Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Florida)

Home , Gulf flounder, Lagodon, Spot (fish), Starry flounder, Yellowtail flounder

-AD-AIBI 588 SPECIES PROFILES LIFE HISTORIES AND ENVIRONMENTAL 1/1 I REQUIREMENTS OF COASTAL.. (U) FLORIDA STATE MUSEUM I GAINESVILLE FL C R GILBERT JUL 86 FWS-82/11. 54 UNWScLMSIFIEDF/G /3 NL MICROCOPY RESOLUTION TEST CHART NATIOANUGM Of STANDARDS-1163-A

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Species Profiles: Life Histories and D~rlC Environmental Requirements of Coastal FishesEL TEf and Invertebrates (South Florida)JU1998 E SOUTHERN, GULF, AND SUMMER FLO NDERS

Coastal Ecology Group Fish and Wildlife Service Waterways Experiment Station U.S. Department of the Interior U.S. Army Corps of Engineers

IN__=&OWL _ 87 041, 0; Biological Report 82(11.54) TR EL-82-4 July 1986

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Florida)

SOUTHERN, GULF, AND SUIJER FLOUNDERS

Carter R. Gilbert Florida State Museum University of Florida Gainesville, FL 32611

Project Manager Larry Shanks Project Officer John Parsons National Wetlands Research Center U.S. Fish and Wildlife Service 1010 Gause Boulevard Slidell, LA 70458 Performed for Coastal Ecology Group U.S. Army Corps of Engineers Waterways Experiment Station Vicksburg, MS 39180 and

National Wetlands Research Center Research and Development Fish and Wildlife Service U.S. Department of the Interior Washington, DC 20240

- I& I This series should be referenced as follows: U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life histories and environmental requirements of coast-T fishes and invertebrates. U.S. Fish Wildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL- 82-4. This profile can be cited as follows:

Gilbert, C.R. 1986. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (South Florida)--southern, gulf, and sumer flounders. U.S. Fish Wildl. Serv. Biol. Rep. 82(11.54). U.S. A/W Corps of Engineers, TR EL-82-4. 27 pp.

-dn. PREFACE This species profile is one of a series on coastal aquatic organisms, principally fish, of sport, commercial, or ecological importance. The profiles ore designed to provide coastal managers, engineers, and biologists with a brief comprehensive sketch of the biological characteristics and environmental requirements of the species and to describe how populations of the species may be expected to react to environmental changes caused by coastal development. Each profile has sections on taxonomy, life history, ecological role, environmental requirements, and economic importance, if applicable. A three-ring binder is used for this series so that new profiles can be a d as they are prepared. This project is jointly planned and financed by the U. Army Corps of Engineers and the U.S. Fish and Wildlife Service.

Suggestions or questions regarding this report s ould be directed to one of the following addresses. 0 Information Transfer Specialist - ' - - National Wetlands Research Center U.S. Fish and Wildlife Service NASA-Slidell Computer Complex 1010 Gause Boulevard Slidell, LA 70458 or U.S. Army Engineer Waterways Experiment Station Attention: WESER-C Post Office Box 631 Vicksburg, MS 39180 Acoession For NTIS GRA&I DTIC TAB Unamounced Justifioaton

Diltributlon/

Availabilityr Codes Avail and/or DIst SPecial f S- CWVERSION TABLE

Metric to U.S. Customary Nltily ft To Obtain millimeters (me 0.03937 inches centimeters (am) 0.3937 inches meters (i) 3.281 feet kilometers (ion) 0.6214 miles 2 square meters (m 2 10.76 square feet square kilometers (ion2) 0.3861 square miles hectares (ha) 2.471 acres liters (1) 0.2642 gallons cubic meters (m3) 35.31 cubic feet cubic meters 0.0008110 acre-feet milligrais (mg) 0.00003527 ounces grams (g) 0.03527 ounces kilograms (k9) 2.205 pounds metric tons (t) 2205.0 pounds metric tons 1.102 short tons kilocalories (kcal) 3.968 British thermal units Celsius degrees 1.8(-C) + 32 Fahrenheit degrees

U.S. Customary to Metric inches 25.40 millimeters inches 2.54 centimeters feet (ft) 0.3048 meters fathofs 1.829 meters miles (ml) 1.609 kil meters nautical miles (rim) 1.852 kilometers square feet (ft2) 0.0929 square meters acres 2 0.4047 hectares square miles Cmi 2) 2.590 square kilometers gallons (gal) 3.785 liters cubic feet (ft3) 0.02831 cubic meters acre-feet 1233.0 cubic meters ounces (oz) 28.35 grams pounds (lb) 0.4536 kilograms short tons (ton) 0.9072 metric tons British thermal units (Btu) 0.2520 kilocalories

Fahrenheit degrees 0.5556(°F - 32) Celsius degrees

.~~~~ .R ~~~~~ '' r Ano IMI,,lr'w CONT ENTS

Page P'REFACE ...... iii CONVERSION TABLE...... iv FIGURES...... vi ACKNOWLEDGMENTS ...... vii NOMENCLATURE/TAXONOMY/RANGE...... 1 MORPHOLOGY/IDENTIFICATION AIDS...... 2 Adults...... 2 Southern Flounder...... 2 Gulf Flounder ...... 2 Summer Flounder...... 6 Postlarvae...... 6 REASON FOR INCLUSION IN SERIES...... 6 LIFE HISTORY...... 7 Reproduction ...... 7 Early Development Stages ...... 9 Migration and Movement of Adults...... 11 Subpopulations...... 11 GROWTH CHARACTERISTICS ...... 12 ECOLOGICAL ROLE...... 14 Food and Feeding ...... 14 ENVIRONMENTAL REQUIREMENTS...... 16 Substrate ...... 16 Salinity ...... 17 Temperature...... 18 Vegetation ...... 18 Dissolved oxygen ...... 19 FISHERY...... 19 Quality and Value of Commercial Fishery ...... 19 Sport Fishery...... 20 LITERATURE CITED ...... ;...... 23

v FIGURES

1 Southern flounder (Parelichthys lethostima ...... 1

2 Gulf flounder (Paralichths aiblautta) ...... 1

3 Summer flounder (Paralichthws dentatus) ...... 1 4 Areas of greatest abundance of southern flounder in south Florida ...... 3 5 Areas of greatest abundance of gulf flounder in south Florida ...... 4 6 Aras of greatest abundance of summer flounder In south Florida...... 5 7 Late postlarval pigmantation of summer flounder...... 6 a Late postlarval pigmentation of southern flounder ...... 6 9 Egg development and yolk-sac larva of sumer flounder ...... 120 10 Yolk-sac larva to larval stages of summer flounder...... 120 22 Larval stages of summer flounder...... 1 12 Length-weight relationship for summer flounder ...... 13 13 Length-weight relationshiip for southern flounder...... 14 14 Length-weight relationship for gulf flounder ...... 15 15 Percentage of volume and percentage of occurrence of food items in seasonal diet of young summer flounder and southern flounder from Pamlico Sound, North Carolina ...... 16

vi ACKNOWLEDGMENTS I wish to thank Ms. Rosemarie Mulholland, Florida Department of Natural Resources, Clermont, Florida, for providing access to information she had com- piled on the southern and gulf flounders while a graduate student at the Uni- versity of Florida. I also wish to thank Mr. George H. Burgess, Florida State Museum, University of Florida, Gainesville, for the loan of various reference items used in preparation of this report. I wish to express my appreciation to the journal C for permission to reproduce Figures 7 and 8, and to Estuaries for permission to reprint Figure 15.

vii "V uir 1. S~outhrn~ flouner '-Flgure 2. Gulf flounder f'iralichthys

1974; rdan from Ginsburg 1952.pn rg 52).

Fgure 3. 0 Sume r flounderl varadentatus (Powell 1974; redrawn from Gfinsbur 2).

SOUTHERN, GULF, AND SUMM~ER FLOUNDERS

NOMENCLATURE/TAXONOMY/RANGE Scientific name...... Paralichthys dentatus (Linnaeus) ...... Summer Scientific name...... Paraichthys flounder common(Figure 3)name OMENCLATUREPreferred- and Gilbrt Other cmn names.....American ScietiiehsimaPrf~id~non Jordan nme...ouhrnubot; -o-ng-75oothed flounder; Fourige jcommnon flounder; flounder, fluke; Other common names -..~Mud flounder, flounder of New Yrk lu(New York); southern large flounder; doormat; plaice (New York, ka's4achusetts); flondr;flke- halibut) -turbot (Massachusts); ltih (Long IslanA Yorkj Chepsa eaZ: Scientific name...... Paralichthys Ba 1; fqlken haibut-Vaa 1ut, aliut Jordan and Gilbr 2 r cck oe Island) Preferredcommon name...... Gulf flounder (Figure 2) Class ...... 7 Osteichthyes Other conmmon names Sand flounder, Order...... Pleuronectiformes flounder, fluke Family ...... Bothldae

2L4& ' j Geographic ranges: ally down to 183 m; but occurs at greater average depths to the Southern flounder: Occurs from south. Rarely enters waters of Albemarle Sound, North Carolina, reduced salinities, and never south to Loxahatchee River, on recorded from freshwater. lower east coast of Florida; it is absent from there south and around tip of peninsular Florida, but MORPHOLOGY/IDENTIFICATION AIDS occurs in Caloosahatchee River Estuary, on southwest coast of Florida, and from there around the Adults Gulf of Mexico to northern Mexico (Hoese and Moore 1977; Manooch All species of Paralichthys are 1984) (Figure 4). Most common in relatively large, robust, darkish, western half of the Gulf of Mex- lefteyed flatfishes with large mouths ico. Generally occupies water of (upper Jaw extending to or beyond lesser average depth than either posterior margin of eye) and well- the gulf flounder or the summer developed teeth. The bases of both flounder. It is common to depths pelvic fins are short and neither of 47 m (Nall 1979); the greatest extends forward to the urohyal bone. confirmed depth is about 61 m (Stokes 1977). Frequently occurs in water of low salinity or even Southern Flounder freshwater (Ross 1980). Gulf flounder: Ranges continuously Diffuse dark spots and blotches in coastal waters from Cape Look- on pigmented side of body, ocellated out, North Carolina, to Corpus spots absent (Figure 1); gill rakers Christi, Texas (Figure 5), usually on lower limb of outer arch 8-11 in waters less than 92 m deep, but (usually 9-10); anal rays 63-73 occasionally as deep as 128 m (usually 65-71); dorsal rays 80-95 (Ginsburg 1952; Gutherz 1967). Has (usually 84-92); scales in straight occasionally been recorded from portion of lateral line 52-69 extreme western Bahamas (Bohlke and (usually 56-64); size relatively Chaplin 1968), and is most common large: attains a maximum standard in eastern half of Gulf of Mexico length (distance from snout to base and along eastern coast of Florida. of tail) of 660 mm and a weight of Rarely enters waters of reduced over 3 kg (Nall 1979). silinities, and never enters freshwater. Summer flounder: Ranges from Gulf of Gulf Flounder Maine (Bigelow and Schroeder 1953) and occasionally Nova Scotia (Leim Three small, usually conspicuous, and Scott 1966) south along Atlan- ocellated spots on pigmented side of tic coast at least to Sebastian body in a triangular pattern, with Inlet, on southeast coast of Flor- the apex of the triangle pointing ida (Figure 6). Reports of occur- posteriorly and the posteriormost rence in Gulf of Mexico (Poole spot situated astride lateral line 1962; Powell 1974; Rogers and Van (Figure 2); gill rakers on lower limb Den Avyle 1983) are in error (Gins- of outer arch 9-12 (usually 10-11); burg 1952; Gutherz 1967; Topp and anal rays 53-63 (usually 56-61); Hoff 1972; Hoese and Moore 1977; dorsal rays 71-85 (usually 75-81); Wilk et al. 1980; Manooch 1984). scales in straight portion of lateral Most common between Cape Cod and line 47-60 (usually 52-57); size Chesapeake Bay, usually in waters relatively small: attains a maximum less than 37 m deep, and occasion- standard length (SL) of about 420 mm 4 2 6A LAINTE

ICEECHOBEE PALM BEACH

GULF OF FLORIDA*~ MEXICO

THOUSAND ISLANDS

FLORIDA SA Y%

MILES

0 ~ s - 1000 -

0 so I;0 KILOME TERS

Figure 4. Areas of greatest abundance of southern flounder in south Florida.

3 .* .* TLANTIC OCEAN

TAMPA

ST. PETERSBURG

KCEECNOBEE FMMBEACH

......

*MIAM

......

MILES

so5 100

0 so 100 KILOMETERS

Figure 5. Areas of greatest abundance of gulf flounder in south Florida.

4 ...... ------V.I OCEAN

......

0 TAMPA

ST. PETERSBURG

ICEECHOSEE PALM BEACH

GULF OF FLORIDA MEXICO

CAPE ROMANO

THOUSAND ISLANDS AREA

FL ORIDA SA Y.*

MILE S

0 50 100

0 so 100 KILOMETERS

Figure 6. Areas of greatest abundance of summner flounder in south Florida. and a weight of about 1.7 kg (Nal 1979). Vick (1964) suggested a maximum length of over 700 -.

Sumer Flounder I MM Five small ocellated spots usually present on pigmented side of Figure 7. Late postlarval pigmenta- body (becoming obscure in larger tion of suer flounder (Deubler specimens), with the first two and 1958). last two situated on the lateral line (Figure 3); gill rakers on lower limb of outer arch 13-18 (usually 15 or more); anal rays 61-73 (usually 66-70); dorsal rays 80-96 (usually 85-90); scales in straight portion of lateral line 56-76 (usually - 62-70); size relatively large: " attains a maximum standard length (SL) of about 700 mm and a weight of I M over 4.4 kg (Powell 1974). Figure 8. Late postlarval pigmentation of southern flounder (Deubler Post1 arvae 1958). Postlarvae (i.e., individuals that have metamorphosed into an adult-like form) of the summer rays is the most diagnostic charac- flounder can be distinguished from ter, but number of dorsal rays will those of the southern and gulf also separate most spermens (see flounders by pigmentation pattern sumary of adult charactt.istics). (Deubler 1958). Summer flounder at 9-15 m SL have a well-defined band of black pigment along the border of the anterior four-fifths of the dorsal fin and along the anterior two- REASON FOR INCLUSION IN SERIES thirds of the anal fin (Figure 7); pigment is lacking in these areas in both the southern and gulf flounders The three species of Paralichthys (Figure 8). Vertebral differences are important components of both the are also useful for separating post- comercial and sport fishery catches, larval summer flounder from the other but since they are combined in catch two species: P. dentatus has 40-42 statistics under the collective name total vertebrae (usually 41), and "fluke" (BCF 1964b-1968b; NNFS 196b- the other two species have 36-38, 198b), the exact importance of each usually 37. Gill rakers are not species cannot be ascertained. In sufficiently developed at this size general, however, the summer flounder to be of aid in identification, is considered the most important of Postlarval southern and gulf floun- the three species because of its ders are difficult to separate at prominence in the sport and commer- small sizes, inasmuch as no pigmen- cial fishery catches on the upper tary differences have been discovered Atlantic coast from Cape Hatteras and vertebral counts for the two spe- northward. Commercial fishery sta- cies are identical. Number of anal tistics from 1964 to 1985 indicate 6 that "fluke" have become an increas- development take place. Appearance ingly more important part of the of juvenile (i.e., late postlarval) comercial catch in terms of both flounders in bays and estuaries dollar value and the amount of fish along the Atlantic coast usually taken. peaks when stratification and tidal exchange ratios are at a yearly maximum. Juveniles may move to the LIFE HISTORY surface at night and then be carried by flood tides into tidal creeks (Weinstein et al. 1980). In North Of the three species, the summer Carolina, newly metamorphosed flounder has received the greatest Juvenile Paralichths spp. were attention with regard to studies of captured from December through April its life history and ecology; Powell in estuarine nursery areas (Powell (1974) and Rogers and Van Den Avyle and Schwartz 1977). Juveniles (1983) have provided the most com- remain in nursery areas until sexual plete sumaries. Topp and Hoff maturity is reached, and do not move (1972) summarized biological data into offshore waters until just for the gulf flounder. Stokes (1977) prior to spawning (Powell and studied the life histories of both Schwartz 1977). the gulf and southern flounders in the Aransas Bay area of Texas, and Controversy exists with regard to Nall (1979) studied age and growth age at which sexual maturity is of these two species in the northern reached, primarily because of Gulf of Mexico. Powell (1974), in differences in interpretation of his study of the summer flounder .in aging techniques. Stokes (1977) and North Carolina, also included consid- Manooch (1984) indicated that both erable ecological data on the southern and gulf flounders attain southern flounder and limited data sexual maturity at 2 years of age; for the gulf flounder. Powell (1974) reached a similar conclusion for the southern flounder. Powell (1974) and Manooch (1984) also Reproduction stated that the summer flounder does not achieve sexual maturity until it Reproductive strategies appear to is 3 years old. However, Nall (1979) be similar for the three species of reported that the southern flounder Paralichthys. Adults of each species does not reach sexual maturity until spend most of the year in bays and at least 4 years of age, and that estuaries, emigrating into deeper sexual maturity of all individuals offshore waters during fall and was not achieved until they were winter as temperatures drop. more than 6 years old. Spawning occurs at these times; ripe individuals have been collected from Stokes (1977) reported adult September to mid-April (Bigelow and southern flounder leaving Aransas Schroeder 1953; Smith 1973) at Bay, Texas, for the Gulf of Mexico depths ranging from 20 to 136 m. from mid-October to mid-December. Spawning begins earlier at more Emigration peaked during mid-November northerly latitudes (Smith 1973), and seemed to be correlated with a and occurs progressively later as sudden drop (4-50C) in temperature. one proceeds southward. Eggs and Males appeared to leave somewhat newly hatched larvae float at or earlier than females (Simmons and near the surface, and the developing Hoese 1959; Stokes 1977). individuals are carried inshore by winds and currents into nursery Southern flounder spawn from areas, where further growth and September to April, although peak

7 activity is from November to January gonads have been collected at depths (Gunter 1945). Spawning apparently of 20-40 m in the eastern Gulf of occurs at depths of 20-60 m (Benson Mexico from November through February 1982). Arnold et al. (1977), who (Topp and Hoff 1972). observed summer flounder spawning in the laboratory, reported that Larval gulf flounder appear in spawning females swam upward in the the eastern Gulf of Mexico from water column and released their eggs, December to early March (Topp and which were immediately fertilized by Hoff 1972), and juveniles are seen a single attending male. in bays and estuaries in January throughout their range, with peak Immigration of juvenile southern movement usually occurring in early flounder into Texas bays begins in February (Reid 1954; Springer and January and increases rapidly into Woodburn 1960; Tagatz and Dudley February, after which there is a 1961; Stokes 1977). Juvenile gulf gradual increase in numbers of flounder, like southern flounder, individuals throughout the spring; begin immigrating into Aransas Bay abundance peaks during mid-summer when water temperatures reach 14-160C (Stokes 1977). Immigration begins (Stokes 1977). Topp and Hoff (1972) when the average water temperature reported spent females in Tampa Bay is as low as 13.80C, and peaks when in February. average water temperature is between 16.0 and 16.20C. Adult summer No fecundity data are available flounder return to Texas bays and for the gulf flounder. Gonadal estuaries from February to April, examination by Nall (1979) indicated and remain there until the following that females mature at sizes as small fall. as 145 mm SL. Manooch (1984) stated that sexual maturity in this species I The only available figures on is attained at two years of age. He fecundity are those of Arnold et al. also indicated the average total (1977), who indicated an average of length of two-year-old individuals to 40,000 eggs per female in the 1-3 kg be around 350 mm, and the average weight range. Nall (1979) found length of three-year-olds to be about developing eggs in all female 400 mm. southern flounder over 6 years old, but in only 5-18% of females 4-6 Most information on the summer years old. The smallest maturing flounder is based on studies of female reported by Nall (1979) was populations from Pamlico Sound, North 256 mm SL (308 mm total length [tip Carolina, northward. Smith (1973) of snout to tip of tail]). Manooch observed a seasonal progression in (1984), who indicated that this spawning from north td south. He species becomes sexually mature at 2 found that peak spawning at the years of age, gave the average total northern limits of its range occurred length (TL) of 2 year-old individuals in early September, spawning north of as around 365 mm. Chesapeake Bay peaked in October, and spawning south of Chesapeake Bay Reproduction in the gulf and peaked during November. Bigelow and southern flounders is similar in most Schroeder (1953) reported collection respects. Gulf flounder spawn in the of a ripe female in mid-April off Gulf of Mexico from mid-fall through Nantucket Island, Massachusetts, but mid-winter, and Stokes (1977) this is unusual. During the 1971-72 reported ripe adults leaving Aransas season, spawning did not occur until Bay, Texas, from mid-October through February around Cape Lookout, North December. Spawning evidently occurs Carolina. Powell (1974), on the offshore, and specimens with ripe basis of gonadal development, 8 reported that most sumer flounder in Early Developmental Stages North Carolina waters south of Cape Hatteras spawned from December Balon (1975) defined develop- through February. mental stages as egg, larva, Juvenile, and adult. Transition As is true of the other two from egg to embryo occurs when the species, summer flounder spend the egg membrane ruptures; the embryo warmer months in coastal embayments becomes a larva when the individual and sometimes in nearshore shelf switches from endogenous to exogenous waters, and migrate offshore during feeding; and the larva becomes a the fall as waters cool. Rogers and juvenile upon metamorphosis to an Van Den Avyle (1983) reported adult-like form. Inasmuch as all spawning over a broad depth range three species spawn offshore, the (30-200 m). Individuals move into various life stages are adapted for deeper water near the peak of their development in full-strength sea- gonadal development cycle, with the water. The onset of metamorphosis oldest and largest fish apparently in flatfishes appears to be more moving out first (Morse 1981). The closely related to environmental most important nursery areas are temperature and/or size of the located between Long Island, New individual than to age (Policansky York, and South Carolina (Powell 1982). (1974); the heaviest concentrations are in Virginia and North Carolina Although a detailed description (Poole 1966). Summer flounder less of early developmental stages exists than 280 mm TL are uncommon off New only for the summer flounder (Martin England, which suggests that indi- and Drewry 1978: 157-163), one can viduals found in those waters have assume that the characters given migrated there from the south and apply in large measure to the other that most are about three years old two species as well. Martin and (Lux and Nlchy 1981). Drewry (1978) described the eggs of the summer flounder as "small, Smith (1973) reported that eggs spherical, and transparent ... with found at or near the surface were a rigid shell," and measuring from most common when bottom temperatures 0.90 to 1.13 mm (mean - 1.02 mm). were 12-19 0C. Powell (1974) found The eggs are buoyant (thus, pelagic) the most eggs in North Carolina and contain a single oil globule in waters when bottom temperatures were the yolk (Figure 9). about 150C. Eggs of the summer flounder have Prior to Smith's (1973) study, been observed to hatch in from 2 to 9 it had generally been accepted that days (48 to 212 hrs) under laboratory currents transport larval summer conditions, at temperatures from 210C flounder from the north to major down to 50C (Johns and Howell 1980; nursery areas farther south, but it Johns et al. 1981). Lengths at now appears that, although eggs and hatching were from 2.83 to 3.16 mm larvae may drift with the current, (Johns et al. 1981). Although those this is less important than formerly authors reported hatching at believed, temperatures as low as 50C, they also indicated that temperatures Female summer flounder appear to below 11oC were lethal to larvae reach sexual maturity at 300-330 mm during development. Yolk-sac TL and males at 240-270 mm TL. The absorption (i.e., transition to smallest female examined by Morse larval stage) in this species occurs (1981) was 250 mm TI, and the at about 3.6 mmn, and Johns et al. smallest mature male was 190 mm TL. (1981) indicated that this size is 9 !01111!!i1jC111dO 101M reached approximately 5.7 days after noticeably more pigmented than the hatching at 11.2 0C, or in 2.8 days at right side. At 16 m, individuals 210C. At this point the eyes are have a form and shape resembling the pigmented, the mouth functional, and adult, and pigmentation is almost the digestive tract complete (Figure entirely restricted to the left 10). Hildebrand and Cable (1930) (i.e., eyed) side of the body. At indicated that newly hatched embryos 77 m, the body is completely scaled of "Paralichthys spp." from Beaufort, and has the characteristic form and North arolina (the summer flounder pigmentation of the adult. is the dominant species in that area) are about 2.5 - long. At 7 m the Arnold et al. (1977) reported larvae lose their symmetry and the that eggs of the southern flounder right eye begins to migrate dorsally. hatched at 61 to 76 hrs under Martin and Drewry (1978), however, laboratory conditions. Time at showed that this change in symmetry which transition from embryo to occurs at a slightly larger size larva occurred was not indicated, (ca. 9.5 mm). At 10.5-11 m, the but time required for metamorphosis right eye becomes situated on the to begin in the laboratory was 40 to ridge of the head (Figure 11), the 46 days after hatching (at 8 to 11 body becomes increasingly compressed, m), and this process was completed and the left side of the body is in 50 to 51 days.

.QO.0

C "..." "- -4.S5 UK 3.0.1 m

2.76 UL

Figure 9. Egg development and yolk-. sac larva of summer flounder, from "9.z7 N less than 32 h after fertilization to 75 h after fertilization. Lengths Figure 10. Yolk-sac larva to larval expressed in standard length (SL) or stages of summer flounder: (A) 12 h notochord length (tip of snout to after hatching, (B) 96 h after hatch- end of notochord) (NL) (Martin and ing, and (C-E) subsequent stages Drewry 1978). (Martin and Drewry 1978).

~, i I .,0 Middle Atlantic Bight (i.e., from Cape Hatteras northward) indicated an overall movement of this species toward the northern limits of the < Bight as the fish grow older.

The only published results of tagging studies involving the southern flounder are those by Stokes (1977) from Texas, who reported 28 returns out of a total of 1,298 2 .48L individuals tagged (2.2%) between early 1974 and late 1975. He reported some movement between and within Texas bays, although no consistent patterns were evident. Returns showed movement of from 0 to 18.2 km over periods of 3 to 212 days; the most rapid movement was .1.4,,n 9.3 km in 3 days. One individual tagged in November 1973, in Aransas Bay, was recovered 1 year later 451 to the east. Figure 11. Larval stages of summer km flounder, showing transition of eyes The only tagging study of gulf from symmetrical to asymmetrical flounder was by Stokes (1977), who position (Martin and Drewry 1978). reported no returns out of a total of 33 individuals tagged.

Although the above data seem to Migration and Movement of Adults indicate more extensive movements of the sumner flounder than the other Seasonal inshore-offshore two species, this may be, at least movements of adult Paralichths are in part, a result of the greater related to spawning activities, as number of summer flounder tagged, as discussed earlier. Tagging studies well as the longer period of time of sumer flounder show that latitu- during which studies on the summer dinal movement occurs along the flounder were carried out. Atlantic coast. Of a total of 6,679 individuals tagged off New Jersey during 1960-67, 2 were recaptured Suboopulations south of Cape Hatteras, North Carolina (Murawski 1970). Poole Analysis of morphometric and (1962) reported 1 return from below meristic characters in 1,214 Ca Hatteras out of 5,845 individ- specimens of summer flounder from uals tagged in New York waters New York to central Florida indicate during 1956-59. Lux and Nichy two distinct subpopulations, one in (1961) reported I return (out of the Middle Atlantic Bight north of 2,639) in early 1963 from off Cape Hatteras, North Carolina, and southern Maryland; the individual the other in the South Atlantic had been tagged in New York waters Bight (Wilk et al. 1980). Discrim- the preceding September. Lux and inant analysis coefficients indicate Nichy (1961) and Rogers and Van Den these subpopulations are separable Avyle (IM3), however, said that in at a level of 93%. These results general tagging studies in the are partly confirmed by tagging studies by Poole (1962) and Murawski lic Different investigators (1970), who found little evidence of h:ve "...variously indicated the movement of individuals between first 'annulus' in the summer these two areas, as well as Smith's flounder to form at ages 1I through (1973) studies of distribution VII, indicating that length-at-age patterns of eggs and larvae. Smith information is subject to consider- (1973) had also suggested that the able error" (Rogers and Van Den Avyle subpopulation in the Middle Atlantic 1983). Poole (1961) and Powell Bight could be further subdivided, (1974), working on New York and North with one group occurring in New York Carolina populations, respectively, and New Jersey and the other from determined that the first opaque Delaware Bay to Cape Hatteras; but ring on the otoliths of summer Milk et al. (1980) could neither flounder was a valid first annulus. confirm nor deny this hypothesis on Poole also concluded that the species the basis of their work, attains a maximum age of no more than 5 years, but he did not attempt to There is insufficient data to estimate maximum longevity. Eldridge indicate whether or not distinct (1962), Smith (1969), Daiber and subpopulations of southern and gulf Smith (1969), and Smith and Daiber flounders exist; however, the wide (1977) determined that the first distributional break of the southern distinct opaque ring does not repre- flounder around the tip of peninsular sent the first annulus, and concluded Florida (Figure 4) suggests that that this species lives as long as 8 this is a reasonable possibility, or 9 years. Smith et al. (1981) concluded that estimates of greater longevity are more likely correct. GROWTH CHARACTERISTICS Similar controversy results from the age-growth studies on southern Almost all age-growth studies of flounder by Stokes (1977) and Nall Paralichthys have used otoliths to (1979) on Texas and northern Gulf of deterineage. Analyses of yearly Mexico populations, respectively. size classes, even at small sizes, Stokes concluded that this species have been shown to be of limited lives a maximum of 5 years, as value because of variable individual opposed to the 9 (occasionally 10) growth rates and protracted spawning years projected by Nall (1979). The seasons. Body lengths may be only age-growth studies on the gulf expressed either as standard length flounder were also conducted by or total length. Sometimes method Stokes (1977), who indicated that of measurement is not indicated, they live a maximum of 3 years. although in such cases one can Assuming that Stokes (1977) was usually assume this to be total consistent in his aging techniques length. Since the tail makes up for southern and gulf flounder, one about 17% of the total body length, may presume that the latter species one can substract this percentage, has the shorter life span of the when necessary, to obtain approximate two, although it may be longer than standard length. Sex of individuals that indicated by Stokes. analyzed is not always indicated, despite evidence that Paralichthys tHanooch (1984) summarized age- females reach a larger size than growth data for all three species. sales. He indicated a maximum age of 9 years for the summer flounder, and Controversy exists regarding listed the following average yearly results of various otolith aging total lengths in mm for age groups studies on the species of Para- 1-IX (females only): 215, 288, 377, 12

12I 428, 488, 511, 531, 564, and 597 Anil. mm. These data are comparable to those provided for females of this 44/ species by Eldridge (1962) and Smith and Dater (1977), who gave the following yearly average total lengths (also in m) for age groups W - 0.557 L.mW x 1o-5 I-VII: 170, 250, 332, 377, 415, 446, W -S773U'+30 and 456 mm. As indicated from the --LOGW 4-2M +3.OSSLOGL above, females not only reach a 3 R = 0.9 larger size but also apparently live longer, inasmuch as all individuals examined by Eldridge (1962) that were over 7 years of age were females. In all studies but one it was concluded that females live 1 year longer than males; the exception was reported by Smith (1969), who determined that male summer flounder achieve a maximum age of only 5 years, as opposed to 8 For females. Daiber and Smith (1969) found the respective maximum sizes for female and male summer flounder from Delaware to be 661 and 517 -m TL. " " " - " W" Powell (1974) found that only two individuals from North Carolina (out of a total of 1,029) exceeded 650 m Figure 12. Length-weight relation- TL, with the largest being 750 mm. ship with fitted curve for summer Poole (1966) determined the maximum flounder. Weight expressed in size of females from New York to be grams; length in total length (Powell around 800 m TL and 5.5 kg, and for 1974). males 600 mm TL and 2.2 kg. DeSylva (1965) reported that although this species occasionally reaches 11-13.6 and provided the following average kg, a weight of 7 kg is unusual; he standard lengths in mm (sexes com- indicated that most adults weigh bined) for each year of life approx- between 0.9-2.3 kg. Powell (1974) imate converted (total lengths indi- presented a graph showing length- cated in parentheses): Age 0 63 weight relationships based on 1029 (76), I - 102 (1-2), I - 145.5 specimens (sexes combined) from North (175), III - 190.5 (250), IV - 230.5 Carolina (Figure 12). (278), V - 272 (327), VI - 320 (384), VII - 351.5 (423), VIII - 382 (460). Manooch (1984) indicated life Stokes (1977), in studies of Texas spans of only 5 and 3 years for the populations of the southern flounder, southern and gulf flounder, respec- found differences in size and life tively. This information is in accord span between males and females with, and may partly have been based similar to those reported earlier upon, Stokes' (1977) studies from for the summer flounder. He reported Texas. However, Nall (1979), based that females live up to 5 years and on examination of 152 specimens from reach a total length of up to 620 mm, the northern Gulf of Mexico, calcula- whereas males live only up to 3 years ted a life span of 9 (occasionally and reach a maximum total length of 10) years for the southern flounder, 320 mm. Although Stokes may have 13 underestimated the overall life span with work on the southern flounder, of this species, his data clearly which is much more common in the indicate that females live longer respective study areas (Texas and and attain a larger size than males, the northern Gulf of Mexico); the small number of specimens available The largest individual southern to Nall (33) precluded his attempting flounder (620 - TI) reported by any aging estimates. Stokes (1977) Stokes (1977) is slightly larger concluded, based on a total of 123 than that examined by Hall (1979) specimens, that female and male gulf (493 - SL, or ca. 595 mm TL). flounder live only 3 and 2 years, Ginsburg (1952), however, reported a respectively, and these figures were maximum size for this species of 630 repeated by Manooch (1984). Although m SL (- 762 m TI). Nall (1979) the gulf flounder may live longer weightpresented relationshipsa graph showing based onlength- 152 neverthelessthan indicated stronglyby Stokes, suggest his dataa specimens (sexes combined; Figure 13). shorter life span for this species as compared to both the southern and Stokes (1977) conducted the only summer flounders. The largest female age-growth study of the gulf and male gulf flounders examined by flounder, although Nall's (1979) Stokes were 420 and 290 mm TL, study contained limited data. Both respectively. This is substantially studies were conducted in conjunction smaller than the 710 m TL (5 kg) individual (sex not indicated) reported by Vick (1964) from St. Andrews Bay, Florida. The markedly greater size of Vick's specimen suggests the possibility of species misidentification (most likely with the southern flounder), and thus this record requires confirmation. Nall (1979) presented a graph showing length-weight relationships of gulf flounder, based on 33 specimens Z0 (sexes combined) (Figure 14). IThere is some evidence that areassouthern grow flounderat different from rates, different inde- pendent of differing interpretations of aging techniques (Etzold and Christmas 1979; Nall 1979). This may be due to combinations of differences involving genetic stock, prey availability, temperature and salinity (Deubler 1960; Stickney and White 1973; Peters and Kjelson 1975; , -, Laurence 1977).

STANDARD LENGTH IN MM ECOLOGICAL ROLE Figure 13. Length-weight relationship with fitted curve for southern Food and Feeding flounder. Weight expressed in grams; length in standard length (Nall The three species of Paralichthys 1979). under consideration consume animal l wide variety of animal organisms, with copepod nauplit predominating. Plankton density is an important factor in larval survival, particu- larly since it affects the growth rate of the individual and length of the larval period, which is the time . during which these fish are most vulnerable to predation (Houde and Schekter 1980).

Reid (1954) reported that gulf flounder under 45 mm TL feed primarily on amphipods and other small crustaceans; above this size they begin to feed on fish, which subsequently become the main item in their diet. Stokes (1977) found that, numerically, 95% of the food Items of Juvenile southern flounder (10-150 m TL) from Texas consists of invertebrates. Juvenile southern flounder over 80 mm TL consume "0 u 3 4;0 progressively larger food items as STANDARD LENGTh IN MM the fish increases in size, but there is no indication that large Figure 14. Length-weight relation- adult flounders eat larger prey than ship with fitted curve for gulf subadults (Darnell 1958; Fox and flounder. Weight expressed in White 1969). Powell and Schwartz grams; length in standard length (1979) compared the year-long diets (Nall 1979). of young (100-200 mm TL) summer and southern flounder from Pamlitco Sound, North Carolina (Figure 15). A much higher percentage of empty stomachs matter throughout life. Postlarvae was noted during the winter months. feed on zooplankton and adults feed Powell and Schwartz (1979) found the on benthic and pelagic fishes, as two species to feed on basically the well as crustaceans. same food items. Fish and mysids (malacostracan crustaceans) formed Peters and Angelovlc (1971) reared the bulk of their diet at all postlarval summer flounder on a diet seasons; however, they found the of zooplankton (mostly copepods) and relative percentages of food items Artemia nauplii. Deubler (1958) to be consistently different, with raised postlarvae of summer, the southern flounder feeding more southern, and gulf flounder "to a heavily on fish. They considered definitive size" on brine shrimp that this most likely resulted from (Artemia), white worms (Enchytraeus), differing food availability in the and cut shrimp (Penaeus). Lasswell different habitats occupied by the et al. (1977) found that newly two species (i.e., the summer metamorphosed southern flounder feed flounder prefers higher salinities readily upon rotifers (Branchtonus and a sand bottom, whereas the glicatilis). Houde and Tantguchi southern flounder occurs in lower- (1979) determined that the planktonic salinity water over a mud-silt-clay larvae of many fishes, including bottom); however, they did not dis- species of Paraltchthys, feed on a count the possibility of selective sum ft/wU6M /W~ "Al UM&Darnell 1958; Springer and Woodburn 1960; Fox and White 1969; Topp and -= Hoff 1972; Stokes 1977; Overstreet and Heard 1982). Frequency of _ occurrence of different fish species in the diet appears to depend more on local and/or seasonal prey abundance than on specific prey selection (Darnell 1958; Fox and White 1969). Feeding behavior has only been described for the summer flounder, but presumably is similar for all S Jthree species. The summer flounder is primarily a diurnal feeder that SEASON can capture its prey equally well on the bottom or in the water column Figure 15. Percentage of volume and (Olla et al. 1972; Powell and (in parentheses) percentage of occur- Schwartz 1979). Although it may rence of food items in seasonal diet bury itself in bottom sediments, it of young (100-200 mm TL) summer does not ambush passing prey, but flounder and southern flounder from rather stalks its quarry along the Pamlico Sound, North Carolina. bottom before striking at speeds of Numbers above each bar graph indicate 40 to 50 cm/sec (Olla et al. 1972). number of stomachs with food/total number of stomachs examined (Powell and Schwartz 1979). ENVIRONMENTAL REQUIREMENTS

Substrate feeding, since Williams (1972) has shown that the greatest densities of The three species of Paralichthys mysids in Pamlico Sound are in those under discussion apparently prefer areas where southern flounder predom- specific substrates. Most studies inate, indicate that the summer flounder prefers a hard and/or sandy substrate Larger southern and gulf flounder (Hildebrand and Schroeder 1928; feed proportionally more on fish than Bigelow and Schroeder 1953; Powell on other organisms (Reid 1954; and Schwartz 1979), as does the gulf Springer and Woodburn 1960; Topp and flounder (Ginsburg 1952; Stokes 1977; Hoff 1972; Stokes 1977; Powell and Nall 1979), but the southern flounder Schwartz 1979). Stokes (1977) found is most abundant on soft bottoms that fish comprise more than 70% of comprised of rich organic mud, clay, the food items in individuals over or silt (Ginsburg 1952; Stokes 1977; 150 - TL; penaeid shrimp and blue Nall 1979; Powell and Schwartz 1979). crabs are the most frequently The contrasting relative abundance consumed invertebrates. Genera or of southern and gulf flounder in the species of fishes that have been eastern Gulf of Mexico may reflect found in the diet of both southern these habitat preferences, inasmuch and gulf flounder include mullet as the western gulf (where the (Nui spp.), menhaden (Brevoortia southern flounder predominates) is spp.), Atlantic croaker (Micro- substantially muddier, on the pontas undulatus), and pinfish average, than the eastern gulf (Lagodon rhomboides) (Reid 1954; (Lynch 1954).

16 Tabb and Manning (1961) reported equally distributed over salinities that southern flounder from south- ranging from 0 to slightly over 30 western Florida occur over shell and ppt. Powell (1974), in his analysis firm marl bottoms, but Topp and Hoff of the relative numbers of adult (1972) questioned their species southern and summer flounder in a identifications, since the area where North Carolina estuary, found an these observations were made is inverse relationship between the two outside the known geographic range species with regard to salinity; of this species. Dahlberg and Odum southern flounder predominated at (1970) reported southern flounder in salinities up to 11 ppt (85% of the Georgia from bays with primarily total), but above 11 ppt the summer sand bottoms. Springer and Woodburn flounder predominated (65% of the (1960) collected gulf flounder over a total). Another sharp change in wide variety of habitats in the relative percentages of individuals Tampa Bay area of Florida. Moe and of these two species was noted as Martin (1965) collected a few gulf salinity increased from 17 to 18 flounder near rocky offshore reefs, ppt; at this point the relative and this species occasionally has abundance of summer flounder been found around coral reefs in the increased from 65% to 94%. extreme western Bahamas (Bohlke and Chaplin 1968). Nall (1979), based Juvenile southern flounder appear on observations of 152 specimens, to be more strongly euryhaline than never found southern flounder over an Juveniles of the other two species, exclusively sand bottom, but noted and have been shown to survive abrupt that gulf flounder were somewhat transfer from nearly full-strength less specific with regard to bottom seawater (30 ppt) to freshwater type. Of 33 specimens analyzed, 12 (Deubler 1960). Although Juvenile were collected over a sand bottom, 16 southern flounder have been collected came from a combination sand-mud from North Carolina estuaries at bottom, and 5 were from a strictly salinities ranging from 0.2 to 35.0 mud bottom. ppt (Powell and Schwartz 1977), it appears that a change in salinity tolerance occurs during development Salinity from early postlarval to a more advanced postlarval stage. Early Adult southern flounder, in postlarvae of this species grow most contrast to adult gulf and summer rapidly at higher salinities (ca. 30 flounder, are highly euryhaline, as ppt), but individuals of this size indicated by their frequent occur- (0.1 g) are not very tolerant of rence in rivers (Ross 1980). extremely low salinities; however, Analyses of collections of adult advanced postlarvae do best at southern and gulf flounders from a salinities of 5-15 ppt (Stickney and wide geographic area (Florida to White 1973). Deubler and White Texas) usually indicate a strong (1962) showed that advanced post- preference by the former species for larval summer flounder, by contrast, salinities less than 20 ppt (Gunter exhibit the greatest percentage 1945; Tagatz 1968; Stokes 1977) and weight gain at salinities between 20 by the latter species for salinities and 30 ppt. The differing salinity greater than this (Reid 1954; levels at which optimal development Springer and Woodburn 1960; Stokes of southern and summer flounder 1977). Perret (1971), however, occurs during laboratory experiments reported samples of southern flounder reflect the different natural (totaling about 800 individuals) environmental conditions under which taken from Louisiana estuaries to be these two species are found.

17 Powell and Schwartz (1977) (57.4 0F) in December. Maximum reported collecting juvenile gulf emigration often (though not always) flounder from North Carolina estu- coincided with the passage of cold aries at salinities ranging from 6 to fronts, when sudden drops in tempera- 35 ppt, whereas Williams and Deubler ture (up to 4-50C) occurred. (1968) reported taking them only over a salinity range from 22 to 35 ppt. Williams and Deubler (1968) In both cases, however, it was reported the capture of juvenile indicated that greatest abundance southern and gulf flounders in was found near mouths of estuaries, Atlantic estuaries at water tempera- where salinities were highest. tures as low as 2-40C (35.6-39.20 F), and Gunter (1945) found juvenile Hickman (1968) found that adult southern flounder (17-40 mm) in Texas southern flounder exhibit seasonal estuaries at temperatures from 14.5 changes in osmoregulatory processes to 21.6 0C (58.1-70.90 F). Stokes that correspond to spawning (1977) found that juvenile southern migrations between estuarine and and gulf flounders began to immigrate offshore waters. into Texas estuaries from the Gulf of Mexico at water temperatures as low as 13.8 0C• (56.80 F), but peak Temperature movement occurred between 16.0 and 16.2 0C (60.8-61.20 F). Williams and Adults of the three species of Deubler (1968) reported the capture Paralichthys under discussion have of juvenile summer flounder over a been reported over comparable temperature range of 2-22oC (35.6- temperature ranges. Perret (1971) 71.6 0 F); most individuals were found reported collecting adult southern in the 8-160C (46.4-60.80 F) tempera- flounders from Louisiana estuaries ture range. over a temperature range of 5.0- 34.90C (41.0-94.80 F). These figures Temperature is important in the represent both the minimum and life histories of these species, and maximum temperatures reported for affects such things as time of adults of this species throughout its spawning, movement of adults and range, and exceed the temperature larvae into different habitats, ranges reported by Barrett et al. availability of preferred food (1978) from Louisiana, and by Gunter items, maximal efficiency of food (1945) and Stokes (1977) from Texas. conversion, and rapidity of growth. All temperature data on adult gulf flounders are based on observations from Florida, and range from 8.30C Vegetation (46.90F) (Reid 1954) to 32.5 0C (90.50F) (Springer and Woodburn Aquatic vegetation does not 1960). Powell (1974) reported the appear important to the basic ecology minimum and maximum temperatures at of adult Paralichthys, but is which summer flounders were collected utilized by juveniles. Adams (1976) in Pamlico Sound, North Carolina, to and Orth and Heck (1980) reported range from 70C (44.60F) in February that juvenile summer flounder occur to 290C (84.40F) in July and August. in eelgrass (Zostera marina) beds during daylight hours, ei-ter to take Stokes (1977) found that adults advantage of the cover afforded or to of both the southern and gulf feed on small fish and invertebrates flounders left Aransas Bay, Texas, that congregate there. Stokes during the period when the mean water (1977) found juveniles of both temperature0 dropped from 23.0oC southern and gulf flounders to be (73.4 F) in October to 14.1 0C most abundant in those areas of

18 estuaries where dense patches of The three species are lumped shoal grass (Diplanthera wrightit) together (either as "fluke" or were present and covered 30% to 60% "flounder") in Federal commercial of the total area. Reid (1954) catch statistics (BCF 1939a-1968a; reported juvenile gulf flounder to NMFS 1969a-1977a; BCF 1964b-1968b; be abundant on shallow grass flats NMFS 1969b-1985b). In some cases around Cedar Keys, on the gulf coast they were distinguished from other of northern peninsular Florida. commercially important flatfish species living along the upper Atlantic coast (i.e., north of North Dissolved oxygen Carolina), such as "blackback," or winter flounder (Pseudopleuronectes Deubler and Posner's (1963) americanus) and yellowtail flounder laboratory study of juvenile southern (Limanda ferruginea), whereas in flounder apparently is the only work other cases these species were published on oxygen requirements of combined in catch statistics. any Paralichth.s species. They found Unfortunately, in those cases in that juvenile southern flounder which the above taxa were separated, actively moved into more highly catch statistics were combined for oxygenated water when the dissolved the entire Atlantic coast and Gulf of oxygen concentration fell below 3.7 Mexico (BCF 1964b-1968b; NMFS 1969b- mg/liter. Although they noted 1985b); alternately, when this broad increased general activity with an geographic region was broken down increase in water temperature, there into smaller subregions, these taxa was no increase in sensitivity to were combined (BCF 1939a-1968a; NMFS oxygen depletion at temperature 1969a-1977a). This greatly compli- levels of 6.10, 14.40, and 25.3 0C cates interpretation of catch statis- (43.00, 57.90, and 77.5 °F, respec- tics from the upper Atlantic coast, tively). and allows meaningful comparison M only for the lower Atlantic coast

FISHERY and Gulf of Mexico. For the South Atlantic region, quality and Value of Commercial the total poundage of flounders Fishery remained relatively low until 1945, ranging from 132,000 lb in 1918 to The three species of Paralichthys 1.5 million lb in 1936 (BCF 1939a- under discussion are highly prized 1968a). In 1945, there was an North American food fishes; the increase to about 2.1 million lb, a relative importance of each species circumstance likely related in part is greatest in the area of its to cessation of the war. Catches highest abundance. From late spring dropped during the late 1950's, but into the fall most commercial catches subsequently increased and reached a of these fish are made by shrimp peak of slightly over 5.1 million lb trawlers fishing close inshore or in in 1965, for a total value of just estuaries, and smaller numbers are over 1 million dollars. By 1977 (the caught by individual fishermen last year for which data are "gigging" (i.e., spearing) in the available for this specific area), shallows at night. Lesser numbers of the total catch had risen to 11.4 summer flounder are caught at this million lb, for a total value of 5.1 time in fyke nets, weirs, traps, and million dollars. (Keep in mind that pound nets (Manooch 1984). During dollar values are biased by infla- the winter months, most are caught by tion.) Over 90% of the "flounder" vessels fishing with otter trawls in catch for the South Atlantic area Carolina, and can i deeper waters offshore. comes from North be attributed in large degree to the Comercial catch data for substantially greater abundance of flounder from Florida during the summer flounder in that area, as period 1964-1983 (Fla. Dep. Nat. opposed to farther south. Res., unpub. Florida landings) show results somewhat different from those Total catches of "flounder" from given above. Although total poundage the Gulf of Mexico area are substan- of flounder increased during this tially less, but show a similar period, from a low of 336,600 lb in upward trend. Commercial catches 1967 to a high of 775,400 lb in ranged from a low of 192,000 lb in 1982, the overall importance of 1888 to over 1.1 million lb in 1945, flounder in relation to other edible and had increased slightly to 1.2 commercial marine species in Florida million lb by 1965, for a value of has stayed about the sam. It ranks $231,000. By 1977 the total catch about 15th behind such fishes as amounted to slightly over 1.5 million groupers (several species, the most lb, for a value of $561,000. In important of which is the red contrast to the situation in the grouper); several species of snapper, South Atlantic area, no one State including mangrove, red, and bordering the Gulf of Mexico was yellowtail; spanish mackerel; king dominant in terms of the number of mackerel; striped mullet; sheepshead; pounds harvested. Florida pompano; Jack crevalle; spot; The relative importance of spotted seatrout; king whiting; "flounder"'flunder" innl coercomercial catchestnces hash *anddrums," several such species as Atlantic of "croakers" croaker andor increased substantially in comparison redfish. to most other commercially important marine food species. Prior to 1945, Data from Florida also include a for example, catches of "flounder' breakdown of comercil catches of A along the South Atlantic coast were breakdow ofcor tcag catco f those for flounder according to location (i.e.,- substantially less thenethosethan Atlantic and Gulf of Mexico coasts). croakers or drums (several spe- These show consistently higher cies, but predominantly the Atlantic catches for the gulf coast. In 1969, croaker), bluefish, king mckerel, the catch for the Atlantic coast was spanitsh mckerel, kingftsh or king less than 50% of that for the gulf mullet),whting, seamulet trout, (mostly and spot.striped By forcoast most (120,000 years thevs. relative268,600 percent-lb), but 1965, the total poundage of "floun- ages r s the relative herhent der" exceeded the total for each of ages ranged above 70%, with a high of the above except mullet. By 1977, 88% in 1981 (276,900 vs. 313,200 the total poundage exceeded that for lb). Extremes in yields for the theach toftheof poundaerthe other speciespeced ((most t byoaby • Atlanticlb in 1969 coastto 322,500ranged lbfrom in120,000 1979; substantial amount) except croakers, for the gulf coast these fgures 1 and the total dollar value was f greater than for each of the above ranged from 182,800 lb in 1967 to in both 1965 and 1977 (comparative 404,200 lb in 1979. dollar values are not available prior to 1945). Sport Fishery Recent total poundage and dollar value figures for 'flounder" from Flounder are caught by sport the Gulf of Mexico are well below fishermen using various techniques, those for a number of other commer- such as still fishing, drift fishing, cial fish species, but nevertheless casting from shore, and angling from show an upward trend comparable to piers and banks using live, fresh, that seen for the South Atlantic or frozen baits cast 6 to 18 inches coast. above the bottom (Wisner 1965). 20

LJ Another popular method for catching flounder is one of the most important these fish in some areas is by game fishes, in terms of numbers gigging at night in shallow water, caught, along the mid-Atlantic coast using a long-handled, three-pronged between Cape Hatteras and Cape Cod, spear and a torch or flashlight together with winter flounder, blue- (DeSylva 1965). Sport fishing fish, white perch, spot, scup, and usually begins in the spring (when various searobins. In 1980, it ranked the fish return from deeper waters second only to bluefish, but in 1979 offshore, where they have spent the it ranked about fifth in number. winter), and continues into the fall. Based on average size of individuals caught, it would rank well ahead of Sport catch statistics for the all of the above except winter Atlantic and gulf coasts (NMFS 1969b- flounder and bluefish. Along the 1985b) are more informative than co- south Atlantic and gulf coasts, mercial catch statistics because however, the numbers of flounder individual species are identified. caught are well below those for many These data indicate that the summer other sport species.

-~I.

%A LITERATURE CITED

Adams, S. M. 1976. The ecology of Bureau of Commercial Fisheries (BCF). eelgrass, Zostera mrina (L.), fish 1939a-1968a. Fishery Statistics communities. I. Structural of the United States 1/62. U. S. analysis. J. Exp. Mar. Biol. Ecol. Dep. of the Interior. 22:269-291. Bureau of Commercial Fisheries (BCF). Arhold, C. R., V. H. Bailey, T. D. 1964b-1968b. Fisheries of the Williams, A. Johnson, and J. L. United States. Curr. Fish. Stat. Lasswell. 1977. Laboratory spawn- 4100/5000. U.S. Dep. Interior. tIg and larval rearing of red drum and southern flounder. Proc. Dahlberg, M. D., and E. P. Odum. Southeast. Assoc. Fish Wildl. 1970. Annual cycles of species Agencies 31:437-440. occurrence, abundance, and diver- sity in Georgia estuarine fish Balon, E. K. 1975. Terminology of populations. Am. Midl. Nat. 83: intervals in fish development. J. 382-392. Fish. Res. Board Can. 32:1663-1670. Daiber, F. C., and R. W. Smith. Barrett, B. B., J. L. Merrell, T. P. 1969. An analysis of the summer Morrison, N. C. Gillespie, E. J. flounder population in the Ralph, and J. F. Burdon. 1978. A Delaware Bay area. Annu. Dingell- study of Louisiana's major Johnson Rep. (1968-1969), Proj. estuaries and adjacent offshore F-13-R-11. Delaware Board Game waters. La. Dep. Wildl. Fish. Fish. Com. 26 pp. Tech. Bull. 27. 197 pp. Darnell, R. N. 1958. Food'habits of Benson, N. G., ed. 1982. Life fishes and larger invertebrates of history requirements of selected Lake Pontchartrain, Louisiana, an finfish and shellfish in Missis- estuarine community. Publ. Inst. sippi Sound and adjacent areas. Mar. Sci. Univ. Texas 5:353-416. U.S. Fish Wildl. Serv. FWS/OBS-81/ 51. 97 Pp. DeSylva, 0. P. 1965. Southern flounder, Paralichthys lethostima. Bigelow, H. B., and V. C. Schroeder. Page 910 in A. J. McClaneas new 1953. Fishes of the Gulf of Maine. standard -fishing encyclopedia. U.S. Fish Wildl. Serv. Fish. Bull. Holt, Rinehart and Winston, New 53:1-577. York. Bohlke, J. E., and C. C. G. Chaplin. Deubler, E. E., Jr. 1958. A com- 1968. Fishes of the Bahamas and parative study of the postlarvae of adjacent tropical waters. Living- of three flounders (Paralichthrys) ston Publishing Co., Wynnewood, in North Carolina. Copeia 1958(2): Pa. 771 pp. 112-116. 23 Deubler, E. E., Jr. 1960. Salinity Hickman, C. P., Jr. 1968. Glomeru- as a factor in the control of lar filtration and urine flow in growth and survival of postlarvae the euryhaline southern flounder, of the southern flounder, Para- Paralichthys lethostigma, in 11chthys lethosttama. Bull. -at. seawater. Can. J. Zool. 46: &- -GtuTf ibb.10:3 39-345. 427-437. Deubler, E. E., Jr., and G. S. Hildebrand, S. F., and L. E. Cable. Posner. 1963. Response of post- 1930. Development and life larval flounders, Paralichthys history of fourteen teleostean lethostigma, to water of low fishes at Beaufort, N. C. Bull. oxygen 1963(2):312-317.concentrations. Copeia U. S. Bur. Fish. 46:383-488. Hildebrand, S. F., and W. C. Deubler, E. E., Jr., and J. C. White, Schroeder. 1928. Fishes of Chesa- Jr. 1962. Influence of salinity peake Bay. Bull. U. S. Bur. Fish. on growth of postlarvae of the 43:1-366. summer flounder, Paralichthys dentatus. Copeia 1962(2):468-469. Hoese, H. D., and R. H. Moore. 1977. Fishes of the Gulf of Mexico: Eldridge, P. J. 1962. Observations Texas, Louisiana, and adjacent on the winter trawl fishery for waters. Texas A & M Press, summer flounder, Paralichthys College Station. 327 pp. dentatus. M. S. Thesis, College oft111am and Mary, Williamsburg, Houde, E. D., and R. C. Schekter. Va. 58 pp. 1980. Feeding by marine fish larvae: development and functional Etzold, D. J., and J. Y. Christmas, responses. Environ. Biol. Fishes eds. 1979. A Mississippi marine 5:315-334. finfish management plan. Miss.- Ala. Sea Grant Consortium Houde, E. D., and A. K. Taniguchi. MAGSP-78-046. 36 pp. 1979. Laboratory culture of marine fish larvae and their role in marine Fox, L. S., and C. J. White. 1969. environmental research. Pages 176- Feeding habits of the southern 205 in F.S. Jacoff, ed. Advances in floudeednflounder habinin BaratariaBartaa s Bay,n Proc.mariiii Sym.,environmental Environ. Res.research. Lab.,I Louisiana. Proc. La. Acad. Sc. 32:31-38. U.S. Environ. Protect. Agency, Narragansett, R.I. Rep. EPA-600/ Ginsburg, I. 1952. Flounders of 9-79-035. the genus Paralichthys and related Johns, D. M., and W. H. Howell. 'I genera in Amrcan waters. Fish. 1980. Yolk utilization in sumer Bull. U.S. Fish Wildl. Serv. flounder (Paralichthys dentatus) 52:267-351. embryos and larvae reared at two temperatures. Mar. Ecol. Prog. Gunter, G. 1945. Studies on marine Ser. 2:1-8. fishes of Texas. Publ. Inst. Mar. Sci. Univ. Texas 1(1):1-190. Johns, D. M., W. H. Howell, and G. Klein-MacPhee. 1981. Yolk Gutherz, E. J. 1967. Field guide to utilization and growth to yolk-sac the flatfishes of the family absorption in summer flounder Bothidae in the western North (Paralichthys dentatus) larvae at Atlantic. U.S. Fish Wildl. Serv. constant and cycl1tctemperatures. Circ. 263. 47 pp. Mar. Biol. (Berl.) 63:301-308. 24 Lasswell, J. L., G. Ganza, and W. H. Morse, W. W. 1981. Reproduction of I Bailey. 1977. Status of marine the summer flounder, Paralichthys fish introduction into the dentatus (L.). J. Fish Biol. 19: freshwaters of Texas. Proc. 18-0. Southeast. Assoc. Fish Wildl. Agencies 31:399-403. Murawski, V. S. 1970. Results of Laurence, G. C. 1977. A btoener- flounder,tagging experimentsParalichths of dentatus,summer getic model for the analysis of conducted tn New Jersey waters feeding and survival potential of from 1960 to 1967. N. J. Dep. winter flounder, Pseudopleuronectes Environ. Protect. Bur. Fish. Misc. americanus, larvae during the Rep. 5M. 52 pp. period from hatching to metamorphosis. U.S. Natl. Mar. Fish. Serv. Nall, L. E. 1979. Age and growth of Fish. Bull. 75(3):529-546. the southern flounder (Paral- ichthys lethostiga) in the northern Lem, A. H., and W. B. Scott. 1966. GiuT--ofNTexlco with notes on Fishes of the Atlantic coast of Paralichths albigutta. M.S. Canada. Bull. Fish. Res. Board hesis, lorida 3tateUniversity, Can. 155:1-485. Tallahassee. 58 pp. Lux, F. E., and F. E. Nichy. 1981. National Marine Fisheries Service Movements of tagged summer (NMFS). 1969a-1977a. Fishery flounder, Paralichthys dentatus, Statistics of the United States off southern New England. U. S. 63-71. U. S. Dep. of Commerce. Natl. Mar. Fish. Serv. Spec. Sct. Rep. Fish. 752:1-16. National Marine Fisheries Service (NMFS). 1969b-1985b. U. S. Natl. Lynch, S. A. 1954. Geology of the Mar. Fish. Serv. Curr. Fish. Stat. Gulf of Mexico. Pages 67-86 in 5600/8360. U. S. Dep. of Commerce. Gulf of Mexico: its origin, waters, and marine life. Fish. Bull. U.S. Olla, B. L., C. E. Samut, and A. L. Fish Wildl. Serv. 55:1-604. Studhome. 1972. Activity and feeding behavior of the summer Manooch, C. S., III. 1984. Fisher- flounder (Paralchthys dentatus) man's guide: fishes of the south- under controlled laboratory eastern United States. N.C. State conditions. U.S. Natl. Mar. Fish. Mus. Nat. Hist., Raleigh. 362 pp. Serv. Fish. Bull. 70(4):1127-1136. Orth, R. J., and K. L. Heck, Jr. Martin, F. D., and G. E. Drewry. 1980. Structure components of 1978. Development of fishes of eelgrass (Zostera marina) meadows the mid-Atlantic Bight. Vol. VI. in the lower Chesapeake Bay - Stromateidae through Ogcocephal- fishes. Estuaries 3:278-288. idae. U.S. Fish Wildl. Serv. Biol. Serv. Program FWS/OBS-78/12. 416 Overstreet, R. M., and R. W. Heard. PP. 1982. Food contents of six commercial fishes from Mississippi Moe, M. A., Jr., and G. T. Martin. Sound. Gulf Res. Rep. 7:137-149. 1965. Fishes taken on monthly trawl samples offshore of Pinellas Perret, W. S. 1971. Cooperative County, Florida, with new Gulf of Mexico estuarine inventory additions to the fish fauna of the and study, Louisiana. Phase IV, Tampa Bay area. Tulane Stud. Biology. La. Wildl. Fish. Comm. Zool. 12:129-151. 175 pp. 25

''IeP' r" w ' A-', __ .1

Peters, D. S., and J. V. Angelovic. Powell, A. B., and F. J. Schwartz. 1971. Effect of temperature, 1979. Food of Paralichthys salinity, and food availability on dentatus and P. !ehostign tb and energy utilization of (Pisces: Bothidae) in North venile sier flounder, pata- Carolina estuaries. Estuaries dentatus. Pages 54FW5 2:276-279. T eison, ed. Radionuclides I% ecosystem. National Symposium Reid, G.K., Jr. 1954. An ecological on Radloecology, Oak Ridge, Tenn. study of the Gulf of Mexico fishes in the vicinity of Cedar Key, Peters, D. S., and N. A. KIelson. Florida. Bull. Mar. Sci. Gulf 1975. Consumption and utilization Caribb. 4:1-94. of food by various postlarval and juvenile fishes of North Carolina Rogers, S. G., and M. J. Van Den estuaries. Pages 448-472 in L. E. Avyle. 1983. Species profiles: Cronin, ed. Estuarine research. life histories and environmental Vol. 1. Chemistry, biology, and requirements of coastal fishes and the estuarine system. Academic invertebrates (south Atlantic). Press, Now York. Simmer flounder. U.S. Fish Wild]. Serv. FWS/OBS-82/11.15. 14 pp. Policansky, D. 1982. Influence of age, size, and temperature on meta- Ross, S. V. 1980. araichtys morphosis in the starry flounder, lthsttgp Jordan Platichthvs stellatus. Can. ,. souithernFflounder. Pageand 829G29birt, in D. Flis At. Scl. 39:514-517. S. Lee et al. American Atlas of North freshwater fishes. N. C. Poole, J. C. 1961. Age and growth State Mus. Nat. Hist., Raleigh. of the fluke in Great South Bay and 854 pp. their significance to the sport Simmons, E. G., and H. D. Hoese. fishery. N. Y. Fish Gam 3. 8: 1959. Studies on the hydrography 1-18. and fish migrations of Cedar Bayou, Poole, J. C. 1962. The fluke popu- centrala natural Texas tidal coast. inlet Pub1.on Inst.the lation of Great South Bay in rela- Mar. Sl Univ Texas 6:56-80. tion to the sport fishery. N.Y. " " T " Fish Game J. 9:93-117. Smith, R. W. 1969. An analysis of Poole, J. Pool,C. 1966.J966 A rviereview of dentatus,the summer populationflounder, inParalichthys the Dla- research concerning summer flounder arueBa. M.S. Thesis, University and needs for further study. N. Y. of Delaware, Newark. 72 pp. Fish Gam J. 13:226-231. Smith, R. W., and F. C. Daiber. Powell, A. B. 1974. Biology of the 1977. Biology of the summer summer flounder, Paralichthys flounder, Paralichthys dentatus, dentatus, in Pamlico nd and in Delaware Bay. U.S. Natl. Mar. adjacent waters, with comments on Fish. Serv. Fish. Bull. 75(4):823- P. lethostigma and P. albigutta. 830. A. S Thesis, University of North Carolina, Chapel Hill. 145 pp. Smith, R. W., L. M. Dery, P. G. Scar- lett, and A. Jearld, Jr. 1981. Powell, A. B., and F. J. Schwartz. Proceedings of the summer flounder 1977. Distribution of paralichthid (Paralichthys dentatus) age and flounders (Bothidae: Paralichthys) growth workshop. V. S. Dep. in North Carolina estuaries. Commer., NOAA Tech. Memo, Chesapeake Sci. 18:334-339. NMFS-F/NEC-11. 30 pp. 26 Smith, W. G. 1973. of sumer flounder,The distributionParalchthslatfishes To% R.W., and F.H.(Pleuronectiformes). Hoff, Jr. 1972. dentatus, eggs and larvae on the Hem. Hourglass Cruises 4(2):1-135. Continental Shelf between Cape Cod and Cape Lookout, 1965-1966. Vick, N. G. 1964. The marine ich- U.S. Natl. Mar. Fish. Serv. Fish. thyofauna of St. Andrew Bay, Bull. 71:527-548. Florida, and nearshore habitats of the Gulf of Mexico. Texas A & M Springer, V. G., and K. D. Woodburn. Univ. Res. Found. Proj. 286-D. 77 pp. 1960. An ecological study of the fishes of the Tampa Bay area. Fla. Weinstein, M. P., S. L. Weiss, R. G. State Board Conserv. Mar. Lab. Hodson, and L. R. Gerry. 1980. Prof. Pap. Ser. 1:1-104. Retention of three taxa of postlarval fishes in an intensively Stickney, R. R., and D. B. White. flushed tidal estuary, Cape Fear 1973. Effects of salinity on the River, North Carolina. U.S. Natl. growth of Paralichthys lethostga Mar. Fish. Serv. Fish. Bull. 78(2): postlarvae reared under aquaculture 419-436. conditions. Proc. Southeast. Assoc. Fish Wildl. Agencies 27: Wilk, S. W., W. G. Smith, D. E. 532-540. Ralph, and J. Sibunka. 1980. Population structure of summer Stokes, G. N. 1977. Life history flounder between New York and studies of southern flounder Florida based on linear discrimi- (Paralichthls lethosttgm) and gulf nant analysis. Trans. Am. Fish. flounder (P. ab igjta) in the Soc. 109:265-271. Aransas Bay area Of Texas. Tex. Parks Wildl. Dep. Tech. Ser. 25:1- Williams, A. B. 1972. A ten-year 37. study of meroplankton in North Carolina estuaries: mysid shrimps. Tabb, D. C., and R. B. Manning. Chesapeake Sc. 13(4):254-262. 1961. The biota of Florida Bay. Bull. Mar. Sc. Gulf Caribb. 11: Williams, A. B., and E. E. Deubler. 552-649. 1968. A ten-year study of meroplankton in North Carolina estuar- Tagatz, M. E. 1968. Fishes of the ies: assessment of environmental St. Johns River, Florida. Q. J. factors and sampling success among Fla. Acad. Sci. (1967) 30:25-50. bothid flounders and penaeid shrimps. Chesapeake Sci. 9:27-41. Tagatz, N. E., and G. L. Dudley. 1961. Seasonal occurrence of Wisner, W. 1965. Summer flounder, marine fishes in four shore Parelichthys dentatus. Pages 987- habitats near Beaufort, North 991 in A.J. NcClane's new Carolina, 1957-1960. U. S. Fish standar fishing encyclopedia. Wildl. Serv. Spec. Sc. Rep. Fish. Holt, Rinehart and Winston, New 390. 19 pp. York.

27 -j REM1 SOCVMENTATION I- SEPOOT NO,.- -- 121LXtpW cesele PAG O Biological Report 82(11.54)*T _ _ 4. Two aod sIum L Oatft Species Profiles: Life Histories and Environmental Requirements July 1986 of Coastal Fishes and Invertebrates (South Florida)--Southern, Gulf, and Sumer Flounders 7. &imae(a Carter R. Gilbert 8. Psfmdnu Orundata Saei.us I k. P tInin Oqanzase "Wainsd Addiaga 10. P oJect/Taa&/WaerU.N Na, Florida State Museum University of Florida i,.Ce"raetr oraraftm .. Gainesville, FL 32611 CU

12. 'eneaserf Ovnm~ Name aed Ad*saa _ _ _ National Wetlands Research Center U.S. Amy Corps of Engineers IL TyVpeenAPeiod Covered Fish and Wildlife Service Waterways Experiment Station

U.S. Department of the Interior P.O. Box 631 _ Washington, DC 20240 Vicksburg, MS 39180

IL. Susgiamu~taq MOMe *U.S. Army Corps of Engineers Report No. TR EL-82-4 .& A'A (Lt NO w ) Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal species. The southern, gulf, and summer flounder live most of their lives in or near estuaries. Adults migrate into offshore waters during fall and winter, where spawning occurs from September to April. Eggs and newly-hatched larvae are carried inshore into estuaries, where further growth takes place. Age at sexual maturity for the three species has been estimated from 2 to 4 years, and maximum longevity from 3 to 10 years. Females apparently live slightly longer than males. Southern and summer flounders are estimated to live slightly longer than the smaller gulf flounder. Postlarvae eat mostly zooplankton, and larger individuals feed on fish and crustaceans. The summer and gulf flounders prefer a hard and/or sandy substrate, whereas the southern flounder is more common in a soft bottom of rich organic mud, clay, or silt. The southern flounder, unlike the other two species, is highly euryhaline, and frequently occurs in fresh water. Commercial catch statistics lump the three species together under the name "flounder." Peak commercial catch in the Gulf of Mexico (in 1977) was 1.5 million lb, for a value of $561,000; peak catch in the south Atlantic region (also in 1977) was 11.4 million lb, for a value of $5,100,000.

17. Suamme g a. Ms e Estuaries ses Fisheries Flatfishes Salinity Temperature Feeding Habits Life Cycles Growth Southern flounder Gulf flounder Summer flounder Paralichthys lethostgma Paralichthys albigutta Paralichthys dentatus Temperature requirements Spawning Commercial importance Life history Habitat requirements a.(:OSA rlsi~d/Gs iU Avausoy staiONs 19. Scurity CloSs(This Rpet) 21. Ne. of Pages O2L Pta 27 UnlWANSI-ZIS.fjI mi ted Is,,age)

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