WILLARD N. BROWNELL and JOHN M. STEVELY

The Biology, Fisheries, and Managementof the Queen Conch, Strombus gigas

Introduction

The queen conch, Strombus gigas(Fig. 1), a large marine snail, has beena principal source of food for the in­habitants of Caribbean coasts andislands since the first American Indianssettled there long ago. Today it re­mains an important source of proteinin the region, while imports by theUnited States have grown. However,stock depletion is now occurring inmany areas due to overfishing.

This particular conch is one of sixspecies of the family Strombidaefound in the Caribbean and Florida,and is by far the region's most impor­tant mollusk. Queen conchs are heavilyfished throughout most of their rangefrom Bermuda and southern Florida,all around the Caribbean, south to

Cayenne (Fig. 2). Besides conch (pro­nounced "konk"), they are alsoknown as botuto (Venezuela), cam­bombia (Panama), carrucho (PuertoRico), cobo (Cuba), guarura (Los Ro­ques), lambie (Windward Islands),and lambi (Hispaniola). They are alsofrequently called "pink conch."

In some places, such as the CaicosBank, conchs with thick, stubby shellsand leathery black skin are found.These are called "samba" or "sanga"

Willard N. Browell is with the Complex SystemsResearch Center, O'Kane House, University ofNew Hampshire, Durham, NH 03824. John M.Stevely is with the Marine Advisory Program,University of Florida, 1303 17th St. W., Palmet­to, FL 33561. Views or opinions expressed orimplied are those of the authors and do notnecessarily reflect the position of the NationalMarine Fisheries Service, NOAA.

Figure I.-Adult queen conch,Strombus gigas.

conchs. Fishermen consider them tobe a different, and far less desirable,animal, while biologists say they aresimply a morphological variation ofthe queen conch (Randall, 1964).

Economically, the queen conch isnow the second most valuable Carib­bean fishery resource after the spinylobster. As a protein resource it hasbeen second only to finfish in nativediets for at least 100 years. In addition

Figure 2.-Geographic distribution of queen conch, Sfrombus gigas (afterWarmke and Abbott, 1961).

GULF of MEXICO

ABSTRACT-Available informationon the biology, FISheries, and culture ofthequeen conch, Strombus gigas, throughoutits geographic range, is reviewed. Begin­ning in the early 1970's, development ofalucrative frozen conch meat market in theUnited States dramatically increased theeconomic significance of the queen conch.However, the current condition of severalconch fisheries indicates that these stocksare insufficient to meet demand. Someconservation measures have been imple­mented, but lack offisheries biology dataand FISheries personnel hamper develop­ment of comprehensive managementplans. Problems with stock depletion havefocused attention on the possibility ofconch culture and/or stocking. In recentyears a number of small, local researchprojects have been initiated to study queenconch biology and larval rearing. How­ever, expanded research is needed todevelop larval culture techniques appli­cable fo pilof scale hatchery operation.

July 198/,43(7) /

Figure 3.-Strombus gigas laying eggs in 3 m (10 feet) of water off the Bahamas.

to the value of the meat, the brightlycolored shell is often sold for orna­mental purposes and was once used inthe manufacture of lime and porcelain.Occasionally, an irritating particlelodged between animal and shellresults in production of a conch pearl.Although these pearls often have highmarket value, demand for them islimited since they fade with age.

Today, rapidly expanding humanpopulations throughout the regionhave brought more modern fishingmethods, more sophisticated process­ing and marketing structures, and thequeen conch has been overfished overmost of its range. Catches in mostareas now are not even sufficient tosatisfy local demand, much less totake advantage of lucrative exportmarkets. This paper reviews thebiology and fisheries of the queenconch and also considers managementand research strategies for its restora­tion and culture.

Biology

Habitat

Queen conchs commonly inhabitsandy bottoms that are stable enoughto support the growth of some of thenumerous species of algae and sea­grasses upon which they feed. Theyare also found on gravel, coral rubble,and smooth hard coral or beach rockbottoms. Queen conchs may be foundin only a few inches of water or downto 76 m (250 feet), but they seldom godeeper than 30 m (100 feet) (Randall,1964). Restriction of queen conchs toshallower water has generally been at­tributed to limitations of light forplant growth (Randall, 1964; Robert­son, 1961). Small juvenile conchs( <:: 80 mm or 3.2 inches) are oftenburied in sand during the day and arerarely seen (Randall, 1964).

Food

The queen conch is one of thelargest of the herbivorous gastropodmollusks (Yonge, 1932), and uses along, higWy extendable proboscis tograze algae and seagrasses.

In general, Randall (1964) foundthat the dominant plants of a partic-

2

ular habitat in which conchs arefound tend to be the principal foods.Although seagrasses such as Thalassiaare consumed, various species ofalgae are the principal elements in thediet of S. gigas. Robertson (1961)observed conchs feeding on the epi­phytic algae on Thalassia but foundno Thalassia leaves in the gut. Henoted four species of algae that wereingested by Strombus: an unidentifiedblue-green, Cladophora sp., Hypneacervicornis, and Polysiphonia sp.Conchs may ingest considerablequantities of sand while feeding onfIlamentous and unicellular algae(Robertson, 1961; Randall, 1964).Small benthic animals found in thegut are believed to have been acciden­tally consumed (Randall, 1964).

Preliminary studies by Hesse' havefound that food preferences of thequeen conch change over the courseof a year. Although probably due inpart to variations in availability ofplant species, apparently there is alsoa clear seasonal difference in thedesirability of certain food sources.Feeding by conch during the nightwas reported by Randall (1964), and

IChuck Hesse, PRIDE, Pine Cay, Turks andCaicos Islands, B.W.I., pers. commun.

immature animals in particular tendto feed most actively at night, whileoften spending most or all of the dayburied in the sand.

Reproduction

Copulation and spawning occurduring the warmer months of the year(Brownell, 1977; 0'Asaro, 1965; Ran­dall, 1964), although in some areasreproductive activity may occur yearround (Blakesley, 1977). Fertilizationis internal. Under protection of theflaring lip, the penis is extendedthrough the siphonal notch and upinto the genital region (Berg, 1975).Randall (1964) observed conchs copu­lating at night as well as by day. Initialcopulation precedes spawning by sev­eral weeks (0'Asaro, 1965; Randall,1964).

Generally, females produce eggmasses in clean coral sand with a loworganic content. Production of theegg mass (Fig. 3) takes 24 to 36 hours(Randall, 1964; 0'Asaro, 1965). Theegg mass consists of a long contin­uous tube which folds and stickstogether in a compact mass. Adheringsand grains provide camouflage. Thenumber of eggs per egg mass has beenestimated at between 313,000 and485,000 (Robertson, 1959; Randall,

Marine Fisheries Review

Figure 4.-Top left is a four­lobed Strombus gigas veligershowing beginning formationof third pair of lobes at 10-12days old. Six-lobed veliger(top right) 15 days old. Belowright is a settled larva justprior to metamorphosis.Foot can be seen at upper leftof photo, below the shell.

Table 1.-Calculated lengths of queen conch at 1,2, and 3 years of age.

1964; D'Asaro, 1965). Laying ofmore than one egg mass per breedingseason by the queen conch and otherStrombus sp. has been suggested byseveral investigators (Robertson,1959; Randall, 1964; Berg, 1975).

The larvae, or veligers (Fig. 4),emerge from the egg cases after ap­proximately 5 days (D'Asaro, 1965)and immediately assume a pelagiclifestyle, feeding on small phyto­plankton. If conditions are right, theveligers settle to the bottom at17-22 days after hatching, althoughthey continue to be plankton feeders(Brownell, 1977). Metamorphosis iscomplete (development of the probos­cis, disappearance of velar lobes) at28-33 days (Brownell, 1977). However,larval development can be extremelyslow if the supply of phytoplanktondoes not provide the appropriate typesand quantities of required organisms(0'Asaro, 1965; Brownell, 1977).

Growth

Several investigators have estimatedqueen conch growth rates (Table 1).Estimates of mean length (tip of spireto distal end of siphonal canal) haveranged from 7.6 cm to 10.8 cm (3 to4.3 inches) for yearling conch, from12.6 cm to 17.0 cm (5 to 6.7 inches) atthe 2-year mark, and from 18.0 cm to20.5 cm (7.1 to 7.9 inches) at the endof the third year (Fig. 5, 6).

July 198/,43(7)

Lengths (em) and years

8.8 12.6 18.0

7.6 12.8 18.0

10.8 17.0 20.5

No 17.0 18.6data

Method of calculation(geographic location) Reference

Size frequency distribution of natural population (Puerto Rico) Berg (1976)

Size frequency distribution ot natural popuiation (Venezuela) Brownell (1977)

Von Bertalanlfy growth curve analysis of Randall's 1964 Berg (1976)tag/recapture data (Sf. John. U.S.V.I.) Brownell et al. (1977)

Von Bertalanffy growth curve analysis of nine populations using Alcolado (1976)tag/recapture data (Cuba)

3

Figure 6.-Size series of queen conchs raised at the Los Roques, Venezuela, sta­tion (largest is 18.0 mrn long). Photo courtesy of C. Berg.

4

Figure 5.-A photo­micrograph of aStrombus gigas ju­venile 20 daysafter metamor­phosis (4 mrnlong; 95 x). Photocourtesy of ScottSiddall, RosensteilSchool of Marineand AtmosphericScience, Universityof Miami.

Hesse2 and Berg (1976) estimatedthat at an age of 2.5-3.0 years theconch stops building the shell in aspiral fashion and starts building theflaring lip (Fig. I). At this time, theanimal will continue to grow moremeat, but at a much slower rate. Oncethe shell lip begins forming, more ofthe total weight is made up of shellweight and nonmarketable viscera.Queen conch most commonly reachan acceptable market size of 18.8 em(7.5 inches), with a total weight of 845g (29.6 ounces), and a meat yield of100 g (3.5 ounces) at age 2.5 years(Berg, 1976).

Sexual maturity is attained after theflaring lip is well developed at an ageof 3-3.5 years (Hesse, footnote 2;Berg, 1976). Thus, queen conchsreach marketable size before they aresexually mature. Berg (1976) esti­mated mean longevity to be 6 years.

Queen conchs with the broadestflaring lips are not the heaviest. Whenfirst laid down, the lip is thin and verybroad. Soon, boring organisms andnormal wear begin to erode the shell,and the thin outer lip crumbles.Periodically, what remains of the lipis repaired with new shell. A progres­sively shorter but thicker lip is theresult (Randall, 1964).

Movements and Migrations

Parker (1922) described the uniquelocomotion of the queen conch. Theconch thrusts its foot against the sub­strate, causing the shell to be liftedand thrown forward in a hopping mo­tion. Berg (1975) suggests that this"hopping" motion may be of consid­erable adaptive significance. Mostgastropods glide along by muscularwaves of the foot, leaving a contin­uous chemical "scent" which enablesnight-feeding predaceous gastropods,octopuses, and crustaceans to "track"them; the conch's characteristic motiondoes not result in such a clear trail forthese predators to follow.

'Hesse, C. 1975. The conch industry in theTurks and Caicos Islands. Unpubl. manuscr.,18 p. PRIDE, Pine Cay, Turks and CaicosIslands, B.W.I.

Marine Fisheries Review

Caicos Islands. Fishing trips last 1-5days, with the fishing grounds notnormally being more than a I-day sailaway. The conchs are kept in corralsor in the live-wells of the boat untiljust before leaving for market withfresh meats. Sometimes they aretaken to market in the shell. In thepast, they were commonly dried in thesun or salt-dried during the fishingcampaign.

Currently, small boats with out­board motors have become popularfor getting out quickly to increasinglydistant conch grounds (particularly inthe Turks and Caicos). They are alsoan important status symbol for youngfishermen. Traditional native boatswith small inboard engines are stillused in many places, such as Vene­zuela, Colombia, and the DominicanRepublic. The fisherman's profitmargin continues to decrease as bothfuel consumption and costs increase,in spite of increasing conch prices.

Most fishermen today are free­divers (Fig. 7), using a face mask andfillS to retrieve as many as eight conchsat a time, or to fill a heavy net bag tobe hauled from the boat. A good

........- (~.-

Figure 7.-Young conch divers working near Gran Roque Island, Venezuela.Photo courtesy of H. Lander.

--

believe that these fishes had consumedqueen conch after some other preda­tor had made the soft part available.Hesse (footnote 2) indicated thatoctopus and perhaps nurse sharksalso prey upon queen conchs.

Once the queen conchs are fullymature, predation by marine animalsis apparently limited to large hermitcrabs, certain sharks, rays, and seaturtles (particularly loggerheads), andpossibly large octopus. Long beforematurity (starting at a length of about12 cm), the most dangerous queenconch predator is man.

Fishing Methods

Historically, sailing sloops 6-11 m(20-35 feet) long were used for har­vesting conch. These sloops sailed togood fishing areas and several menfished from small dinghies. The bot­tom was scanned with a glass­bottomed bucket until a conch islocated. A pole up to 9 m (30 feet)long was then used to hook the conchand bring it to the surface.

This method is currently practiced,to a limited degree, only in theBahamas, Bermuda, and Turks and

Predation

Randall (1964) reported the follow­ing species as predators of the queenconch: Tulip shell, Facio/aria tu/ipa;Florida horse conch, P/uerop/ocagigantea; Murex pomum; hermitcrab, Petrochirus diogenes; spinylobster, Panu/irus argus; spotted eagleray, Aetobatis narinari; permit,Trachinotus fa/catus; hogfish,Lachno/aimus macunus; queen trig­gerfish, Batistes vetu/a; and porcupinefish, Diodon hystrix. Eight species offish (groupers, snappers, and grunts)with remains of queen conchs in theirstomachs but without dentition tocrush large shells led Randall (1964) to

Field studies in the Turks andCaicos Islands by Hesse (1979) havegreatly added to our understanding ofqueen conch movements and migra­tions. Queen conchs migrate seasonal­ly: Inshore during spring and offshoreduring autumn. Seasonal regularity ofmigrations was found to increase withage. Hesse (1979) was also able toestimate a "home range" (area overwhich a conch habitually travelledwhen not involved in seasonal migra­tions) for different size classes.Juveniles from 10 10 13 cm (4 to 5.2inches) long usually remained withina home range of 1,000 m' and mostconchs from 13 to 16 cm (5.2 to 6.4inches) exhibited ranges from 2,500to 5,000 m'. Conchs 17 cm long sooften moved out of the survey areathat meaningful home ranges couldnot be determined. Adult conchs ap­peared to range several kilometers.Tag-recapture studies yielded returnsup to 2 km distant as little as 2months after tagging. Tagged adultswere found to commonly move alotal linear distance of 50- I00 m a day.

Hesse (1979) observed that conchs ofall ages periodically bury into thesubstrate, often in response to winterstorms. Longer term burying (up to 6weeks) occurred independent of dailyweather conditions and indicatedperiods of dormancy, which frequentlyoccurred immediately prior to repro­ductive activity. Randall (1964)suspected that burying was mainly forthe purpose of depositing new shell.

July 1981, 43(7) 5

Figure 8.-Piles of discarded conch shells in the Las Aves Islands off the coast ofVenezuela.

Figure 9.-Laughing gull perched atop a pile of conch shells left behind byfishermen in Los Roques Islands. Photo courtesy of H. Lander.

Status of the Resource

The importance of the queen conchfishery has been noted and reviewedby several authors (Doran, 1958;Menzel, 1969, 1971; Boss, 1971;Gunter, 1971). However, it has onlybeen since the late 1960's that animport market for queen conch hasdeveloped in the United States, asgreater numbers of Caribbean peoplemigrated there (especially to NewYork City, south Florida, andCalifornia). Growing populations andtourism have also increased local de-

a cay or in their boats. This allows thefishermen to carry more meat tomarket, and at greater speed. Themeat is removed by knocking a smallelongate hole between the third andfourth whorls of a spire. A narrowsharp blade is inserted in the hole, andthe animal is cut free of its attachmentto the central axis of the shell. Atwisting motion can then be used toremove the animal. In order to keepthe shell intact, shell collectors freezeor boil the animal (although boilingmay result in fine cracks in the shell).The shells form huge mounds atpopular meat removal sites (Fig. 8, 9),or are simply thrown overboard.

Conchs consumed locally are solduncleaned from buckets at villagemarkets. Processing plants, the ma­jority of which are in Belize and theTurks and Caicos, prepare conch forexport to the United States. Teams ofcleaners remove the viscera and othersoft parts from the muscular foot andpeel away the tough dark skin. Thecleaned meat is washed and placed in2.3 or 4.5 kg (5 or 10 pound) plasticbags and cardboard boxes to befrozen, usually <12 hours from thetime the animal was removed fromthe shell.

The waste is used occasionally asbait for fish pots. The marketablemeat yield is about one-half the totalweight of the shelled animal.

Frozen conch meat is usuallyshipped by airplane, although occa­sionally it is transported by lobstercarrier boats or cargo ships. Most of itenters the United States throughMiami (Table 2).

stocks even more. Most conch diversalso gather lobsters, usually on dif­ferent days or during differentprescribed seasons.

Processing and Marketing

Nearly all present-day fishermencut the animal out of the shell near thefishing grounds, either on the shore of

diver can gather 600 conchs in 4 hoursof work on a productive ground in 3-7m (10-23 feet) of water. But, since avery small portion of the remainingconch stocks can now be found in< 7 m (23 feet), many fishermen areturning to scuba gear for gathering indeeper water, thus increasing theirharvesting costs and depleting the

6 Marine Fisheries Review

Table 2.-Conch meat (x 100 kg) imported through Miami, 1970·78.

Country of origin 1970 1971 1972 1973 1974 1975 1976 1977 1978

Belize 145.7 265.0 382.9 245.1 376.7 330.5 222.5 159.9 135.8Columbia 0 0 39.8 107.7 122.5 50.3 13.5 11.2 62.3Dominican Republic 0 0 0.5 24.4 10.1 O. 2.1 0 0Haiti 0 0 2.2 4.1 0 0.2 0.2 14.9 58.3Honduras 58.0 32.4 88.2 83.4 5.7 36.3 57.7 3.7 21.4Jamaica 0 0 1.5 4.1 28.5 40.7 0.8 0 0Mexico 0.2 0 8.6 2.2 0 11.7 3.2 1.8 1.5Turks and Caicos 2.0 2.3 0 0 0 65.9 150.9 221.7 262.8West Indies 0 0 1.2 22.1 3.9 7.2 2.2 0 0Other' 8.4 0.8 2.7 1.8 2.0 7.8 14.8 2.3 13.2Total 214.3 300.5 527.6 494.9 549.4 550.6 467.9 415.5 555.3

lBahamas, Cayman Islands, Costa Rica, Guatemala, Nicaragua, Panama, and Venezuela.Source: National Marine Fisheries Service, Fisheries Development Analysis Branch, New Orleans, La.Note: Approximately 27,000·32.000 kg of queen conch are imported to the United States each year directlythrough New York. Most of this comes from Belize, Honduras, and Colombia (J. Ledner, Nationai Marine FisheriesService, Fisheries Development Analysis Branch, New York, N.Y., pers. commun.l. Less conch (in fresh or driedform) enters the United States on small boats, mainly in south Florida.

1975Year

19701965

8 400~:;;; 300go:go-J

600,----------------,

Figure IO.-Queen conch landingsin the Bahamas, Belize, andVenezuela (meat weight). Sources:Bahamas (Henry Burrows, BahamasFisheries Department, Nassau, pers.commun.); Belize (Blakesley, 1977;data represent queen conch meatexported, estimated at 75-85 percentof total landings); Venezuela(Brownell et al" 1977),

'Henry Burrows, Bahamas Fisheries Depart­ment, Nassau, pers. commun.

500:'l

Bahamas

Although conch landings in theBahamas have declined (Fig. 10), thereare still collection boats that worktheir way through the islands(especially around the Abaco, An­dros, Berry, Eleuthera, and Exumaislands), buying conchs and deliveringthem to Freeport, Nassau, and Miami,either live or iced. Since fishablestocks within reach of villages andcamps are depleted, fishermen areforced to either terminate their effortsor travel to distant grounds.

To insure maximum local utilizationof the resource, export of Bahamianconch meat is prohibited. However,licenses are granted for the export offood products (conch fritters andchowder) that contain no more than40 percent conch meat. Conch shelljewelry and crushed shell for terrazzomanufacture can also be legally ex­ported. Retail prices in December 1979averaged US$4.29/kg (US$I.93/pound), for conch meat, and reachedas high as US$6.60/kg (US$2.97/pound) in winter3

•

Barbados

Apparently there never was an ex­tensive conch population around

than half the 1972 production. Re­duced abundance has been reported inthe Bahamas (Boss, 1971), the Grena­dines and Puerto Rico (Adams, 1970),Turks and Caicos (Hesse and Hesse,1977), and Venezuela (Brownell etaI., 1977).

The Conch Fisheries

The following observations on thestatus of queen conch fisheries inindividual Caribbean countries aremostly the result of a personal tour(July-September 1978) of the regionby the senior author, sponsored bythe FAO Inter-regional Project for theDevelopment of Fisheries in theWestern Central Atlantic (WECAF).

Antigua and Barbuda

Conchs are gathered all aroundAntigua and Barbuda. They used tobe sent on flights from Barbuda toPuerto Rico until they became hard tofind in the shallow waters of westernBarbuda. Local demand is still beingsatisfied in Antigua, where conch meatsold for US$I.l0/kg (US$0.50/pound) in 1978. Most conch collectingis now being done by native scubadivers, as the shallow water conchbeds have been picked clean. Dailycatch is loosely determined by the pro­jected market demand, as the womenfrom the villages who sell conch meatfrom buckets in the markets do notwant to have any left over at the end ofthe day. Small quantities of conch areair-shipped to Guadeloupe, along withregular exports of iced fish.

mand in countries which have tradi­tionally consumed queen conch.

In Belize (previously British Hon­duras), queen conch rose from 2.2percent of the value of fishery exportproducts in 1965 to 23.7 percent in1976, and the quantity of meat ex­ported rose from 50,000 kg (110,000pounds) to a peak of 561,000 kg(l,234,200 pounds) in 1972(Blakesley, 1977). Although export ofdried conch from the Turks andCaicos declined during the 1960's tothe point of being considered unim­portant by the local government, in­troduction of frozen meat to the U.S.market in the early 1970's resulted in adramatic increase of queen conchlandings (Hesse and Hesse, 1977).

Unfortunately, the available stocksof queen conch are insufficient tomeet today's demand. Althoughconch meat imports through Miamimore than doubled from 214,400 kg(471,680 pounds) in 1970 to 550,600kg (1,211,320) in 1975, in recent yearsimports have leveled off (Table 2) inspite of rising prices. Blakesley (1977)reported that the export price ofconch meat in Belize rose from 0.59Belize dollars/kg in 1965 to 3.30/kg in1976. In the Turks and Caicos, pricespaid to fishermen rose from US$O.06per conch in the 1960's to a 1978 priceof US$0.18 per conch.

Higher prices and improved market­ing structures have contributed tosevere stock depletion in most of theprincipal fishing areas around theCaribbean. In Belize total exportsdeclined to 211,000 kg (464,200pounds) in 1978, considerably less

July 1981,43(7) 7

Barbados. Older fishennen rememberonly occasional small catches thatwere consumed locally. Single animalsare still seen at times by scuba divers.

Belize

Conch production is monitored bythe Fisheries Department. There is aclosed season on conchs from 15 Juneto 30 September, and the minimumlegal size is 18.8 cm (7.5 inches). Aconch of this size yields 100 g (3.5ounces) of marketable meat. Conchdemand is high in Belize, but the highexport market value (US$3.19/kg orUS$I.44/pound for the year endingJune 1978) means that most is frozenand sold abroad. Within the market­ing range of the five fisherycooperatives in Belize, probably onlyabout 10 percent (the minimum re­quired by law) of the total catchreaches local markets. In the rest ofthe country all of the catch is soldlocally, except for small quantitiesthat are dried in fishing settlementsnear the Guatemalan border, and soldin that country by local traders. Insuch outlying areas, the catch rate isdetermined by daily market demand.

Conch meat exports from Belize(estimated at 75-85 percent of thetotal catch) rose sharply during thelate 1960's, but has drastically de­clined in recent years (Fig. 3).Although conch meat exports havesteadily declined since they reached apeak in 1972, rising prices have in­creased or maintained the value of ex­port sales (US$716,790 in 1976).

Conch fishing effort has slightly in­creased every year since 1973, but thecatch per diver per 4-hour day hasdecreased from about 36 kg (78.2pounds) of meat in 1975 to about 11kg (24 pounds) in 1978. Blakesley(1977) calculated the average size(shell length) of conchs caught to be19.1 cm (7.6 inches) in 1976. In1978-79 the managers of the cooper­atives were very concerned about thelarge number of juvenile conch meatsbeing delivered by fishermen, many inthe 50-70 g (1.8-2.5 ounce) range, in­dicating shell lengths as short as 12.0cm (3 inches).

8

Cuba

Conchs have been an importantresource on the southern shelf ofCuba for many years. They are pri­marily consumed in coastal villages,are often used for bait in fish pots,and are not exported.

Dominica

Conchs have apparently never ex­isted in significant numbers inDominica, due to the very limited ex­tent of stable, shallow bottom aroundthe island. Most of the conchs accessi­ble to free divers have long since beentaken, but small numbers are stillgathered when available by spearfish­ennen and are consumed locally.

Dominican Republic

The extremely narrow band ofshallow water around the DominicanRepublic is not conducive to highconch production. Nevertheless, theFisheries Department estimated acatch of 132,339 kg (291,146 pounds)in 1977. More than half of theamount harvested came from the off­shore banks (Mouchoir, Navidad,Silver, and the southern Bahamas).

Most of the Dominican artisanalfishermen based in the main northcoast port (Puerto Plata) use hookahair systems for spearfishing and thuscan gather conchs in deeper waterthan the average native fishermen.Two government agencies (Caza yPesca and INDOTEC) are concernedabout the conch fishery and haveidentified potential mariculture sites.

Grenada

The Grenada Grenadines andGrenada proper have traditionallybeen major suppliers of conch meat toTrinidad, Tobago, and Martinique.The Trinidad trade is basically fin­ished, except for small amounts ofconch that are shipped there from thenearly exhausted southeast coastfishery. The main conch grounds arein the north: Conference Point, Bed­ford Point, Carriacou, Petit Marti­nique, and all of the shallow waterssurrounding the small islands in thatarea. Some fishermen keep conchs in

natural corrals, bringing them inwhen the market is most favorable.Most conch divers now use scuba gearand work in depths averaging 12-15 m(40-50 feet).

Domestic conch consumption inGrenada is steady (7,000-9,000 kg or15,400-19,800 pounds/year), eventhough the price has more than dou­bled in recent years. Domesticmarkets for conch meat are undersup­plied by several tons each year. Quan­tities of conch meat equal to orgreater than domestic consumptionare shipped on ice through UnionIsland to Martinique markets'.

Haiti

Despite severe overfishing, Haitistill produces enough conch to supplysome local markets, and even to ex­port substantial amounts to Miami.Haitians are traditionally the mostdedicated consumers of conch in theCaribbean, and they account for alarge portion of the sales of conchmeat in Miami and New York. Evenin 1943, when there was still consid­erable local production, Haiti im­ported 3,900,000 dried conch meatsfrom the Turks and Caicos (Doran,1958).

Panama

Conch is still important in the dietsof residents of the Caribbean coast ofPanama, especially in the San BiasIslands, where most of the fishing ac­tivity occurs. Most of the catch is con­sumed by the Cuna Indian fishermen,but some reaches the markets ofcoastal towns. Some gets exportedalong with spiny lobster to Miami,but exports are sporadic.

St. Lucia

There are many bays and backreefareas in St. Lucia that offer suitablehabitat for conchs, but fishermenseldom find conchs in <:: 9 m ( <:: 30feet) of water anymore. Currently,they are taken mostly by scuba diving,

'Melvin Goodwin, Environmental ResearchProjects, Inc., New York, N.Y., pers. commun.

Marine Fisheries Review

25-50 at a time, and are either soldlocally or used for bait. Such effortsare very infrequent.

St. Vincent

The Fisheries Officer in St. Vincentis concerned about over-fishing ofconchs, especially in the St. VincentGrenadines, and wants to explore thepossibility of raising them somewherein those islands. No data exist on thecurrent yield of the conch fishery inSt. Vincent waters, but stocks haveevidently been depleted everywhere.The once-flourishing Union Island fish­ery (Adams, 1970) now produces only avery limited quantity of conch, most ofwhich is exported to Martinique.

Trinidad and Tobago

Trinidad has never been very pro­ductive for conch fishing, due to lowsalinities and high turbidity inshallow-water areas influenced by therunoff from the big continentalrivers and the numerous Trinidadianstreams. However, conchs were fairlyabundant in Bombshell, Chacacha­care, and Scotland Bays until theywere fished out several years ago.

Demand for conchs is still high inTrinidad, but the supply is verylimited. Only very rarely does a traderboat bring in a small load of iced ordried conch from nearby grounds(Grenadines or Los Testigos).

Tobago has traditionally producedenough conchs to supply local needs,but increased demand there and inTrinidad have led to severe over­fishing. Fishing effort there is nowvery sporadic, mainly occasional col­lection of some deeper water conchsfor sale to local hotels or for con­sumption by Tobago residents.

Turks and Caicos

For many years, beginning in thelate 1800's, millions of dried conchmeats were shipped from the Turksand Caicos Islands to Haiti (Dorna,1958). Following World War II thistrade began to decline. Early in the1950's there was some export offrozen conch to the United States.

July /981, 43(7)

However, in the mid-1950's, fishingeffort was shifted toward the newlydeveloped and more profitable exportof lobsters. By the late 1960's andearly 1970's, the Caicos conch tradewas greatly reduced and was neglectedby the local government. Queen conchswere fished principally for local con­sumption, lobster trap bait, and exportto Haiti. The catch amounted to only100,000-200,000 conches per year.

The importance of the queen conchfishery was reestablished in 1973 whenexport of frozen conch meat to theUnited States began again. Landingsquickly increased in the followingyears. The exports of conch for 1976totalled 1,900,000 individuals, valuedat US$470,000. Though accessiblestocks are rapidly being depleted,good catches are still being made, dueto the fact that there are more fisher­men with faster boats fishing far outon the southern and western edges ofthe Caicos Bank. In May 1978, theSouth Caicos processors were havinga difficult time keeping up with land­ings, often having to clean and freeze20,000 conchs or more in 1 day ateach facility. Since the ex-vessel pricewas $0.18 per conch at that time,divers who gathered 400 conchs in aday (as is commonly done) had verygood incomes.

However, the normal U.S. marketswere over-supplied at that time (May1978, just before the closed seasonstarted in Belize) and the processorswere having to hold back more pro­duct than they had space for. Thepreviously active trade in dried conchsto Haiti and the Bahamas is now vir­tually nonexistent, due to the greaterprofit associated with the export offrozen product to the United States.

Florida

Queen conch stocks occur along theAtlantic side of the Florida Keysnorth to the Palm Beach vicinity.They are occasionally seen along thelower southwest coast of Florida. Insouth Florida, queen conch is popu­lar, and large quantities are used infritters, salads, chowders, and fried assteaks. Highest recorded meat pro-

duction was 25,503 kg (56,356 pounds)in 19661

• However, in recent years,often only ten kilograms have beenlanded, the result of harvestingrestrictions imposed in 1971 due toconcern over declining stocks (there isa limit of 10 queen conch per personper day6).

Conch meat imports through Miamiare handled for distribution to retailoutlets by approximately 24 whole­salers. Recent (November 1980) retailprices in south Florida, are commonly$7.15-$8.13/kg ($3.25-$3.65/pound)for cleaned, frozen meat. Two yearsago retail prices at the same storessurveyed in 1980 ranged from $4.60 to$5.50/kg ($2.10 to $2.50/pound).Because of these high prices, harvest­ing restrictions are occasionallyignored and an undocumentedamount of conch meat is sold byfishermen directly to restaurants.

Although strict harvesting restric­tions have essentially eliminated com­mercial fishing, an undeterminednumber of conchs are harvested bysport divers. Conspicuous and easy tocatch, the queen conch attracts the in­terest of even the most novice diverand is considered a prized souvenir. Inview of its popularity in local seafooddishes and the fact that well over amillion tourists visit the Florida Keysyearly, the recreational catch mayindeed be considerable.

Venezuela

There used to be small numbers ofconchs in some areas of the narrowVenezuelan shelf not excessively in­fluenced by wave action and therunoff of rivers (such as Puerto Santo,Puerto Cabello, and San Juan de LosCayos). These have been virtuallyeliminated by overfishing. Someconchs are still available in shallowwaters around Los Testigos, LosFrailes, La Blanquilla, and La Tor­tuga. In La Orchila the conch popula­tions are still extensive due to the fact

'Summary of commercial marine landings.Rorida Department of Natural Resources,Tallahassee, Ra.'Rorida State Statutes, 370.113.

9

that the island is a military zone andthe only fishing permitted is for sportby base residents and visitors. LosRoques and Las Aves de Barlovento ySotavento still have extensive conchresources, in spite of heavy fishingpressure during the 10 years ending in1974. Conchs are also present atMiniscule Aves (Bird) Island, but nowonly at depths :>25m (:>85 feet) wherethey cannot be reached by free divers.

Venezuelan production droppedfrom an estimated 180,000 kg(396,000 pounds) of conch meat in1972 to 10,000 kg (22,000 pounds) in1975 (Fig. 3), mainly due to a closedseason and licensing of conchfishermen imposed by the NationalFisheries Office. Still, much poachingoccurs, especially in the isolated LasAves Islands, from whence the catchescan easily be carried directly to eagermarkets in Bonaire and Curacao. Thereported catch for 1978 was 5,363 kg(11,800 pounds), but the actual figureprobably would surpass 20,000 kg(44,000 pounds). The price in the LaGuaira market in July 1979 wasUS $3.75/kg (US$1.69/pound).

By placing timely controls on theconch fishery, Venezuela has suc­ceeded in maintaining the naturalstocks in the Orchilla, Los Roques,and the two Las Aves archipelagos.However, the pressure is intense, evenwhen the controls are working, andthe conch populations could be vir­tually destroyed in a very short periodof time if the controls were relaxed.

MaricuIture

Because of increasing economic im­portance and concurrent reports ofoverfishing, the technical andeconomic feasibility of conchmariculture has attracted the atten­tion of several investigators (Berg,1976; Brownell et al., 1977; Brownell,1977). These researchers have suc­ceeded in raising conch from eggsthrough metamorphosis and haveachieved normal growth and develop­ment with the resulting juveniles.

D'Asaro (1965) was the first toexamine and describe queen conchlarval development but was unable torear larvae through metamorphosis,

10

mainly due to nutritional limitations.Berg (1976) reported on growth of thequeen conch and potential formariculture.

Optimum larval density of 10 veli­gers/liter was reported by Brownell(1977) in a system of little or no aera­tion, inefficient removal of metabolicwastes, and a purely random assort­ment of food organisms. Larvae wereraised on natural cultures ofphytoplankton in large fiberglasstanks and aquaria with coarselyfiltered, untreated seawater at aremote island research station. Filmsof algae coating the tanks and cover­ing flat stones collected from the in­tertidal zone were utilized as foodsources for juvenile conchs, whichgrew in length at a rate of 0.2-0.3mm/day. Brownell (1977) also notedthat under conditions of abundantfood and absence of predators,juvenile conchs fed actively both dayand night.

Even though these studies havedemonstrated that queen conchs canbe raised in captivity, considerablework still needs to be done before theproper techniques for conch culturecan be defined. Once the technicalpracticality is demonstrated and conchscan be consistently raised in a hatcherysituation, it still will have to be deter­mined if mariculture is economicallyand environmentally feasible, eitherunder intensive culture or for reseedingof depleted conch grounds.

Current and Proposed Research

In recent years, several researchers,particularly in Belize, Turks andCaicos, and Grenada, have studiedhabitat, food preferences, and migra­tion behavior of queen conchs:> 7 cm(:>2.7 inches) in length with theobjectives of defining optimum en­vironmental conditions, fishingpressure, and the potential forrecuperation of overfished stocks.Such information is essential for help­ing local governments to establisheffective management programs andfor determining if conchs can be"farmed" in certain natural areas.Results of these studies have so farbeen inconclusive, due to the follow-

ing difficulties:I) Characteristic habitats are hard

to define and even harder to mapbecause the vegetation and bottomtype undergo seasonal variations andthe conch's preferences change as well.

2) Observation of conch densitiesand movements is limited by theanimals' burying tendencies, unpre­dictable migrations, and periodic con­centrations in deep water that arehard to survey.

3) Fishing activities cannot be con­trolled, since local fisheries depart­ments throughout the Caribbean havelittle or no enforcement or record­keeping personnel; besides, fishermenare always reluctant to specify wherethey get their conchs.

The first comprehensive researchon conchs was carried out by Randall(1964) in the Virgin Islands. Soonafter, a basic conch fishery researchprogram was initiated by the BelizeFisheries Department. Studies onstock density, length frequencies,distribution, harvesting rates, andlandings have been carried out fairlyregularly there since 1973. A new, ex­panded research project began inOctober 1980, primarily to study thebiology of the species as it relates topractical considerations of productiv­ity, growth rate, and increasing sus­tainable yields. The work is beingcarried out by the Belize FisheryDepartment with support from theCanadian International DevelopmentResearch Centre".

The PRIDE (Protection of Reefsand Islands from Degradation andExploration) Foundation at Pine Cayin the Caicos Islands is carrying outresearch on the rearing of conch larvae,the behavior and growth of subadultconchs in various types of enclosures,plus continuation of earlier work(Hesse, 1979) on conch ecology as itrelates to fisheries problems.

PRIDE currently emphasizes mari­culture research through two mainapproaches: Fundamental work at the

'H. Allsopp, Canadian International Develop­ment Research Centre, Vancouver, Canada,pers. commun.

Marine Fisheries Review

wind-powered Pine Cay laboratoryusing filtered ocean water and con­trolled monocultures of phytoplanktonplus a joint effort with the New YorkZoological Society's Osborn Labora­tory at the New York Aquarium usingan established larval culture andmonitoring facility. Both approacheshave yielded some success in the rear­ing of small numbers of queen conchlarvae. Much of this work is supportedby the Griffis Foundation.

Environmental Research Projects,Inc. 8 (ERF) of Grenada has carriedout field studies of conchs at Carricousince 1977 as part of a broad reefecology and fisheries developmentprogram. In 1980 the ERF staff alsodid some larvae culture experiments.With primarily local people doing theresearch, ERF is searching for bettersources of food and more effectiveholding systems for laboratory-rearedlarvae, studying the growth rates andfeeding habits of juveniles under ex­tensive culture conditions, and search­ing for natural nursery grounds ofearly juveniles. Most of this work,plus some of the PRIDE field work, issupported by the Rockefeller BrothersFund.

A major research and developmenteffort with emphasis on mariculturewas planned by the U.S. NationalMarine Fisheries Service in collabora­tion with the University and theGovernment of Puerto Rico, plussome regional support from the FAOWECAF fisheries program. So far,the desired funding has not been ac­quired, but a preliminary effort wasinitiated in Puerto Rico with somesupport from the island's governmentand from the NMFS AquacultureProgram operating out of theGalveston, Tex., laboratory.

Three major proposals for conchresearch emphasizing mariculturehave been submitted to Sea Grant(NOAA) since 1978. All were rejectedfor numerous reasons, the most im­portant one being that there still is no

'Mention of trade names or commercial firmsdoes not imply endorsement by the NationalMarine Fisheries Service, NOAA.

July 1981, 43(7)

clear indication that conch productioncan be increased through mariculture.

Another joint program for conchresearch was established in early 1980by the Wallace Groves AquacultureFoundation and the Rosenstiel Schoolof Marine and Atmospheric Sciences(University of Miami). Field studiesare being conducted on the growthand feeding of juvenile conchs (pri­marily 1-2 years old) at the Founda­tion's facilities in the Bahama Islands.Larval rearing is being carried out atan established molluscan culturelaboratory at the University ofMiami, to the specific culture condi­tions required which will eventuallylead to hatchery-scale rearing.

Conclusions

Increased demand for conch hasresulted in rapid expansion of fishingeffort to the point where overfishingis now occurring. It is unlikely thatcurrent production levels can bemaintained unless: I) Currently inten­sively fished stocks can be managed tostabilize their presently falling levelsof production; 2) conch cultureand/or subsequent stocking prove tobe useful for increasing production inoverfished areas; and 3) new fishingareas can be located and utilized.

Due to rapid and severe declines inseveral major conch fisheries, anumber of management regulationsand export restrictions aimed atpreserving the resource have been im­plemented by several countries. Theseinclude: Closed season (Belize),minimum size (Belize), requirementthat a portion of the catch be reservedfor local consumption (Belize),establishment of sanctuaries (Vene­zuela), daily catch quotas (Florida),and the prohibition of export of un­processed product (Bahamas).

However, we believe that in somecases where queen conch stocks areclearly in peril, conch fishing shouldbe terminated until adequate stockassessements can be made and soundmanagement plans developed. Unfor­tunately, lack of biological informa­tion, and inadequate enforcement andrecordkeeping personnel in localfisheries departments throughout the

Caribbean, hamper development of acomprehensive management strategy.

Mariculture and/or stocking is apossible alternative for increasing ormaintaining production. Conch larvaehave been reared in the laboratorythrough metamorphosis. However,larval culture techniques suitable forestablishment of pilot scale hatcheriesare not yet available.

Existing research programs shouldbe expanded enough to accuratelyevaluate the feasibility of both inten­sive and extensive mariculture prac­tices. If it can be shown that it ispossible to raise conchs consistentlyunder controlled conditions with lowcapital investment, small hatcheriescould be established at key locations,and local residents could be trained tooperate them.

Because of the importance of thequeen conch as both a source of foodand money, it is important thatsignificant efforts be made to save theresource. It is imperative that there beclose cooperation and coordinationamong all appropriate research andmanagement groups.

Note Added in Proof

In January 1981 the WallaceGroves Aquaculture Foundationsponsored a queen conch fisheries andmariculture meeting in Freeport,Bahamas, to bring together conchbiologists and fishery managers andreview conch fisheries, biology, andlarvae culture, and define futureresearch needs. Although recent suc­cesses with rearing conch larvaethrough metamorphosis were reported,more work is still needed to properlyunderstand larval nutrition, triggeringmechanisms for larval metamor­phosis, and maximum rearing densi­ties. At this writing, limited publica­tion of the proceedings is anticipated.

Literature Cited

Adams, J. E. 1970. Conch fishing industry ofUnion Island, Grenadines, West Indies. J.Trop. Sci. 12:279-288.

Alcolado, P. M. 1976. Crecimiento, variacionesmorfologicas de la concha y algunos datosbiologicos del cobo Strombus gigas L.(Mollusca, Mesogastropoda). Serie Oceano­logica 34, 36 p. Academia de Ciencias deCuba.

II

Berg, C. J., Jr. 1975. Behavior and ecology ofconch (Superfamily Strombacea) on a deepsubtidal algal plain. Bull. Mar. Sci.25:307-317.

_---,--__. 1976. Growth of the queen conchSlrombus gigas, with a discussion of thepracticality of its mariculture. Mar. BioI.(Berl.) 34:191-199.

Blakesley, H. L. 1977. A contribution to thefisheries and biology of the queen conch,Slrombus gigas L., in Belize. Abstract ofpaper presented at American FisheriesSociety, 107th Annual Meeting, Vancouver,B.C., September 15-17, 1977.

Boss, K. J. 1971. Conchs. In F. E. Firth (editor),The encyclopedia of marine resources, p.135-140. Van Nostrand Reinhold, N.Y.

Brownell, W. N. 1977. Reproduction, laboratoryculture, and growth of Slrombus gigas, S.coslalus and S. pugilus in Los Roques,Venezuela. Bull. Mar. Sci. 27:668-680.

_----,-_-,-, C. J. Berg, Jr., and K. C. Haines.1977. Fisheries and aquaculture of the conch,Slrombus gigas in the Caribbean. In H. B.Stewart, Jr. (editor), Cooperative investiga­tions of the Caribbean and adjacent regions,Caracas, Venezuela, 12-16 July 1976, p.59-69. FAO Fish. Rep. 200.

D'Asaro, C. N. 1%5. Organogenesis, develop­ment, and metamorphosis in the queenconch, Slrombus gigas, with notes on breed­ing habits. Bull. Mar. Sci. 15:359-416.

Doran, E. 1958. The Caicos conch trade. Geogr.Rev. 48:388-401.

Gunter, G. 1971. The molluscan resources of theGulf of Mexico. FAO Fish. Rep. 1971(2):111-118.

Hesse, C. 0., and K. O. Hesse. 1977. Conch indus­try in the Turks and Caicos Islands. Under­water Nat. 10(3): 4-9.

Hesse, K. O. 1979. Movement and migration ofthe queen conch, Slrombusgigas, in the Turksand Caicos Islands. Bull. Mar. Sci. 29:303-311.

Menzel, R. W. I%9. The possibility of molluscan

12

mariculture in the Caribbean. FAO Fish. Rep.1971(1): 156.

__-=-:-_. 1971. Possibilities of molluscancultivation in the Caribbean. FAO Fish. Rep.1971(2):183-200.

Parker, G. H. 1922. The leaping of the stromb(Slrombus gigas Linn.). J. Exp. ZooI.36:205-209.

Randall, J. E. 1964. Contributions to the biologyof the the queen conch Slrombus gigas.Bull. Mar. Sci. Gulf Caribb. 14:246-295.

Robertson, R. 1959. Observations of the spawnand veligers of conchs (Slrombus) in theBahamas. Proc. Malacol. Soc. Lond.33: 164-170.

_---,_-.,-. 1%1. The feeding of Slrombus andrelated herbivorous marine gastropods, witha review and field observations. NotulaeNaturae 343:1-9.

Warmke, G. L., and R. T. Abbott. I%1. Carib­bean seashells. Livingston Pub!. Co.,Narberth, Pa., 348 p.

Yonge, C. M. 1932. On the size attained by thecrystalline style in Tridacna and Strombus.Proc. Malacol. Soc. Lond. 20:44-45.

Selected References

Abbott, R. T. 1974. American seashells. VanNostrand Reinhold, N.Y., 663 p.

Berg, C. J., Jr. 1972. Ontogeny of the behaviorof Slrombus maculalus (Gastropoda:Strombidae). Am. Zool. 12:427-443.

____. 1974. A comparative ethologicalstudy of strombid gastropods. Behavior51 :274-322.

Brownell, W. N., and C. J. Berg, Jr. 1978.Conchs in the Caribbean: A sustainableresource? Sea Front. 24: 178-185.

Clench, W. J., and R. T. Abbott. 1941. Thegenus Strombus in the western Atlantic.Johnsonia 1(1):1-15.

Darcy, G. H. In press. Annotated bibliographyof the conch genus Slrombus (Gastropoda,Strombidae) in the western Atlantic Ocean.

U.S. Oep. Commer., NOAA Tech. Rep.NMFS SSRF.

D'Asaro, C. N. 1970. Egg capsules of proso­branch mollusks from South Florida and theBahamas and notes on spawning in thelaboratory. Bull. Mar. Sci. 20:414-440.

Flores, C. C. 1964. Notes on the geographicdistribution and importance of Slrombusgigas Linnaeus 1758 (Mollusca:Mesogastro­pada) in the coastal waters of Venezuela.Lagena 3:32-34.

__---,--_. 1964. Contribution to the knowl­edge of the genus Slrombus Linneaus 1758(Mollusca: Mesogastropoda) in the coastalwaters of Venezuela. Sociedad de CienciasNaturales La Salle, Memorias 24:261-276.

Hughes, H. P. I. 1976. Structure and regenera­tion of the eyes of strombid gastropods. CellTissue Res. 171:259-271.

Little, C. 1965. Notes on the anatomy of thequeen conch, Slrombus gigas. Bull. Mar.Sci. 15:338-358.

___---,--. 1967. Ionic regulation in the queenconch, Strombus gigas (Gastropoda, Proso­branchia). J. Exp. BioI. 46:459-474.

Percharde, P. O. 1968. Notes on distributionand underwater observations on themolluscan genus Slrombus as found in thewaters of Trinidad and Tobago. Caribb. J.Sci. 8:47-55.

_---,--__. 1970. Further underwater observa­tions on the molluscan genus SlrombusLinne as found in the waters of Trinidadand Tobago. Caribb. J. Sci. 10:73-81.

Randall, J. E. 1%3. Monarch of the grassflats. Sea Front. 9: 160-167.

__----,-_. 1964. The habits of the queenconch. Sea Front. 10:230-239.

Sangster, A. W., S. E. Thomas, and N. L.Tingling. 1975. Fish attractants from marineinvertebrates. Arcamine from Area zebraand strombine from Strombus gigas.Tetrahedron 31: 1135-1137.

Verrill, A. H. 1948. The status of Strombussamba Clench. Nautilus 62: 1-3.

Marine Fisheries Review