202

The Fish Fauna of Otsego Lake

John R. Foster+

Over the past 25 years, fish surveys have been conducted by a variety of workers at the Biological Field Station (BFS) (New, 1971; 1973; Harman et al., 1980; MacWatters, 1980; 1983) and by the NYSDEC. Unfortunately, some of the earlier BFS reports are qualitative and do not lend themselves to quantitative comparisons wi th more recent work. This report relies primarily on data collected by J. R. Foster and his students since 1988.

Otsego Lake can be conveniently divided into 4 major habitats: (1) warm, shallow, weedy areas which occur primarily at the north and south ends of the lake and in embayments; (2) rocky shoals, where steep drop-offs occur over most of the eastern and western shores; (3) epilimnetic waters which occur offshore; and (4) profundal offshore waters which occur in the deepest part of the lake basin.

Because different sampling techniques and gear must be used to examine the fish fauna of these maj or habitats, survey data on relative abundance, diversity, and faunal changes are open to interpretation. Further, catch per unit effort (cpue) and percent species composition will vary with time of year and among sample locations. Most of the data presented here were collected primarily from the end of May through September in the portion of Otsego Lake south of Point Florence.

THE INSHORE FISH FAUNA OF OTSEGO LAKE

Littoral waters were sampled utilizing a 4-foot Pennsylvania trap net with a 50' lead, a 25 x 5' (3/8" stretch mesh) shore seine and a 150 • x 8' (5/8" stretch mesh) haul seine. The haul seine sampled out to a depth of 5 feet. The haul seine and shore seine were more effective in sampling small fishes, particularly young­of-the-year, while the trap net captured more adult fish and those active at night.

During the summer months, the in-shore fish fauna of Otsego Lake contained 24 species in 8 families (Tables 1,2,3). Overall, the sunfish/bass family (Centrarchidae) dominated inshore waters. However, the alewife (Alosa pseudoharengus), which generally come

+BFS Visiting Researcher. Present address: Fisheries and Aquaculture, SUNY College of Agricul ture and Technology, Cobelskill, N.Y. 12043.

Susque- Black Rat Brook- Leather Trout Hayden Publ ic Shadow flyde Point Mean family Species hanna

Outlet Bird Bay

Cove wood Point

stocking Brook Mouth Mouth

Creek Mouth

Landing Brook Mouth

Bay Judith Catch

Herring Alewife .9 1.0 1.7 3.4 .6

Suckers White Sucker .5 .2 .8 .2 3.0 .7 .2

Minnows Carp .2 .5 .2 .1 Golden Shiner .5 .1 .3 .5 1.0 1.0 .3 Emerald Shiner .3 1.8 .2 Spottail Shiner .1 .9 .1 .1 Bluntnose Minnow 2.5 .6 .4 .3 2.2 1.5 .3 _7 Fathead Minnow .5 .1 .1 European Rudd .3 _0

Pickerel Chain Pickeral .8 .1 .3 .1

Topminnows Banded Ki 11 i fish 22.5 .9 .4 1.3 2.3

Catfish Brown Bullhead 1.0 .1 .5 .5 .2 Channel Catfish .1 .0

Sunfish/Bass Rock Bass .5 .3 .2 .3 .5 .2 Redbreast Sunfish 1 . 5 1.5 2.0 1.9 3.8 .5 .4 2.0 1.2 Pumpkinseed 1.0 1.5 18.8 1.7 1.8 .3 1.2 2.4 .7 3.5 3.0 Bluegill 17.6 .9 1.0 1.0 .5 1.9 Smallmouth Bass 1.0 .4 .4 .7 1.5 1.3 .9 .3 2.0 .8 Largemouth Bass .5 1.3 .7 .5 1.5 1.7 3.6 .7 1.0

Perch Tesselated Darter 3.0 2.0 3.0 .6 1.2 .5 .3 .3 .1 1.0 Yellow Perch 1.0 2.9 1.0 .7 .3 .6 2.0 .8

Site Mean 7.3 32.0 50.6 8.6 10.2 3.5 5.8 12.7 18.6 4.7 11.5

Table 1 . Inshore summer fish abundance measured in catch per unit effort utilizing paired shore seine haul seine catches. Sample locations follow a clockwise pattern around the lake, starting at the Susquehanna River,

No w

Family Species 1989 1990 1991 1992 1993 Mean (27 ) (33) (31) (35 ) (38 )

Herring Alewife .6 14.4 31. 2 14.4 10.5 14.2

Suckers White Sucker 1.3 .5 .2 .7 .1 .6 Creek Chubsucker .2 .5 .2 .7 .2 .4

Minnowc-; Carp .1 .2 .1 Golden Shiner 1.1 .9 .4 1.5 .9 1.0 Emerald Shiner .1 .0 .0 .0 European ](udd .1 .1 .1 .1

Pickerel Chain Pickpral .2 .1 .1 .1 .1 .1

Catfi~;h Brown Bu]lhpad 1.5 2.1 .1 .5 .3 .9 Tadpole Madtom .9 .2 .2

Sunfish/Bass Rock Bass 2.0 1.0 .8 2.6 8.1 2.9 !,pdbreast Sunfi~3h .2 .2 .3 .6 .2 .3 Pumpkinseed 7.1 2.7 3.1 9.1 4.2 5.2 Bluegill 6.8 3.8 2.9 4.9 .2 3.7 Largemouth Bass .5 .2 2.1 .2 .2 .6

Perch Yellow Perch 4.1 3.0 .5 1.7 .2 1.9

Yearly Mean Catch 25.8 29.7 42.0 38.1 25.5 32.2

Table 2 . Inshore summer fish abundance measured in catch per unit effort utilizing a 4' Pennsylvania trap net. Number of 24 hour sets are given in parenthesis,

N o ,J:>.

Family Species 1989 1990 1991 1992 1993 Mean (ll) (33 ) (26) (8 ) (6 )

Herring Alewife 4.8 1.0

Suckers White Sucker 4.7 1.0

Minnows Carp .2 .1 .2 .7 .2 Golden Shiner .6 .5 .2 Bluntnose Minnow .1 .0 .0 Fallfish .1 .1

Pickerel Chain Pickeral .4 .0 .5 .2

Catfish Brown Bullhead .8 .0 1.2 .4

Topminnows Banded Killifish .3 .4 .1

Sunfish/Bass Rock Bass 1.6 2.4 1.8 1.2 5.8 2.6

Redbreast Sunfish 2.0 2.6 2.8 2.4 3.3 2.6 Pumpkinseed 9.5 4.2 2.6 25.6 1.2 8.6 Bluegill 14.6 7.5 7.5 15.4 .2 9.0 Smallmouth Bass .7 .6 4.0 .6 .6 1.3 Largemouth Bass 2.7 .3 .9 1.0 .3 1.0

Perch Tesselated Darter 1.5 .3 Yellow Perch 3.7 .6 2.7 2.3 2.3 2.3

Mean Catch 42.0 18.3 27.3 51. 4 15.6 30.9

Table 3 . Inshore summer fish abundance measured in catch per unit effort utilizing a 150' haul seine. Sample size is given in parenthesis. \t-o

tv o 0'1

206

into inshore waters at night (Emery, 1973), currently appears to be the most abundant species and seems to have the most influence on the other fish populations.

High trap net catches relative to seine catches for alewives and chubsuckers indicate inshore movement at night, or, in the case of tadpole madtoms, increased nocturnal activity (MacWatters, 1983) .

Changes in Inshore Fish Populations

Alewives were first detected in Otsego Lake in 1988 (Foster, 1990). That year, the only specimen collected was found in a lake trout stomach. Trap net data (Table 2) indicate that in two years it became the dominant species in the lake (Foster and Gallup, 1991). The percent of alewife in trap net catches rose from 0% in 1988, to 2% in 1989, 48% in 1990, and peaked at 74% in 1991. Populations have since leveled off at 38% and 41% of catch in 1992 and 1993, respectively (Table 2) .

The combined catch of non-alewife species was negatively correlated to the alewife catch. In 1991, when alewife catch peaked at 31.2 fish per 24-hr set, the combined catch of all other species was lowest at 10.8 fish per set. The inshore populations of many species (e. g. golden shiner (Notemigonus erysoleueas) , whi te sucker (Ca tostomus eommersoni) , brown bullhead (Ietalurus nebulosus) , pumpkinseed (Lepomis gibbosus) , bluegill (L. maeroehirus) , and yellow perch (Perea flaveseens)) dropped as alewife increased. Following an alewife die-off in 1992 (documented by the presence of thousands of dead individuals following ice breakup) the populations of these species have rebounded.

The overall five year trend for pumpkinseed and bluegill indicated a decrease in their populations in inshore waters. Current conditions seem to favor pumpkinseed, as bluegill populations have dropped more drastically. Other species, such as emerald shiner (Notropis atherinoides) and bluntnose minnow (Pimephales nota tus) also showed a drop in inshore populations between 1989-1993.

In most cases, year-to-year fluctuations in seine catches followed a similar pattern as trap net catches, although seining captured a much higher percent of young-of-the-year and juveniles, whil.e the trap net captured a much higher percentage of adults (Tables 2,3). Most bass and sunfish showed large peaks in year class strength. For example, the 1992 haul seine catch of bluegill and pumpkinseed indicates a very good year class. Population changes in predators of small fishes, such as rock bass (Ambloplites rupestris) , largemouth bass (Mieropterus salmoides) ,

207

smallmouth bass (M. dolomieui) , yellow perch, and pickerel (Esox niger) did not follow the same pattern. This would indicate that other factors besides food supply are affecting tr"eir numbers. Rock bass was one of the few fish that had a larger inshore population in 1993 compared to 1989.

Changes in the occurrence and abundance of inshore fishes are cTvTiderlt ~rl cOlnparlsons of ~v1ac~'Jatters sur'v'ey's (t·1ac~·Jatters, 1983; MacWatters et al., 1981) and BFS surveys conducted between 1988 and 1995. Six species present in the late 70's, early 80's (fu~erican

eel (Anguilla rostrata), redfin pickerel (Esox americanus) , ITiargirled rnadtOITl (l'Joturus ilisig.rJis) , blackcf1ill srlinsr (l'Jctropis heterpdon) , rosyface shiner (N. rubellus) , and spot fin shiner (N. spiloterus) appea.c to be absent in Otseao Lake. vvhile most of tllese sp,ecies v-Jere relat-=-'Jel':i lJ.llCCITLffiOn ir~ ~98C, the ma:cgined mad.t~~l

was considered common and the rosyface shiner was considered a major forage species (MacWatters, 1983). r'urther, he (f'-1ac\fJatters ~t al.,1981) considered the spottail sn~ner l~. hudscnius) to be common, and this species is currently rare (Table 1).

In-Shore Fish Distribution

A survey of the inshore waters of Otsego Lake indicated that most species of sunfish and bass were widely distributed (Table 1). Species that occurred in two thirds or more of the sample sites included redbreast sunfish (L. auritus) (8 sites), pumpkinseed (10

~_ --J CLIIU.sites), smallmouth bass (9 sites), largemouth bass (8 sites),

tesselated darter (Etheostoma olmstedi) (9 sites). Most species with a very restricted distribution were in the minnow family: carp (Cyprinus carpio) (3 sites), emerald shiner (2 sites), spottail

It) ~..:+-~~\ ~ __ ...Jshiner (3 sites), fatrlead ITlillnC'w (P" -L;:)1..~c'melas) \L :::>...LLeo), allu

European rudd (Scardini us erythroph tha lmus) (1 site) . Further, c 1~1 a i 11 pic k ere 1 (3 s 1. t e :3), a rl d c 1-1 a rl (l e 1 C 3. t f i S 1-1 (I. D UIJ eta t: ~_1 5 :' ( 1

fish were generally 110'- evenly disr_ribuced throughout­~ / .

concentrations. For example, Rat Cove appears to be a maj or nurse :C~i area for pUHlp.K2-DSeed and b1 ue<} ~ II . Banded k2-l-:.- i:: ~5r

(Fundulus diaphanus) were concentrated in the emergent rushes of Blackbird Ba~i" BaGJed killifish and tesselated darter seem tc bs

---." "',11 ,-. '::-, 1""' '"- -,.- :"' +- ..:::::-. ,-.J ~,......, '-..--vJ.J.'--'cJ. .. '- ...... ..:Al.-'--''--1. ....l... ... J. ~~2 ~~sh8~2 ~;a~2~S 2~ Sc~t~2~:: ~~S2;8 L6~:2, ~~~~_2

emerald shiner, spottail shiner, fathead minnow, and alewife tended to dominate In the northern inshore Haters .white suckers -I-Jere

~ ~-., ,~ ,..-, --..., -- -.-'--=C~-:,~~2=~-::.'d~ed 2l--G~=-:j =__ 2,\\:~:-:g -.-.;a::er ...,-.- :3~~-e.~=::' =':'L~-:·-..:.~~--....::: .:::1...:. ... '-'1. .. .I.e.::: ........

lake's outlet at the Susquehanna River.

The critical factor determining species diversity and abundance in inshore waters is the denslty and Qlversity of aqua~~c

208

vegetation. The four areas having the highest macrophyte densities had the highest species diversity and fish density (Rat Cove, 15 species; Brookwood Point, 13 species; Shadow Brook, 15 species; and the Springfield Public Landing, 15 species). Shallow turbid areas, such as the mouth of Hayden Creek and Hyde Bay, with minimal inshore (eulittoral) vegetation had low species diversity and fish abundance. Low species diversity also occurred at Leatherstocking Creek mouth, which had a monostand of water lilies, and Blackbird Bay, which had a monostand of rushes.

In the absence of plants and cover, in-shore species diversity in Otsego Lake is low on both fine and course substrates. Open areas with substrates of cobbles and channery, such as Point Judith and Trout Brook, had relatively few species, as did open areas with finer substrates and few plants (upper Susquehanna River, Blackbird Bay, and Hyde Bay). Physically, the fine and coarse substrate areas were similar; however, they had few species in common. These localities probably have few resident fish, with the catch being primarily transients.

In 1980 (MacWatters et ai., 1981) a number of lotic species were present near the mouths of streams during the summer (common shiner (N. cornutus), blacknose dace (Rhinichthys atratuius), and creek chub). However, in surveys conducted between 1988 and 1995 these species were not collected from Otsego Lake. Alternatively, the emerald shiner was not taken in inshore waters in 1980 (MacWatters et ai., 1981), but was found in inshore waters in 1994. Thus, there were two major changes in fish distribution indicated by surveys of the early 1980s and more recent surveys; (1) an apparent movement of stream species, such as creek chub, longnose dace, blacknose dace, and common shiner out of stream mouths, and (2) movement of open water lake species, such as alewife, spottail shiner, and emerald shiner into stream mouths.

THE FISH FAUNA OF NEARSHORE WEED BEDS

The fish fauna of littoral waters having high densities of macrophyte growth was sampled with coarse mesh experimental gill nets (300' by 8'; 1.5, 2.0, 2.25.2.5,3.0,3.5 inch mesh) and trammel nets (300' by 8', 1" inner mesh, 12" outer mesh). Nets were set in Rat Cove and ran perpendicular to shore from 8 feet of water to approximately 25 feet. Virtually all fish captured in these nets were adults. The coarse twine used on the sampling nets were inef fecti ve on slender fish such as the alewife, and the smallest mesh sizes were too large to accurately sample small fish such as minnows.

With few exceptions (e.g. pickerel), warm-water fishes are generally most productive in waters that exceed 20° C. They are

209

characterized as spawning in the late spring or summer and live throughout the year in shallow or surface waters. Warm-water fish, including such major groups as the pickerels (Esocidae), minnows (Cyprinidae), catfish (Ictaluridae), and sunfish/bass (Centrachidae) occur primarily in the weed beds of the littoral zone. However, much of the near-shore warm waters of Otsego Lake are devoid of plants and cover. In these areas, warm-water fish still dominate, though their populations are greatly reduced.

Otsego lake is morphologically oligotrophic. It is characterized by a very limited littoral zone which warms slowly, delaying the start and limiting the length of the spawning season of most warm-water fish. Further, the littoral zone is often subj ected to extreme temperature changes which often interrupt spawning and reduce spawning success of these fishes. This results in large peaks in year class strength. These same factors impact growth, these fishes being small in size and having relatively slow growth.

During the summer, the near-shore littoral fish fauna consisted of 18 species in 9 families (Table 4). No single taxon of fish obviously dominates these areas, though the white sucker, golden shiner, chain pickerel, brown bullhead, rock bass, and pumpkinseed are abundant. Additionally, a few cold water fish such as lake trout (Salvelinus namaycush), Atlantic salmon (Salmo salar), and cisco (Coregonus artedii) frequent these waters in early June and mid-late September.

In near-shore waters, the catch-per-uni t-effort (cpue) was remarkably similar in 1989, 1990 and 1993 (Table 4). Peak catches of maj or littoral zone fish predators, such as smallmouth bass, rock bass, and chain pickerel in 1991 and 1992 corresponded with peak alewife abundance (Table 2) .

Over the 5-year period, Atlantic salmon populations appeared to increase in near-shore waters, while golden shiner, white sucker, and brown bullhead were decreasing (Table 4).

THE PROFUNDAL FISH FAUNA OF OTSEGO LAKE

The deep-water fish fauna was sampled with a coarse twine experimental gill net (300' by 8': 1.5, 2.0, 2.25. 2.5, 3.0, 3.5 inch mesh) and trammel net (300' by 8', 1" inner mesh, 12" outer mesh). Nets were set in an east-west orientation east of the BFS dock at a depth of 50-60 feet (i.e. below the thermocline). The coarse twine used on the sampling nets were ineffective on slender fish like the alewife, and the smallest mesh sizes were too large to accurately sample small fish such as sculpins and smelt.

Family Species 1989 1990 1991 1992 1993 Mean

Salmon/Trout Lake Trout Atlantic Salmon

.3 .1 1.4 2.2

.1

.7

Cisco Cisco 1.8 .4

Herring Alewife .3 .1 .1

Suckers White Creek

Sucker Chuhsucker

11.3 8.4 8.5 9.9 .6

4.4 .2

8.5 .2

Minnows Carp Golden Shiner

1.3 7.0

.9 7 . 6

.8 10.0

.7 1.4

2.6 1.9

1.3 5.6

Pickerel Chain Pickeral 4.0 5.6 14.0 11.1 7.9 8.5

Catfish Brown Bullhead 7.8 7.6 10.0 1.4 1.9 5.7

Sunfish/Bass Rock Bass Redbreast Sunfish Pumpkinseed I3luegilJ Smallmouth Bass Largemouth Bass

3.0

3.3

.3

.3

3.1 .4

5.0

1.1 .6

.3

13.3 .3

9.0 1.5 2.3

6.4 .1

6.9

3.1 .7 .1

4.2

8.7

.4

.3

.2

6.0 .2

6.6

1.3 .8 .1

Perch Yellow Perch Walleye

2.5 3.0 2.8 .1

3.0 1.7 2.6 .0

Mean Catch 43.2 43.8 75.8 57.8 43.3 52.8

Table 4. Summer fish abundance (June-september) at 8-30 foot depth within the littoral zone off Rat Cove. Catch per unit effort data are based on paired monthly 24 hour sets of trammel nets and experi mental gi II nets,

N ....... o

211

Because of its steep sides and great depth, most of the waters of Otsego Lake are deep and cold. However, fish abundance in these areas is very low and variable. Approximately 3.5 times as many fish are present off Rat Cove in 8-30 feet than at 50-60 feet (Table 46d versus Table 5). It was not uncommon to pull up a 300' foot deep-water net with no fish in it.

Otsego lake cold-water fishes commonly associated with the lake bottom include the lake trout, whitefish (C. clupeaformis) , burbot (Lota iota), and slimy sculpin (Cottus cognatus), while those occurring in open waters include the Atlantic salmon, cisco, and rainbow smelt (Osmerus mordax). Cool-water species (e.g. alew~fe, white sucker, and yellow perch) are also a common component of deep waters. The presence of small numbers of warm water fish, such as carp, golden shiner, pumpkinseed, and bluegill at 50- 60 feet is very uncommon (Table 5) (Scott and Crossman, 1973) .

Otsego Lake's deep water fish fauna consists of approximately 14 species in 8 families (Table 5) . White sucker and cisco initially dominated the deep-water fish fauna, making up 80% of the catch. However, over the course of the 5-year study, populations of both species dropped drastically.

FISH FAUNA OF ROCKY SHOALS

The rocky shoal fish fauna was sampled with a coarse twine experimental gill net (300' by 8': 1.5, 2.0, 2.25. 2.5, 3.0, 3.5 inch mesh) and trammel net (300' by 8', 1" inner mesh, 12" outer mesh). Nets were set perpendicular to shore from 8 feet in depth to 60 feet and thus extended from warm epilemnetic waters, through the thermocline, into cold, hypolirnnetic waters. Virtually 100 per cent of fish captured in these nets were adults.

While rocky shoals are one of the most common habitats in Otsego Lake, fish abundance in these areas is very low. Approximately 4 to 4.5 times as many fish are present in weedy, littoral areas such as Rat Cove then were captured near rocky drop offs such as Point Judith (Table 1) and Point Florence (Table 4) vs. Table 6).

The fauna of rocky dropoffs (8-60' depth) consists of approximately 21 species in 11 families during the summer (Table 6). However, over half the fish have such a low catch per unit effort (.1 or less) that they are classified as being rare. No group of fish dominates rocky shoals, although the white sucker, lake trout, cisco, rock bass, and pumpkinseed are relatively common.

Family Species 1989 1990 1991 1992 1993 Mean

Salmon/Trout Lake Trout Atlantic Salmon

.5

.5

1.5

.6

.3 .5 .2

cisco Cisco Whitefish

6.8 .'6

23.8 7.4 1.1 .1

.9

.7 8.0

.3

Herring Alewife .5 .1

Suckers White Sucker 10.8 5.0 3.8 1.3 .7 4.3

Minnows Carp Golden Shiner 2.3

.1 .0 .5

Pickerel Chain Pickeral .3 .1

Sunfish/Bass Rock Bass Pumpkinseed 131uegill Smal1mouth Bass

2.4 2.8

.2

.1

.0

.5

.6

.0

Perch Yellow Perch .2 .5 1.2 .4

Mean Catch 23.6 30.8 11.2 8.7 2.7 15.4

Table 5 . Summer fish abundance (June-September) at 50-60 foot depth at center lake off Rat Cove. Catch per unit effort data are based on paired Monthly 24 hour sets of trammel nets and experimental gill nets.

N -'" N

Family Species 1989 1990 199: 1992 ~ S:j ~j Mean

Salmon/Trout LaKe Trout Atlantic Salmon Brown Tro·ett

1.2

.2

1.0.. .9 .8

2.8 1.8

1 " "

L.

.2

Cisco cisco Whltefish

4.5 2.6 1.2 . 1

.1

.1 . , 1 '7

. "

Smelt Rainbow Smelt .2 .0

Suckers Wh~te Sucker 7 .8 1.0 1.0 2 .• S.l 3 5

Minnows Carp Spot tail Shiner .2

.2 4 1.3 -/ .9 .8

.0

Pickerel Chain Pickeral .2 .1 .f

Catfish Brown Bullhead .1 .'i 1

Cod BtlIbot 1 .0

Sunfish/Bass Rock Bass Redbreast Sunfish Pumpkinseed Bluegill Smdllmouth [lass Largemouth Bass

4.5 .3

.2

.2

.8

.5

.2

.2 1.2

1.5

.2 1.0

.8

2.1

c, . 4

.1 ';

OJ

1 8

1 ] .3

. 1 8

.1

Perch Yellow Perch Walleye

1.2 .? .4 . 6 (, .6

.0

Sculpins Sllmy Sculpin .2 ()

Mean Catch 20.2 7.1 7 .1 129 20."7 13 6

Table' 6, Summer fish abundance (june-September) at 8-60 foot depth off the rocky drop­off at Point Florence. Catch per unit effort data are based on paired monthly 24 hour sets

of trammel nets and experimental gill nets.

I\) -0.

W

214

While the fishes of rocky shoals typically include warm-water, cool-water and cold-water fishes, cool-water fishes often predomi­nate. Cool-water fishes are characterized as being spring spawners whose su@ner distribution can include deep hypolimnetic waters as well as warm littoral and epilimnetic waters. White sucker, alewife, and yellow perch are the major cool-water fish of Otsego lake.

The fauna of rocky shoals varies considerably from year to year (Table 6). Low catch rates and high fluctuations in catch indicate that fish occurring on rocky shoals are primarily transients. SCUBA surveys indicate relatively little cover, and few fish maintain stations on the bare rocky areas along the eastern side of the lake.

From 1989-1993, there appeared to be an overall trend for warm water fish populations to increase on rocky shoals (e. g. carp, bullhead, rock bass, pumpkinseed, and smallmouth bass). While most warm-water piscivore populations, such as chain pickerel, smallmouth bass, and largemouth bass peaked in 1993, there was a peak in deep-water fish predators, lake trout and Atlantic salmon, in 1992. Two walleye (Stizostedion vitreum) were captured in that year as well.

Yellow perch, rock bass, and white sucker, fish typically associated with cool waters, had similar population trends on rocky shoals (Table 6). Cisco populations dramatically decreased from 4.5 fish per 24 hour set to 0 during the 5 year study.

FISH FAUNA OF OPEN SURFACE WATERS

Pelagic epilimnetic waters were sampled with very light, multifilament experimental S\vedish gill nets (300' x 5', 25' panels of 1.5, 2.0, 2.25, 2.5, 3.0 and 3.5' stretch mesh) at the center of the lake off Rat Cove from 1989-1991. Catch was extremely low, with only 10 alewives, 8 golden shiners, 1 European rudd, 1 emerald shiner, and 1 carp captured in 14-24 hour sets.

In the early 1980s, emerald, spottail, and rosyface snlners were abundant in open waters of Otsego Lake (MacWatters, 1980; 1983) . In 1988-1989, schools of emerald shiners were clearly visible during the day and open water gill net surveys substantiated their presence. However, during the sU@ners of 1990 and 1991, alewives were the only species gill netted in open waters off Rat Cove.

The golden shiner \vas the dominant species captured in open water in the late 1980s. This species is considered to be very adaptable to changing ecological conditions (Smith, 19(9) and was

215

3) Decline in Planktivorus Species: The alewife, a schooling planktivore that occurs throughout Otsego lake, comes into direct competition with other maj or planktivorus species. Following a similar pattern documented in the Great Lakes (Smith, 1970), alewife activities appear to have eliminated or greatly reduced other planktivores, such as emerald shiners, spottail shiners, rosyface shiners, blackchin shiners, bridle shiner, and spotfin shiners. Deep water pelagic planktivores such as cisco and smelt have also experienced population crashes.

4) Los s of Littoral Zone Species: Recent ly, the species composi tion of the littoral zone has undergone maj or losses. Six species apparently have disappeared from the littoral zone entirely (American eel, redfin pickerel, blackchin shiner, rosyface shiner, spotfin shiner, and margined madtom) .

5) Changes in Forage Base: Historically, various minnow species, smelt, and cisco formed the forage base of Otsego Lake. Recently, these have been replaced by the alewife. The fish ecology of Otsego lake rapidly changed from a relatively broad forage base to an unstable forage base dependent on a single species.

6) Change in Fish Distribution: Catch data provide numerous examples of changes in fish distribution. For example, golden shiners, which previously occurred in limnetic (night) and littoral waters (day) appear to be restricted to the littoral zone since alewife introduction. Stream species, such as creek chub, blacknose dace, longnose dace, and common shiner, which were prevalent in inshore lake waters of stream mouths, no longer occur there. Emerald shiners and spottail shiners, once widely distributed in limnetic and littoral waters, appear to be concentrated in the northern inshore waters and stream mouths.

7) Loss of Large Predacious Fishes: Natural reproduction no longer maintains adequate populations of most large piscivorous fishes. Walleye and burbot are virtually extinct in Otsego Lake, as evidenced by catch data, spawning surveys (Lehman et ai., 1991), and angler surveys (Foster et ai., 1992). Only 2 walleye and 1 burbot were captured after approximately 160 sets of 300 foot gill nets and trammel nets between 1989-1993. Earlier authors describe walleye as a major piscivore in Otsego Lake (Harman et ai., 1980; MacWatters, 1980). Atlantic salmon can only be maintained, and lake trout

216

not present in pelagic waters in the early 1980s when the rosyface, emerald, and spottail shiners dominated these areas (MacWatters, 1981) . Thus, it would appear that the golden shiners began utilizing open waters at night to feed on zooplankton (as described by Werner et al., 1977) in the late 1980s before being driven from these waters by competition with alewives in the early 1990s.

THE STATE OF THE FISH FAUNA

Near-term and long-term trends in the fish communities of Otsego Lake have been impacted, or result from, the following phenomena:

1) Introduction of Fish Species by the Public: The release of fish by anglers likely plays a primary role in adding new species to Otsego lake. Recent surveys indicate that six species have been added to the fish fauna of Otsego lake in the past 15 years. One of these (alewife) has become very abundant, three have become common (European rudd, smelt and fathead minnow), while the other two are presently rare (fallfish and channel catfish). Fishermen apparently had a role in introducing all six species either through bait bucket introductions (European rudd, fathead minnow, and fallfish) or through deliberate a t tempt s to enhance the fi shery (smelt, alewi fe, and channel catfish). Bait-bucket releases are also suspected to have resulted in the introduction of banded killifish (MacWatters, 1983). Species introductions have had a significant impact on short-term and long-term changes in relative abundance and species composition of Otsego Lake. Alewife, in particular, which occurs in all lake zones, has had a tremendous influence on both cold­water and warm-water fish populations, as well as on other biological and physical lake conditions.

2) Introduction of Fish Species by the State: State sponsored fish sLocking programs have played a critical role in adding and maintaining fish in Otsego lake. Lake trout populations are maintained by lake stocking, and brown trout populations are at least partially maintained by stream stocking. Atlantic salmon were stocked from 1982-1992, initially in an attempt to manage populations of the introduced rainbow smelt (Sanford, 1986). Historically, whitefish and walleyes were the major sport fishes. Concurrent with the 1955 introduction of ciscos, their catches declined (NeHell, 1976) and cisco became the dominant sport species. Since the introduction of alewives, cisco, in turn, has declined markedly.

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augmented, through stocking.

8) Ecosystem Imbalance Regarding Predator Control of Forage Species: Pi scivores normally control populations of forage species so that problems of die-off or competition with other desirable species do not occur. Evidence that predators do not control forage species in Otsego lake are: (1) predators did not prevent the colonization and irruption of the alewife population (Smith, 1970); (2) catch data indicated a relatively low predator to prey ratio; and (3) die-offs of cisco and alewife, as well as thei r poor condition and growth (Foster, 1993; Frost, 1993), and the poor growth of pan fish (MacWa t ters et al., 1988) indicate that forage populations are limited by food rather than by predation.

9) Decrease in Cool-water Fish Populations: Combined trammel net and gill net catches from three sample sites indicate significant population drops for most cool-water fish. Total population of yellow perch declined from 1989 through 1991 (cpue = 3.9, 3.7, 3.2 in 1989, 1990, and 1991, respectively), rebounded in 1992 (cpue = 4.8), and dropped sharply in 1993 (cpu = 2.3). Drop in yellow perch populations were confirmed by angler surveys (Foster et al., 1992). Populations of white sucker also dropped steadily from 1989 (cpue = 29.9) to 1993 (cpue = 10.2). Only two walleye were captured over the study period.

10) Decline in Cold-water Fish Populations: While Otsego Lake is dominated by deep cold waters, cold-water fish do not dominate the fish fauna. Currently, populations of cisco, whitefish, smelt, burbot, and sculpin appear to be extremely low and dropping. Only lake trout populations, which are maintained by stocking, appeared stable. Atlantic salmon are still common. However, as this species is not reproductively self-sustaining in Otsego Lake (Sanford, 1986), stocking must be resumed in order for this population to be maintained. Competition with introduced species is the major factor effecting changes in fish fauna. For example, the cisco population crashed (Frost, 1993), smelt drastically declined, and whitefish continued its earlier decline (Foster and Gallup, 1991) following the recent addition of alewives. Body composi­tion of ciscos and whitefish indicate that starvation, presumably due to alewife competition, is the primary cause of the recent decline of these species (Keenen and Ketola, 1993)

11) Very Low Fish Populations Around Rocky Shallows and DrQp­

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~: Sampling with various types of gear indicate fish populations on rocky substrates are extremely low. Shoal-living fish (smallmouth bass, rock bass, and yellow perch, etc.) congregate in reef areas where adequate cover is present. SCUBA observations indicate cover here is lacking.

12) MarQinal Warm-water Fish Habitat: Many warm-water species had significant fluctuations in year class strength, and stunting was evident (Austin et al., 1988). Limited growing season and interruptions of spawning and growth periods by meteorological events seem to limit the production of warm-water fish.

REFERENCES

Austin, J.E., R.C. Macwatters, W.N. Harman, and R.M. Harman. 1987. Age and growth of eleven fish species in littoral areas of Otsego Lake. In 19th Ann. Rept., 1986. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 36-58.

Emery, A.R. 1973. Preliminary comparisons of day and night habits of freshwater fish in Ontario Lakes. J. Fish. Res. Bd. Can. 30:761-774.

Fos ter, J. R. 1990. Introduction of the alewi fe (Alosa pseudoharengus) into Otsego Lake. In 22nd Ann. Rept., 1989. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 107-111.

Foster, J.R. 1993. Alewife Population Dynamics in Otsego Lake. In 25th Ann. Rept., 1992. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 120-124.

Foster, J.R., T. Good, A. MacDuff, M. Moulton, R. Woods, J. Almer, and V. Knight. 1992. The ice fishery at Otsego Lake. In 24th Ann. Rept., 1991. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 206-216.

Foster, J.R., and S. Gallup. 1991. Irruption of the alewife population of Otsego Lake . .In 23rd Ann. Rept., 1990. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 56-59.

Frost, J.A. 1993. Decline of cisco (Coregonus artedii) in Otsego Lake. In 25th Ann. Rept., 1992. SUNY Oneonta Bio. Fld. Sta., SUNY, Oneonta. pp. 125-128.

Harman, W.N., L.P. Sohacki, and P.J. Godfrey. 1980. The limnology of Otsego Lake. In Bloomfield, J.A. (ed.) Lakes of New York State. Vol. III. Ecology of East-Central N.Y. Lakes. Academic

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Press, Inc., New York. pp. 1-128.

Keenen, C.H. and H.G. Ketola. 1993. Composition of whitefish and cisco flesh captured in Otsego Lake in 1969 and 1992 and possible influence of the introduction of alewives on their forage. .In 25th Ann. Rept., 1992. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 112-119.

Lehman, K., W. Will iams, and J. Foster. 1991. Extinction of walleye (Stizostedion vitreum) in Otsego Lake. In 23rd Ann. Rept., 1990. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp 52-55.

MacWatters, R.C. 1980. The fishes of Otsego Lake (1st ed). Occ. paper #7, SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.

MacWatters, R.C. 1983. The fishes of Otsego Lake (2nd ed). Occ. paper #15, SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.

MacWatters, R.C., T. Sioussat, and C. Sohacki. 1981. The distribution of selected fishes of the littoral zone of Otsego Lake with remarks on associations with major macrophytes and bottom types. l.n 13th Ann. Rept., 1980. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. pp. 56-67.

New, J.G. 1971. Vertebrate studies. .In 3rd Ann. Rept. , 1970. SUNY Oneonta Bio. Fld. Sta. , SUNY, Oneonta. pp. 1-3.

New, J.G. 1973. Vertebrate studies. l.n 5th Ann. Rept. , 1972. SUNY Oneonta Bio. Fld. Sta. , SUNY, Oneonta. pp. 48-53.

Newell, A.J. 1976. The relationship of age, growth, and food habi ts to the relative success of the whitefish (Coregonu5 clupeaformis) and the cisco (C. artedii) in Otsego Lake, New York. Occas. Pap. No.2, SUNY Oneonta Bio. Fld. Sta., SUNY, Oneonta.

Sanford. O.K. 1986. New York State Department of Environmental Conservation, Region 4, Stamford, New York (unpublished report) .

Scott, W.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Bull. Fish. Res. Bd. Can. 184: 1-966.

Smith, P.W. 1979. The fishes of Illinois. Univ. of Illinois Press.

Smi th, S. H. 1970. Species interactions of the alewife in the Great Lakes. Trans. Am. Fish. Soc. 99(4): 754-765.

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Werner, E.E. 1977. Habitat partitioning in a freshwater community. J. Fish. Re. Ed. Can. 34: 360-370.