areas. Outside1998 9-15 mm SL, includes 1995 the estuary in the surf zone

transforming nearshore and in deeper habitats oflarvae, waters; the Bay, larvae wereBeaufort Beaufort Inlet present only during theInlet: 11-15 and Newport . immigration season.mm SL, all at River estuary. Within the Newportstages estuary initial settlementG - 12. appears to be concentratedNewport in the intertidal zoneRiver estuary: rather than in adjacent11-21 mm deeper areas.SL.

Deubler and 12-15 mm SL Bogue Sound Feb-61White 1962

7-18"C, higherHettler et al. 12-15 mm SL Beaufort Inlet Nov 91-Apr Tidal channel, 6m deep. abundance with1997 92, nightly increased

temperatures.Tidal salt marsh and

Weinstein et 7-34 mm SL Cape Fear Mar-Apr creeks, shallow openal. 1980a River Estuary water.

Grain size variation 16.8-21.1]CWeinstein et mean 13.6 Cape Fear Sept 77-Aug Tidal creeks, shallow among sites: fine sandal. 1980b mm River Estuary 78 marsh. (58-93%), medium

sand (7-41%), mud (I-14%).

Pamlico Sound, 1957-1966, 2-22"C, mostWilliams Neuse River biweekly, at abundant at 8-and Deubler night 16'C.1968b

Laboratory studyAdults: no pertinent informaitionD.O.: no pertinent information

Table 4. cont'd.

• Life Stage Authors Size Range Geographic Time Habitat Substrate TemperatureLocation Period

Tidal flats andJUVENILES Burke 20-60 mm SL Newport and Jan-Apr 88 channels, juveniles 10-133C

1991, 1995 North Rivers migrate to salt marsh.Shallow: < 1 m meanlow tide.

2-20'C: Increase inMalloy and 18-80 mm TL lower Newport Jan-June temperature = increase inTargett River 91-92 feeding rate, maximum1994a growth rate, gross growth

efficiencies. Increasedrate of temperaturedecline = decreasedsurvival.< 7-9'C no positivegrowth rates.

Sandy salt marsh Predicted growth ratesMalloy and 18-80 mm TL Newport River Jan-June (adjacent to Spartina higher at muddy beach 8-23°C (Feb-June)Targett Estuary 92 alterniflora marshes) site in May.1994b and muddy beach.

10-30"C, increase inPeters and temperature = increase inAngelovic ad libitum feeding rate1971 and growth efficiency.

Little growth at lowtemperatures, fastestgrowth rate at 20-25'C.Specific growth rate5% at 15'C, 10% at20'C.'Migration to estuary in

Powell , 18-224 mm Pamlico Sound May 71- February: body weight1982 TL, mean at July 72 increases 5%/day. After

end of I st yr: February increase inmales 167 temperature = a decreasemm, females in growth rates. Late fall171 mm TL growth negligible. June:

2% increase body weight/day, August: 1%.

Range 70-250Powell and mm TL. 8-16 Pamlico Sound Aug 71- Most abundant in Greater abundance with Warm temperatures andSchwartz mm when July 72 eastern and central sand, or sand/shell, intermediate/high1977 entering Pamlico Sound scarce where mud salinities = increased

estuary, 90- (relatively high predominates. growth rate.100 mm at salinity), close to inlets.first spring,Ist yr.

juveniles 170mm by Dec.

Aug 71-Powell and 100-400 mm Pamlico Sound July 72, Dominant in lower Increased temperatures =Schwartz TL (84% of and adjacent monthly, estuary. increased food1979 captures 100- estuary daylight consumption for

200 mm TL) sampling overwintering juveniles.

Ross and 21-320 mm Pamlico Sound Mar 81- YOY on seagrass bed. fine sandEpperly SL Nov 821985

Laboratory studyAdults: ,to pertinent informationD.O.: no pertinent information

Table 4. cont'd.

Life Stage Authors Salinity Light Currents Prey Predators Notes

TRANS- Burke 1991 16-34 ppt r Sand preference ofFORMING metamorphosing larvae inLARVAE laboratory corresponds to older

fish in wild.Burke 1995 21-32 ppt Polychaete tentacles

most important, pluspolychaetes andharpactacoidcopepods. Increasingimportance ofpolychaetes andclam siphons withincreasingdevelopment.

PredatorBurke et at. 19-31 ppt avoidance by1991 burying in

sandysubstrate.

During flood tides, highest Observations of tidal rhythm ofBurke et al. -31-34 ppt larval densities at mid-depths activity of wild-caught flounder'1998 within water column; during and vertical shift into water

ebb tide, highest densities at column during slack tide suggestsbottom. Position in water behavioral component to tidalcolumn dependent on tidal stream transport. High activitystage; shift in during ebb tide' suggests mostdistribution/abundance active behavioral component ofassociated with shift in tidal TST involves avoidance ofstage, indicating flounders enter advection by ebbing tide ratherOnslow Bay by tidal stream than movement into water columntransport. Wild-caught larvae and transport by flood tide. Lackhad regular paitern of activity of tidal activity pattern in lab-correlated with tidal cycle; peak reared flounder' suggestsactivity associated with ebb development of tidal rhythmtide'. Lab-reared flounder: no dependent on exposure toclear pattern of activity

t. physical variables that are

correlated with the tide.Deubler and 10-30 ppt: Salinities commonly found inWhite 1962 increase in lower estuary allows optimal

salinity = growth.increase inbody wt; 40ppt =decrease inbody wt. I

Hettler et 24-36 ppt More abundant mean density = 2 larvae/100m"•at. 1997 in catches later (Dec 31-Apr 15)

at night.Weinstein Night catches > Marsh migration aided by Despite intensive tidal flowset al. 1980a day catches. At surface movement on flood tides maintain preferred position in

night at night, settle to bottom on ebb. estuary by specific behavioralconcentration at responses.surface >concentration atother depths.

Weinstein 1.7-24.9 Distribution influenced by salinityet al. 1980b ppt; greater gradients and to lesser extent by

occurrence substrate characteristics.inmid/highersalinities.

Williams .02-35 ppt.and Deubler IS ppt1968a optimum _ I

Laboratory studyAdults: no pertinent informationD.O.: no pertinent information

Table 4. cont'd.

Life Stage Authors Salinity Light Currents Prey Predators Notes

Visual Active predator; ate Diets of summer and southernJUVENILES Burke 21-32 ppt predators. primarily infaunal flounder similar during settlement

1991, 1995 Feeding crustaceans, polychaetes, when distributions overlapped. Dietslargely invertebrate parts. diverged prior to segregatedrestricted Polychactes (primarily distribution. Spionid preyto daylight. spionids) most important. Streblospio benedicti abundant in

marsh; may explain juvenilemigration to marsh.

NC juveniles higher maximumMalloy and 30 ppt Winter food limitation less growth rates and growth efficienciesTargett important than variability of than DE fish at temperatures from 6-1994a temperature minima. 180C. NC fish less tolerant of low

temperatures (I -4'C) than DE fish.Low abundance of NC

Malloy and mysids from May into Predicted growth rates = 2-5%/dTargett summer might explain Feb-April. Marsh juveniles severely1994b growth limitation in marsh growth limited after April with

juveniles during May. temperatures 18-20'C.Increasing abundance ofother prey (polychaetes,amphipods) may accountfor favorable juvenilegrowth in muddier siteduring May.

Maximum caloric growth efficiencyPeters and 5-35 ppt;. predicted at 21'C, 24ppt salinityAngelovic relatively little and 78% ad libitum feeding. All1971 effect on ad body processes including feeding

libitum feeding increases with temperature to anrate.' optimum; > optimum, increasing

temperature becomes detrimental.Decrease in growth with increase in

Powell temperature probably due to intrinsic1982 (not environmental) factors.

Most abundantPowell and moderate/high Shallow Juveniles overwinter in estuarySchwartz salinities 18-35 waters near (adults migrate to ocean).1977 ppt. Spatial inlets (fast Distribution governed primarily by

segregation flowing). benthic substrate and salinity.with southern Pamlico Sound unusual: solar-lunarflounder: tides immeasurable; salinitiesincrease in uniform in much of sound.salinity =increase insummerflounderabundance.

Young flounder fed mostlyPowell and Dominant in on mysids and fishes Southern flounder diet compared:Schwartz higher throughout the year. As size reverse importance was found -1979 salinities. increases diet consisted of fishes, then mysids.

shrimps and fishes insimilar quantities. Feedingrate decreases in winter.

DistributionRoss and significantlyEpperly correlated with1985 salinity, range

22-28 ppt,optimal 22-23

_ ppt.

' Laboratory studyAdults: no pertinent informationD.O.: no pertinent information

Table 5. Summary of life history and habitat parameters for summer flounder, Paralichthys dentatus: inshore NewJersey, Delaware and North Carolina.

Life Stage Size Geographic Habitat Substrate TemperatureLocation.

TRANSFORMING - > 8 - < -18 NJ: Great Bay, Shallow tidal flats and Sand preference Time to completion ofLARVAE mm SL Little Egg Harbor; marsh creeks, metamorphosis temperature

NC: Pamlico Sound dependent. Increased(No pertinent and Cape Fear temperatures = shorterinformation for DE) estuaries, metamorphosis. Mortality

from < 2-4"C. No effect ofstarvation on mortality or timeto completion ofmetamorphosis at temperatures< 10C.,

JUVENILES - > 20 mm - NJ: Great Bay, Lower estuary: flats, NJ: found on muddy DE: > Y3C, all fish survived.- < 28 cm TL Little Egg Harbor; channels, salt marsh creeks, bottoms. NC: often greater NC: Feeding rate, growth rate

DE: Delaware and eelgrass beds. Possible abundances on sand or mixed and efficiencies increase withIndian Rivers, preference for creek mouths substrates. Scarcer on mud. increasing temperatures.Rehobeth Bays; (NJ) and inlets (NC). DE: Sand preference.' < 7-9'C = no positive growthNC: Pamlico Creeks are foraging habitat. Captured on sand and mud. rates (both DE, NC fish); 20-Sound, Cape Fear, DE: Attracted to macroalgae Substrate preference possibly 25'C = fastest growth rates.and adjacent because of the presence of overrides salinity preference. NC fish higher maximumestuaries, prey, but remain in nearby growth rates/growth

sand to avoid predation. efficiencies at 6-18"C than DEfish.'DE juveniles show greatertolerances for lowtemperatures than NC*juveniles. Mortality ofjuveniles depends more on rateof temperature decline than onfinal exposure temperatures.1

ADULTS ~> 28 cm TL Delaware Bay Captured from the shorelineto 25 m.

(No pertinentinformation for NJ,NC)

1 Laboratory studyD.O.: no pertinent information

ReferencesNew Jersey: Rountree and Able (1992asb. 1997), Szedlmayer et al. (1992). Keefe and Able (1993, 1994), Szedtmayer and Able (1993), Witting and Able (1993), Grover(1998)Delaware: Smith and Daiber (1977), Malloy and Targett (1991). Malloy and Targett (1994a,b). Timmons (1995)North Carolina: Deubler and White (1962), Williams and Deubler (1968b). Peters and Angelovic (1971), Powell and Schwartz (1977, 1979), Weinstein el al. (1980a,b),Powell (1982). Ross and Epperly (1985). Burke (1991), Burke et al. (1991, 1998). Malloy and Targen (1994a.b). Burke (1995). Hettler et al. (1997). Walsh et al. (1999)

Table 5. cont'd.

Life Stage Salinity Light Currents Prey Predators

TRANSFORMING Salinities found in Prefer burying NJ: Increased burial at Calanoid copepod Burying behaviorLARVAE lower estuaries during daylight.' flood tide;' however, NC: Temora longicornis -- determined by presence of

optimal for growth: Night active. possible surface or mid- indicates pelagic feeding. particular predator.'(No pertinent 10-30 ppt.; depth movement on Benthic feeding in late- NJ: 11-16 mm transforminginformation for DE) Increasing salinity = flood, settlement on ebb. stage metamorphs, prey larvae vulnerable to

increased body Position in water column includes polychaete predation by large sizeweight [Weinstein dependent on tidal stage, tentacles, harpactacoid range of shrimp C.el al. 80b: flounders utilize tidal copepods, polychaetes; septemvpinosa (- 11-50Distribution stream transport mm TL)'possibly influenced (behavioral componentmore by salinity suggested). Peak activitythan by substrate.] associated with ebb tide'.

JUVENILES More abundant in Visual predators, Selective tidal stream Smaller juveniles: DE: In caging experiments,higher salinities of feeding restricted to transport. Feeding, infauna (e.g., blue crabs were least able to18-35 ppt. Possible daylight, but NJ optimal environmental polychaetes). Larger prey on the flounder inpreference, but study (Rountree and conditions cause juveniles (- > 100 mm cages with sand bottomsinteractions with Able 97) shows movement. TL): fish, shrimps, crabs; only, but had an advantagesubstrate increased night-time DE: No pertinent often tied to abundance in capturing the flounder inpreferences. catches in marsh information, in environment. cages containingDE: Experimental creeks. macroalgae.1salinity variation DE: No pertinent NJ, NC: No pertinent(10-30 ppt) had no information, information.effect on feeding,growth or survival.'

ADULTS < 45 cm fed oninvertebrates, > 45 cm

(No pertinent TL ate more fish. Ininformation for NJ, order of % frequency ofNC) occurrence: shrimp (C.

septemspinosa),weakfish, mysids (N.americana), anchovies,squids, Atlanticsilversides, herrings,hermit crabs (P.longicarpus), isopods(0. praegusta).

Laboratory studyD.O.: no pertinent information

ReferencesNew Jersey: Rountree and Able (1992a.b. 1997). Szedlmayer et al. (1992), Keefe and Able (1993.1994), Szedlmayer and Able (1993). Witting and Able (1993), Grover(1998)Delaware: Smith and Daiber (1977), Malloy and Targett (1991), Malloy and Targett (1994a,b), Timmons (1995)North Carolina: Deubler and White (1962), Williams and Deubler (1968b), Peters and Angelovic (1971). Powell and Schwartz (1977, 1979), Weinstein et al. (1980a.b),Powell (1982). Ross and Epperly (1985), Burke (1991). Burke ei al (1991, 1998). Malloy and Targett (1994ab), Burke (1995), Hettler et al. (1997), Walsh et al. (1999)

Table 6. Summer flounder catch and status (weights in '000 mt, recruitment in millions, arithmetic means).

Year 1989 1990 1991 1992 1993 1994 1995 1996 Maxz Min2 Mean'

Commercial landings 8.1 4.2 6.2 7.6 5.7 6.6 7.0 5.8 17.1 4.2 9.7Commercial discards 0.7 1.2 1.1 0.7 0.8 0.9 0.3 0.5 1.2 0.3 0.8Recreational landings 1.4 2.3 3.6 3.2 3.5 4.1 2.5 4.7 12.7 1.4 5.4Recreational discards 0.A 0.6 1.1 0.9 1.8 1.4 1.8 1.6 1.8 0.1 1.1Catch used in assessment 10.4 8.3 12.0 12.3 11.9 13.0 9.5 10.5 27.0 8.3 16.6

Spawning stock biomassr 5.2 7.5 5.8 7.3 9.3 12.4 17.3 17.4 18.9 5.2 12.4

]At the peak of the spawning season (i.e., November 1). 2Over period 1982-1996.

Figure 1. The summer flounder, Paralichthys dentatus (from Goode 1884).

760 740 720 700 680 660

• P resent :i:,::•.:... ::=:

420

Number Fofutainde amld:251

Fish Caught/station (excluding 0 catchies):Mean: 8 Min: 1 Max: 716

Length (cm):Mean: 34 Min: 4 Max: 82

Figure 2. Overall distribution of adult and juvenile summer flounder in NEFSC bottom trawl surveys in autumn (1963-1996), winter (I 964-I 997),ý spring (1968-1997), and summer (1964-1995) [see Reid et al. (1999) for details].

3401ý'-

Figure 3. Distribution and abundance of juvenile (< 28 cm TL) and adult (> 28 cm TL) summer flounder by season,collected during NEFSC bottom trawl surveys during autumn (1963-1996), winter (1964-1997), spring (1968-1997) andsummer (1 964-1995) [see Reid et al. (1999) for details].

I.

I

Figure 3. cont'd.

Adults: > 28cm TL

SPRING SUIVTVER

70-

65-

60-55-

50-

45-

40-

S35-uj -WU30

25-

20-

15-

10-

5-A

oi STATION'S N612598 CATCH-ES N-4534

75-70-65-60-55-

50-

~45-w 40-0° 35.

r0 30-25-

20-15-

10-5-

0 STA11Or' N=1 1* CATCHES N6745

Al llll--J i i J i i i i• i i i i J i i JJ i i i i i i iii i J i iI I

0

DEPTH (i)

0

DEPTH (m)

WINTERFA.L

70

65

60

56

50

45

t40

035

L30~

25.

2D

15.

10.

5.

o STA11T'S N6198M CATCHES N=1 1630

70

65

60

55

50

45

~40LLI035w 30a_

25

20

15

10

5

0

0 STA11ONS N64320 CATCH-ES N=9418

ImI I ,,4,m I1I1.1'.nI-IIII III

0 0 04 0

DEPTH (mn)DEPTH (m)

Figure 4. Seasonal abundance of adult summer flounder relative to water depth based on NEFSC bottom trawl surveys[ 1963-1997, all years combined; see Reid et al. (1999) for details]. Open bars represent the proportion of all stationssurveyed, while solid bars represent the proportion of the sum of all standardized catches (number/I 0 m2).

Summer Flounder Summer Flounderi .. Mass. Inshore Trawl Survey Mass. Inshore Trawl Survey

Autumn 1978 - 1996 Spring 197 8- 1996Adults (>=28cm) : Adults (>=28cm)

7 4.... ...... .. . ... :.:. .

I, " t. 5. to :5 to 'o . ...'..5 to. 1390 10 to 15 t ..... to t 25I

015 to20 025 to 5020 to 32 0 50 to 83

:.... .. ...

~~...........

A:ji F.

Figure 5. Distribution and abundance of adult summer flounder in Massachusetts coastal waters from shore out to 3miles during fall (typically September) and spring (typically May), based on bottom trawl surveys by the MassachusettsDivision of Marine Fisheries from 1978-1996 (Howe et al. 1997; Reid et al. 1999). Collections where no adults werecaught are shown as small x's.

Summer Flounder Adults (>= 28 cm)

Figure 6. Seasonal distribution and relative abundance of adult summer flounder collected in Narragansett Bay during1990-1996 Rhode Island Division of Fish and Wildlife bottom trawl surveys of Narragansett Bay. The numbers shownat each station are the average catch per tow rounded to one decimal place [see Reid et al. (1999) for details].

I "

Winter

V . I , . I I I . I . I I . I Ig .. I I I Iv I . . . . I25 27 29 31 33 35 37 39 4143 45 47 49 51

5-

4-

3-

2'

1

0-

53 55 57 59 61 63 65 67 69.

Spring

U I.&,1-i

25 272931 33 41 43 45 47 49 51 53 55 57 59 6163 65 67 69 7115"

12'

9-

6-

3'

0 -

I Summer

IIV -- . ....UE I& 1.P4M5 27 29 3133 3537 394143 4547 495153 5557 596163 656769 71

15-

12'Autumn

9"

6-

3'

025 27 29 31 33 35 37 39 41 43 45 47 49 5153 55 57 59 6163 65 67 69 71

Total Length (cm)

Figure 7. Seasonal length frequencies of summer flounder caught in Narragansett Bay during 1990-1996, from theRhode Island Division of Fish and Wildlife Narragansett Bay bottom trawl surveys of 1990-1996.

Adults (_ 28 cm)

30 [- E] Stations

20 U Catches Winter

10 20 30 40 50 60 70 80 90 100 110 120

25-

20- Spring

15

0 J 1 ' M=

10 20 30 40 50 60 70 80 90 100 110 120

.30 -

20- lSummer

10lOL

10 20 30 40 50 60 70 80 90 100 110 120

30'

Autumn20-

•.10

010 20 30 40 50 60 70 80 90 100 110 120

Bottom Depth (ft)

Figure 8. Seasonal abundance of adult summer flounder relative to bottom depth based on Rhode Island Division of Fishand Wildlife bottom trawl surveys of Narragansett Bay, 1990-1996. Open bars represent the proportion of all stationssurveyed, while solid bars represent the proportion of the sum of all catches.

Figure 9. Distribution and abundance of juvenile and adult summer flounder (12-76 cm TL) collected in Long IslandSound, based on the finfish surveys of the Connecticut Fisheries Division, 1984-:1994 (from Gottschall et al., in review).Circle diameter is proportional to the number of fish caught, and is scaled to the maximum catch (indicated by "max="or "max>"). Collections were made with a 14 m otter trawl at about 40 stations chosen by stratified random design.

105210-

n'=250Trows-lOG

Augustn =487

Tows-132

10-

I-

ITOlfh-i228n--52iMay

I

10

W14

10D

'ooo

10

I-

.h LilJunle

n--417w-133

Jutyn-170lwow8--63

Septembern-S8l

Tows- 290

Octeb•

n-652

Towms =288

Novembern-S9

TOWS-49

d u b11111111

1"

U.I

12 16 2D 24 28 32 36 40 44 48 52 5Q W0 64 68 72 7612 16 20 24 218 32 36 40 44 48 52 56 6D 64 68 72 76

Figure 10. Length frequency distribution (cm) of juvenile and adult summer flounder collected in Long Island Sound,based on the finfish surveys of the Connecticut Fisheries Division, 1984-1994 (from Gottschall et al., in review).

Summer FlounHudson-Raritan Es

Fall 1992-199Adult. (>28 cm

dertuary,

6

NEWYORK __

0) 'an

0

NEWJERSEY

Summer Flounder -Hudwn-Raritan Estuary

Sprin6 1992-1997"rAdults (>28 cm) y 0

Nofr"

0 low '99

*30.6o 69

NEWJYoRK

4usd

~I ~ S.

.* * * 11,,4

NEW *50

JERSEY 1 ~ \ S 201>29

Figure I1. Distribution and relative abundance of adult summer flounder collected in the Hudson-Raritan estuary duringHudson-Raritan trawl surveys in fall (October-December, 1992-1996), winter (January-March, 1992-1997), spring (Apriland June, 1992-1996), and summer (July and August, 1992-1996) [see Reid et al. (1999) for details].

Cd

I-

Newark BaySummer Flounder (Paralichthys dentatus)

40• May 1993

201 N=28 .

0 .. . . . 040-June 1993

20 , N = 10440-

4- "July 199320- " N = 80

401 Aug 19932011 N=40

40-1Sept 1993N = 10

40- Oct 1993204- Nt= 1 @,26.

40- Nov 199320 N=0

40-1

20:1 Dec 1993

40-

20- Jan 1994N=O

401] "Feb 199420 N=0

40-40

Mar 199420- N = 0

401. April 1994

20- • • N= 15

15 20 25 30 35 40 45 50 55Length (cm)

Figure 12. Length-frequency distributions of juvenile and adult summer flounder from Newark Bay, New Jersey.Collected using an 8.5 m otter trawl from May 1993-April 1994 (Wilk et al. 1997).

1987

ln=139l

0

0

'[ ... . ... . i~ijiiiji+• III•• ''+: ........ !•iz... .. ..... '•. .. ... ... . 'v :ii :

0

00

00

•`}•:•ii~!•ii7jii.•J+`+711•~i7J•:••i170 0i~•ii+i••• ; 0T? iT,;): •

++7+++++i ;++% +::++:++ +++++++g++++++++L +++++i@ 1++:i+'i+++:!+7++:• +? ++7+78: . +[+++++7 ++ + + '++ ++ ++ + +++++++++++++++++: .•0 ++:++:!•+•::!+8 :::5+::•'+•!:: : " : + : ::: ' ::08 ::

1990MARCH

@00:0

00

000000 00

0. o !i!!!•.. o !i

0

o7:::f::! ,p 0 +

I

0

@00 0

00

0000 0 0 e0

020 E

0,

0"NUMBER

OF~ FISH0 SYMBOL I TOW

0 0

6-10* 11-20

0~ 21-5051-100

Figure 13. Distribution and abundance of juvenile and adult summer flounder in Pamlico Sound, North Carolina andadjacent estuaries during years of high (1987) and low (1990) abundance. Collections were made by Mongoose trawl atstations chosen by stratified random design. Data based on North Carolina Division of Marine Fisheries trawl surveys,1987-1991. Adapted from Able and Kaiser (1994).

1990SEPTEMER

*~ .... ........

* o0

Figure 13. cont'd.

Summer flounder 1 Summer flounder(Paralichthys dentatus) 44 (Paralichthys dentatus)

Eggs MARMAP Eggs 4MARMAP Ichthyoplamnkton Surveys V AMPIchthyoplankton Surveys

43- 61-cm Bongo Net; 0.505-mm mesh - '61-cm Bongo Net; 0.505-mmm

1978 to 1907 Z;, January, 1978 to 1987

(Sep. Out, Nov. Dee. Jan. Ape May) hNumber of loss = 433. with eggs = 4

42 Nuwhorofiosu, witthoegggp389 "Y 42- Monthly Meon Density =002Eggs/lOwn'

41 \ "•" 41-

40- 40-i

17-, '7- _ 3

36 00o9 36- 0

35r - -- i 35 )2.4to -

76 75 74 73 72 71 70 69 68 67 66 65 76 75 74 73 72 71 70 69 68 67 6

Summer flounder Summer flounder(Paralichthys dentatus) (Paralichthys dentatus)(Pa Eggs Eggs

MARMAP lchthyoplanklon Surveys e" MARMAP Ichthyoplankton Surveys .

43- 61-cm Bongo Net; 0.505-mm mesh . - 3- 61-cm Bongo Net; 0.505-mm mesh

April, 1978 to 1987 " V V May, 1978 to 1987Numbero(lowss= 1020. witheggs= I II Nomceolos= 1065. witeggs=4

42- Monthly Moan 13-ity =0.023 E 42- Moathly Mean Density0.0Es

4 l .Non i Non

I040- t

39- 39- 1 ' a

38- 5 38-

37- o: tot0 37t 9

3 16to2

76 75 74 73 7'2 7'1 7) 69 60 67 66 65 76 75 74 73 72 71 70 69 66 67 6

Figure 14. Distribution and abundance of summer flounder eggs collected during NEFSC MARMAP offshoreichthyoplankton surveys from Cape Sable to Cape Hatteras during 1978-1987 [see Reid et al. (1999) for details].

Page. 59

45-

I Summer flounder(Paralichthys dentatus)

EggsMARMAP tchthyoplankton Surveys

43- 61-cm Bongo Net: 0.505-mm meshSeptember, 1978 to 1997

Number o.f lows = 747. with eggs = 24),

"Mthly MessnrIw.ity = I.56Eggs/lttn'

39-1

37-None

* I t t 10

S(Ito <-100

0 IM lio 116

36"'

35-74 73 72 71 70 69 69 67 66

45"

44

43-

Summer flounder(Paralichthys dentatus)

EggsMARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0,505-mm meshNovember. 1978 o997

Numher f loews = 915. with eggs = 1 V6

42-1 Monthly Mean Demily = 5.660 Eggs/l00u

41-

40-

37-1

SNo~ne

•I ':<100 10lo <100)

SIM) lo 279

36"1

74 73 72 ' 71 70) 69 66 67 66 65

Figure 14. cont'd.

w

SOUTHERN NEW ENGLANDLL 100.it.

0:I..Ju) 100IL0

04E= 100 ,' NEW JERSEY

0-,

100.ILI

0

W 100 DELMARVA PENINSULA

z 0- NS

w 100

100 VIRGINIA CAPESI TO CAPE HATTERAS

0: NS

100.

JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN

Figure 15. Monthly abundance of summer flounder eggs by region from NEFSC MARMAP offshore ichthyoplanktonsurveys from Cape Sable to Cape Hatteras during 1979-1981, 1984, and 1985 [see Reid etaaL (1999) for details]. NS =no samples. Adapted from Able and Kaiser (1994).

Summer Flounder Eggs

Q)

1008o6040

20

05040

3020

10

035302520151050

6050403020100

5040

30

20

100

1009020

10

08070603020

10

0

September Stations

Egg Catch

OctoberLit01November

~ Ij ~December

I

Bottom Depth (m), Interval Midpoint

Figure 16. Abundance of summer flounder eggs relative to water depth based on NEFSC MARMAP offshoreichthyoplankton surveys [1978-1987, all years combined; see Reid et al. (1999) for details]. Open bars represent theproportion of all stations surveyed, while solid bars represent the proportion of the sum of all standardized catches(number/10 M 2

).

I I I f I I I I45-:- - 1 1 1 1 1 L

Summer flounder(Paralichthy's dentatus)

Larvae

MARMAP Ichthyoplankton Survt6 1-cm Bongo Net; 0.505-mm me

43- 1977 to 1987

(Sop, O, No, Dee, Jn. Feh, Mar, Ap, M

Numbhcr of 1ows = 9459. with larvae

42-

40 4

eys*

sh

.y)

Lr-c)I 10ns

. I toolo

* 16101-(l

0 fOnlo 159

76 75 .74 73 72 71 70 69 68 67 66 65

45- -- L - t J - -___


44- Larvae

MARMAP lchthyoplankton surveys MARMAP lchthyoplankton Surveys61-cm Bongo Net: 0.505-mm mesh 4: , •\-. j 61-cm Bongo Net; 0.505-mm mesh

43- February, 1977 to 1987 " "• March, 1977 to 1987 m

Monthly Mean Density = 0.31 Lurvun/I0.', >~- Monthly Mean Denily =0.19 Luesuedl~ns5

4-Nttmhn ofltos=6866 sitill larve-24 42 Nuetnheoftow-10l3l. wills 1uru 19

39- - 439-

36- l 36-

35 - 35

76 75 74 73 72 71 7() 4, 6'8 6,7 6'6 65 76 75 74 73 72 71 7'0 69 64 67 6

Figure 17. Distribution and abundance of summer flounder larvae collected during NEFSC MARMAP offshore

ichthyoplankton surveys from Cape Sable to Cape Hatteras during 1977-1987 [see Reid et al. (1999) for details].

45-! . ... J _


44- ýLarvae

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh43 April, 1977 to 1987

Monthly Moon D.n.ily= 0.I I L -v ae./10 m

Nmnher of tows, = 1281. with larvae = 23 %

42-

41- " • N

40

39-

3.1'ýrv

None* toolS

* 1Sto 25

76 75 74 73 72 71 70 69 68 67

45-

44-

4 3 -

42-

41-

40-


LarvaeMARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm meshSeptember, 1977 to 1987

Monthly Moan D enity = 0.14 Larvwe/l()mh ,

45-

44-

43-

42-


Larvae

MARMAP Ichthyoplankton Surveys61-cm Bongo Net; 0.505-mm mesh

October, 1977 to 1987Monthly Moan Derity = 2,96 L arvae1ClnlNumboerof tow.% (47, with larvaec= 47Number of tows =774, with larvae = 8

39-

38-

37-1

74 7L arv e / 10 m

74 73 72 7'1 7(5 619 69 6'7 66 65

L-ra/10m

None

0 I to<10

S100Ito 121

36-[

74 73 72 71 70 69

Figure 17. cont'd. .

45_

Su(Para

44.

MARMAF

43- 61-cm Bo

Nov

Monthly Me1

412- Number of t

42-

40-

39-[ I

36- l

35- ,

inmer flounder'lichthys dentatus)

LarvaePIchthyoplanklon Surveys

ngo Net; 0.505-mm mesh'ember, 1977 to 197 --an Densily = 6.15 Lurvacl10mn Ytows =1031, w~ith larvae= 195

: None* I =o <0

* l01o<113

*i{ tmt159

76 75 73 72 71 7)1 69 6 67

Figure 17. cont'd.

I~l0 SOUTHERN NEW ENGLAND

c. 100'

0C14E NEW JERSEY

0 100

-I OCC 100.

IL0 DELMARVA PENINSULAcc 100.

zz,< 100-

,U

VIRGINIA CAPESTO CAPE HA1TERAS

o- NS -

1O00

JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN

Figure 18. Monthly abundance of summer flounder larvae by region from NEFSC MARMAP offshore ichthyoplanktonsurveys from Cape Sable to Cape Hatteras during 1979-81, 1984, and 1985 [see Reid et al. (1999) for details]. NS = nosamples. Adapted from Able and Kaiser (1994).

Summer Flounder Larvae

60

40

20

0

40

20

0

40

20

0

September Statios1 Catch

,•~ ~~ 9, 9, 9,• • • • •- - •. • - • ,

40 December20 ,

40 - January

~20 E

6040 February20 -] • • .[ ••[ , . . . . .20I~60 -March40o620Ij20 _ ¶ 9A-1 ' - - -1 -- 1

60 April40

20

.

40 May

Bottom Depth (m), Interval Midpoint

Figure 19. Abundance of summer flounder larvae relative to water depth based on NEFSC MARMAP offshoreichthyoplankton surveys [1977-1987, all years combined; see Reid et al. (1999) for details]. Open bars represent theproportion of all stations surveyed, while solid bars represent the proportion of the sum of all standardized catches(number/lO0 M

2).

Pre-transformation F - F G

H- H I

Figure 20. Classification of the transformation stages of summer flounder based on degree of eye migration [adaptedfrom Keefe and Able (1993) and Able and Kaiser (1994)]. The right and left eyes are bilateral and symmetrical in pre-transformation individuals. At the first stage of transformation, F -, the eyes are bilateral but asymmetrical with the righteye just dorsal to the left eye. By stage G, the right eye is visible from the left side of the fish. Stage H - differs from Gin that the cornea of the eye is visible from the left side of the fish. At Stage H, the right eye has reached the dorsalmidline. By Stage H +, the right eye has reached the left side of the head but has not yet reached its final resting place.At Stage I, the eye is set in the socket and the dorsal canal is closed.

2Q

107

Creek

* PitaEM LachicotteEM BeresfordEl Inlet

NOVEMBER 80n=O

40

APRILn = 143

r%V •.1

DECEMBERn=O

MAYn=31

u)

U-

0M

z

20

10

JANUARY 20n =25

10.

JUNEn = 87

I~~

16

8

8

4

0 "-"'-,

0 FEBRUARY;0 L n =245

0

0

MARCH0n = 134

0o

n-W =•a . . . ..

V.-

20

10

0

20

10

010

JULYn=1

AUGUST.n=0

10 30 50 70 90 110 130 150 30 50 70 90 110 130 150

TOTAL LENGTH (mm)

Figure 2 1. Length frequency distributions for transforming larval and juvenile summer flounder collected during 1986-1987 from estuarine marsh creeks in Charleston Harbor, South Carolina, using a rotenone/block net method (Wenner etat. 1990a). Adapted from Able and Kaiser (1994).

Summer Flounder Summer FlounderMass. Inshore Trawl Survey Mass. Inshore Trawl Survey

Autumn 1978 - 1996 Spring 1978 - 1996Juveniles (<28cm) Juveniles (<28cm)• .:. ::'::..... ......

Numberrrow NumberTow

I to 2 .to0 2 to 3 * 2 to 3

* 3 to4 3 to 49 4 to 50 t

5 to 6 5 t06

VS

.. .....

. .. .......

.. . .. . .

Figure 22. Distribution and abundance of juvenile summer flounder in Massachusetts coastal waters from shore out to 3miles during fall (typically September) and spring (typically May), based on bottom trawl surveys by the MassachusettsDivision of Marine Fisheries from 1978-1996 (Howe et al. 1997; Reid et al. 1999). Collections where no juveniles werecaught are shown as small x's.

Juveniles: <28'cm TL

70-65-60-55-50O

45-

2o 440-

15-

10-

5-

O SrAllT's N6713M CATCHES W-302

70-

65-60-55-50-45-

•40-wc)35-Crw 30-

25-

15-10-5-

o STAMtt'S W-84

* CATCHES N=44

DEP'H (M)o O 0 0 0

DEPTH (m)

N " W 8

FaLL

70-65-6D055-

50-45-

40-w035-w 3D-IL

25-

15-10-5-

o STAT1KS Nr&* CATCHES N-402

70-

65-60-

55-50-45-

I3-Z 40-

035-

20-

15-10-5-

O STAT1CI\IS W-M

* CATCHES N6-3

V IL.,,,0

IIPTH (mn)0 0 0 0 0 0 0 0 0

EEPTH (Mn)

Figure 23. Seasonal abundance of juvenile summer flounder relative to water depth based on NEFSC bottom trawlsurveys [ 1963-1997, all years combined; see Reid et al. (1999) for details]. Open bars represent the proportion of allstations surveyed, while solid bars represent the proportion of the sum of all standardized catches (number/10 M2

).

)"NEWSummer Flounder R YORK

Hudson-Ruritan Estuay ,Fall 1992-1996 - -

Juveniles (< 28 cm) o

State, a

NEW * : 2"t2HERSEY. 0 .6

Summer FlounderHudson-Raritan Estuary , "

Winter 1992-1997 fJuveniles (< 28 cm)j

SM.)

• .:.N'W

NEWJERSEY

5'.9o

It StoY*0 Oto910E t.6

Figure 24. Distribution and relative abundance of juvenile summer flounder collected in the Hudson-Raritan estuaryduring Hudson-Raritan trawl surveys in fall (October-December, 1992-1996), winter (January-March, 1992-1997),spring (April and June, 1992-1996), and summer (July and August, 1992-1996). [see Reid et al. (1999) for details].

Summer Flounder, 1995

NUMBER CAUGHT: 0=1 o9 ED= 10to 99 0 = 100 o 999 0 = >. 1.000

Figure 25. Monthly distribution of summer flounder in the main stem of Chesapeake Bay and in the major Virginiatributaries (from north to south: Rappahannock, York, James Rivers) from January-December 1995. Density values arethe total number of individuals caught in a 9.1 m semi-balloon otter trawl with 38 mm mesh and 6.4 mm codend.Adapted from Geer and Austin (1996).

Summer Flounder, 1995

C

L NUMBER CAUGHT: (D= 1 tog D= 10io 99 ( = 100 to 999 S = . 1.000]

Figure 25. cont'd.

1.71

0.9 .

2.0.

1.0 A

1.4

0.07- ' 1 •

3.0"-

01I IF * Ir I

1.5-

4.01

2.0]

001 t, . ?4'1k~ A AR fl1,

001I iiiw.rA A I -/

00

0.0 A I i

/iA A5.0.

, .I r , ,

1.5

0.0 1 14 IA

0.0

75.

0.0 I I !0.0-

0.0 . . • • ^

0 '00 200 300 400 500 600LENGTH (--,m)

JANUARY 950109 - 950113NO. CGHT. - 19 MEAN SIZE 199.1NO. MEAS. - 19 S E. SIZE - 9.1NO. HAULS - 40 MIN. SIZE - 128CAT./HAUL - 0.5 MAX. SIZE - 325

FEBRUARY 950201 - 950216NO. CGHT. - . 42 MEAN SIZE - 187.4NO. MFS. 4Z S.E. SIZE - 7.3NO. HAULS - 73 MIN. SIZE - 14CAT,/HAUL - 0.6 MAX. SIZE - 375

MARCH 950301 - 950313NO. CGHT. - 23 MEAN SIZE - 194.2NO. MEAS. - 23- S.E. SIZE - 6.4NO. HAULS - 40 MIN. SIZE - 139CAT./HAUL - 0.6 MAX. SIZE - 286

APRIL 950405 - 950418NO. CGHT. - 105 MEAN SIZE - 225NO. MEAS. - 105 S.E. SIZE - 5.6NO. HAULS - 73 MIN. SIZE - 146CAT./HAUL - 1.4 MAX. SIZE - 457

MAY 950503 - 950511NO. CGHT. - 176 MEAN SIZE 2- 31.1NO. MEAS. - 176 S.E. SIZE - 5NO. HAULS 79 MIN. SIZE - 53CAT./HAUL - 2.2 MAX. SIZE - 465

JUNE 950601 - 950614NO. CGHT. - 165 MEAN SIZE - 200.8NO. MEAS. 165 S.E. SIZE - 6.6NO. HAULS 88 MIN. SIZE - 68CAT,/HAUL - 1.9 MAX. SIZE - 500

JULY 950705 - 950724NO. CGHT. - 181 MEAN SIZE - 208NO. MEAS. I- a 1 S.. SIZE - 5.8NO. HAULS - 88 MIN. SIZE - 106CAT./HAUL - 2.1 MAX. SIZE -. 545

AUGUST 950801 - 950810NO. CGHT. 195 MEAN SIZE - 237.7NO. MEAS. - 195 S.E. SIZE - 4.7NO. HAULS - . 86 MIN. SIZE - 55CAT./HAUL - 2.2 MAX. SIZE 557

SEPTEMBER 950905 - 950920NO. CGHT. 210 MEAN SIZE - 241.4NO. MEAS. - 210 S.E. SIZE - 3.5NO. HAULS - 105 MIN. SIZE - 55CAT./HAUL - 2 MAX. SIZE - 504

OCTOBER .951002 - 951018NO. CGHT. 224 MEAN SIZE - 269.2NO. MEAS. 224 S.E. SIZE - 3.3NO. HAULS - 105 MIN. SIZE - 184CAT./HAUL - 2.1 MAX. SIZE 501

NOVEMBER 951110 - 951133NO. CGHT. 170 MEAN SIZE - 292.2NO. MEAS. 170 S.E. SIZE - 4.1NO. HAULS - 99 MIN. SIZE - 189CAT,/HAUL - 1.7 MAX. SIZE - 464

DECEMBER 951201 - 951213NO. COGHT. 16 MEAN SIZE - 281.9NO. MEAS. 61 S.E. SIZE 23.1NO. HAULS - 102 MIN. SIZE 37CAT./HAUL - 0.2 MAX. SIZE - 365

JAN - DEC 950109 - 951213NO. CGHT. - 1526 MEAN SIZE - 237.3NO. MEAS. - 1526 S.E. SIZE - 1.8NO. HAULS - 960 MIN. SIZE 14CAT./HAUL - 1.6 MAX. SIZE 557

Figure 26. Monthly length frequency summary for summer flounder in the main stem of Chesapeake Bay and the majorVirginia tributaries (Rappahannock, York, James Rivers) from January-December 1995. The y-axis represents the total

number caught for each size class, in mm. The bottom plot is a summary of all fish for the entire year. Adapted fromGeer and Austin (1996).

Summer Flounder Eggs

30 September E Stations

20 Egg Catch

0 _ _ _ _L__ _ _ _in_ _ _ _

40

30 October20.

10

0

20 - November

10 - _!0 .[ . . .I••, , . a ý9 -60

'40 December5 30

S20

610 ' JL 'i i

40 - January3020100 1i

90 April3020

40

30 - May20 j

o~ ,, . .. n ...

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Water Column Temperature (0-200m, C)

Figure 27. Abundance of summer flounder eggs relative to water column temperature (to a maximum of 200 m) basedon NEFSC MARMAP offshore ichthyoplankton surveys [1978-1987, all years combined; see Reid et al. (1999) fordetails]. Open bars represent the proportion of all stations surveyed, while solid bars represent the proportion of the sumof all standardized catches (number/10 mi2 ).

Summer Flounder Larvae

40 -

30

20 -

10 -o4

30

20

10

September Stations

tJ.i", P .... Catch

October j23°0o November20

40

30 - December20

30

H0 January

Lii JJ2u~.U

30 May20 I I10

0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

Water-Column Temperature (0-200m, C)

Figure 28. Abundance of summer flounder larvae relative to water column temperature (to a maximum of 200 m) basedon NEFSC MARMAP offshore ichthyoplankton surveys [ 1977-1987, all years combined; see Reid et al. (1999) fordetails]. Open bars represent the proportion of all stations surveyed, while solid bars represent the proportion of the sumof all standardized catches (number/l10 M2

).

Juveniles: < 28 cm TL

SPIING

70-

65-

60-

55-50-

•55.45-

Q 35-

10.

5-

10.

o STAIIC'S N=59D

I CA ES N=-2590 STATK'S N=82

U CATC-ES W-434

H00wr0W

n JLi.,ML4 I P4 .. .. ... ....-I4

0 2 4 6 8 10121416182D2224 262B0

E1M TBPVrEAUFE (Q

FALL

0 2 4 6 8 10 12 14 16 18 2 22 24 26 29 30

BOMTvl TBVPERA11FE (C

WINTER

70,

6560.5550-45.

~40035wI 30,

252D15,

10*5.

O STAGT'NS N=680

M CATCHES N=3540

70

65

65

55

5D

45

Z 4 D

w30

25

2D

15

10

5

0

O STA'11ON N6213

M CATCHES N62760

024i 1 1 1 1 .1 1 . . . . . . . . . . . . ' 'i1 i

6 8 1012141618202224262B30

6o01CM TBVPEPURA1E (C0 2 4 6 8 10 12 14 16 182D22242623D

60"1CM TEMPERAR•E (Q

Figure 29. Seasonal abundance of juvenile summer flounder relative to bottom water temperature based on NEFSCbottom trawl surveys [1963-1997, all years combined; see Reid et al. (1999) for details]. Open bars represent theproportion of all stations surveyed, while solid bars represent the proportion of the sum of all standardized catches(number/lO0 M2

).

Summer HoMass. Inshore Tra

Juveniles

30'

20'

10" Ju~lA

25

Spring 20-

15

10

5"

under E[ Staiowl Surveys Catches

Adults

Spring

SHn lrlJlk

U)

I 3 5 7 9 II 13 15 17 19 21 2-3

Bottom Temperature (C)

40-Autumn

30'

20"

10"

0~1 3 5 7 9 11 13 15 17 19 21 23


50"

40- Spring

-30-

20"

10"

0 p .- , ,--

Bottom Depth (m)

80 -

Autumn60"

40'

2()- n po

3 5 7 9 II 13 15 17 19 21 23

Bo tto m Temperature (C)

30-

20-

10-

0-

50"

40'

30-

20"

10"

Autumn

_onAfl nnIIIIl3 5 7 9 II 13 15 17 19 21 23


Spring

I~iL-nnn.ý,

b 2tlt4gg.gggW~-

I mF. F= -

Bottom Depth (m)

i I Autumn

40'

30'

20"

10"

I" n n r-1 , ,I m m

Bottom Depth (m) Bottom Depth (m)

Figure 30. Abundance of juvenile and adult summer flounder relative to bottom water temperature and depth based on,Massachusetts inshore trawl surveys (spring and autumn 1978-1996, all years combined). Open bars represent theproportion of all stations surveyed, while solid bars represent the proportion of the sum of all standardized catches(number/10 mi2 ).

80

60

40

20

0

80

60

40

20

CreekI Pita

J LachicotteJ Beresford

Inlet HI.

ANUARYn = 18

EBRUARYn = 245

4 ! (

FE

I

0

z

0! -- _ £4"t

30 MARCH50 n = 134

40

30. APRIL

n =14350.40oR20

80' MAY

60 n =31

40'

>0

20-830 JUNE60 n=6

10-

Ž01

801

60-

40

20

JULYn =1

N ~

SALI NIT .. .b

SALINITY (ppt)

Figure 31. Abundance of juvenile summer flounder relative to salinity in four Charleston Harbor, South Carolina marshcreeks during 1987. Fish were collected using a rotenone/block net method [data based on Wenner et al. (1990a)].Adapted from Able and Kaiser (1994).

oi=13 o=29 n=17 M'=6

V

U

'a

iIL-i. 11-14 Iiz-Iu 17-18 21- 2

mm group ( L")

co'pepods tenta~cls ficopepodsPolychaetes Mrsids I~1111Amphiixsds

Z -1t 7-7

/7 7/ 7 >/,~/,

~2'

FTT7 (~ btnr~i ~ Triv '±br~tefl,

.1I1~A: ip h ipcLs S'rm YF 4 and caiD

Figure 32. Relative importance of each diet item (percentage of total number multiplied by the frequency of occurrence)to: (top) different length groups of summer flounder during the immigration period, January-March 1988, in the Newportand North Rivers, North Carolina; and (bottom) to 20-60 mm SL summer flounder following segregation from southernflounder in April-June 0988 in the Newport and North Rivers, North Carolina. Relative importance values are presentedas the percentage of the sum of all values for (top) each 2 mm length group and for (bottom) each species. Adapted fromBurke (1995).

100"

90-

80-

70-

60-

50-

40-

80/106 33/45

OTHERS OTHERS

CRABS CRABS1 (3) \

M SHR IMPAMPHI- (3)PODS

(19) MYSIDSr (46)

ISOPODS(2)

95/120 92/138OTHERS

CRABS (7) OTHERS

SHR IMP(5)

CRABSISOPODS (2)

(5)

92/179 42/150OTHERS OTHERSCRABS

(6 ), AMPHI-PODS

SHRIMP (2)

(9)

MYS IDS(82)

MYSIDS(76)

AMPHI-POD)S (5)

ISOPODS(2)

MYSIDS(72)

MYSIDS(73)

46/65OTHERS 1

CRABS/(4)

SHRIMP(13)

AMPHI-PODS

(6)

MYSIDS(83)

39/48

CRABS(3)

MYSIDS(74)

MYSIDS(60)

FISH(46)

FISH(54)

30- FISH(36)FISH

(37)FISH(24)

FISH(44)

FISH(17)

20-

FISH(37)

10-

SUMMER SOUTHERN

FLOUNDER FLOUNDER

SUMMER

SUMMER SOUTHERN

FLOUNDER FLOUNDER

WINTER

SUMMER SOUTHERNFLOUNDER FLOUNDER

FALL

SUMMER SOUTHERN

FLOUNDER FLOUNDER

SPRING

Figure 33. Percentage of volume and (in parentheses) percentage of occurrence of food items occurring in the seasonaldiet of young (100-200 mm TL) summer and southern flounder from the Neuse River and Pamlico Sound, NorthCarolina, Numbers above each bar graph indicate the number of stomachs with food/the total number of stomachsexamined. Adapted from Powell and Schwartz (1979).

Adults: _> 28 cm TL

SPRNG

50-

45-

40-

[I STATIKNS NOW~S

M CATCHES N=4Ofl4

0 STA11TKN N61050 CATCHES N6727

35+

ý 30-025-

•2D-

15-

10-

5-

wiii(wc

rLIII-

I . I . I . I . I

024 6 8 10 12 14 16 1820222422B30

BOTTOM nBPEPAn.FE (q

0 2 4 6 8 10 12 14 16 182D22 24 22B3

6011M TEIVERA~TFE (C)

FA-L WINTE:50-

45-

40-

35-

o0-5

W1) 5-

10-

5-

o STA11CNS N616725 CATCHES N610093

5D0

.45-

40-

35-

-3D-Zo25-2D-

15-

10-

5-

0 STATI1NS=421

* CATCHES N=9D14

11111O-ui .. . . . iIi~

0 2 4 6 8 10 1214 1618 2D222425 2B30

BO11DM TVEvPEATUFE (C)

0 2 4 6 8 10121416182D2224282B30

Bo01OM TEMPERAT1JE (C)

Figure 34. Seasonal abundance of adult summer flounder relative to bottom water temperature based on NEFSC bottomtrawl surveys [1963-1997, all years combined; see Reid et al. (1999) for details]. Open bars represent the proportion ofall stations surveyed, while solid bars represent the proportion of the sum of all standardized catches (number/10 M2

).

20"

16'

12

8

.4-]

Adults (Ž> 28 cm)El Stations

E Catches

Winter

RHHn_- 1 3 5 7 9 11 13 15 17 19 21 23 25 27

50-

40- Spring

30"

20"-o _n Hn nt n o-t!

-1 1 3 5 7 9 1 13 15 17 19 21 23 25 27

20'

16- Summer

12'

8"

4'

0-_-1 1 3 5 7 9 11 13 15 17 19 21 23 25 27

40-

30'Autumn

20-

10-

0 -1 1 3 5 7 9 11 13 15 17 19 21 23 25 27


Figure 35. Seasonal abundance of adult summer flounder relative to mean bottom water temperature based on RhodeIsland Division of Fish and Wildlife bottom trawl surveys of Narragansett Bay, 1990-1996 [see Reid etal. (1999) fordetails]. Open bars represent the proportion of all stations surveyed, while solid bars represent the proportion of the sumof all catches.

1973-1980(n = 243)

Other 3.4%

Crustacea

Other 17.9%

Ammodytes sp. 19.8%

Unknown Fish 62.3%

Unknown Cephalopoda 61.8%Other 3.4%

Nematoda 2 Mollusca 34

"•,Crustacea 110Fish 16 :;

Other 11

Other Crustacea 29

Ovalipes ocellatus 7Cancer irroratus 13

Crangon septemspinosa 17

Neomysis americana 44

Figure 36. Abundance (percent occurrence) of the major prey items in the diet of summer flounder collected duringNEFSC bottom trawl surveys from 1973-1980 and 1981-1990, focusing on fish, crustaceans, and mollusks. Thecategory "animal remains" refers to unidentifiable animal matter. Methods for sampling, processing, and analysis ofsamples differed between the time periods [see Reid et al. (1999) for details].

1981-1990(n = 469)

Animal Remains 6.7%

Crustacea 28.0°/0

Polychaeta 0.4%

Mollusca 11.2%Ctenophora 0.2%

Butterfish 5.2%Sand Lances 10.5%Cods 3.8%

Anchovies 17.4%'

Other Families 13.2%

Unknown Fish 49.8%

Fish 53.5%Other Mollusca 3.3%

Loligo sp. 40.0%

Unknown Cephalopoda 56.7%

Animal Remains 6.:

Mollusca 11.2%

Other Crustacea 16.0%

Amphipods 13.3%

Crabs 43.3%

Shrimps 27.3%

Fish

Figure 36. cont'd.

Georges Bank - Middle Atlantic

20

18

0.0.

C,,

0

16-

14

12

10

8

6-

I////

0

0.4-'

C-)

C

a)

L..

'.7V

4

2 4-,-1,960 1965 1970 1975 1980 1985 1990 1995

,+ 02000

Year

-Commercial landings (mt)----- Spring survey index (kg)

- _ Smoothed survey index (kg)- Spawning stock biomass (mt)

Figure 37. Commercial landings, NEFSC survey indices, and stock biomass for summer flounder on Georges Bank andin the Mid-Atlantic region.

76' 740 72' 700 68. 660 760 740 720 70' 680 660

Numbero Fish Number olfRsh .

0-0 0-0 W E

S10- 99 " 10-9 9

* 100-999 . .0 100 999

42o. - C. j q ' . 42 -. , I .-

e• / " : " *•" v *-•' - -/'4.,... CT-

38* 3 80oý

Summer Flounder--Adults (>28cm) Summer Flounder--Adults (>28cm)

, Fall (1974 - 1978) Fall(1989- 1993)360 o y :i NEFSC Bottom Trawl Surveys 360 NEFSC Bottom Trawl Surveys

, Fish caught/station (excluding null stations): Rsh caught/station (exciuding null stations):z,0 Mean: 6 Min: 1 Max: 52 ' Mean: 4 MIn: 1 Max: 48

Length (cm): Length (am):Mean: 39 Min: 29 Max: 79 I Mean: 37 Min; 29 Max: 70

76' 74° 720 700 680 660 76° 740 720 700 680 66'

Number of Fish Number of Fish

1 0- 9 9 .,-

•10 99 . 10 -99 I NH

* 100 - 99'9' y ".-' .:.. 10 999

* 1000-90000b 0090; ' -42' _X1 "42o ;.. t oo o .•_,. .. -'• •• • • -................. . . . ..'. .'"

40o 40,oY>: :. 1

- , . ,. i

i~• ..4 ..... - '.-._. .... • . .-• ,: -

8* 38*

Summer Flounder-Aut)28m Srn (1989 1993)de~ D.~ Spring (1974.-1978) ~ ~ Summrin Flounder-Au (199 cm36-NEFSC Bottam Trawl Surveys 3*NEFSC Bottam Trawl Surveys

4Fish caughtlstatlon (exciuding nulstations):.ihcuh/tlo exldn ulsain)Mean: 5 Min: 1 Max: 153 JJ-Mean: 2 Min: 1 Max: 9

Length (cm): -. Length:(m

Mean: 41 Min: 29 Max: T7 Mean: 37 In: 29 Max: 72

34l--3401 I' I. J l .J A i L

Figure 38. Distribution and abundance of adult and juvenile summer flounder during a period of high abundance (1974-1978) and a period of low abundance (1989-1993) based on spring and fall NEFSC bottom trawl surveys [see Reid et al.( 1999) for details].

72o 700


34o0:Length (cm):Mean: 23 Min: 15 Max: 28

760 740 720

Number of Fish l !, .

0 - 0 ,

10 99

100. 999 NA

1000 .9000 -

700 680 660

ME' ~

MA

Cr i

~3/

Summer Flounder--Juveniles (-= 28 cm)Spring (1974 - 1978)NEFSC Bottom Trawl Surveys

Fish caught/statlon (excluding null stations):Mean: 7 Min: 1 Max: 76


j340 i_ - 7._1. ... .

Figure 38. cont'd.

summer flounder, life history and habitat characteristics

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