Reproduction and Growth of Black Drum, Pogonias cromis, in Northeast Florida

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1 Gulf of Mexio Siene Volume 10 Number 2 Number 2 Artile Reprodution and Growth of Blak Drum, Pogonias romis, in Northeast Florida Mihael D. Murphy Florida Marine Researh Institute Ronald G. Taylor Florida Marine Researh Institute DOI: /negs Follow this and additional works at: Reommended Citation Murphy, M. D. and R. G. Taylor Reprodution and Growth of Blak Drum, Pogonias romis, in Northeast Florida. Gulf of Mexio Siene 10 (2). Retrieved from This Artile is brought to you for free and open aess by The Aquila Digital Community. It has been aepted for inlusion in Gulf of Mexio Siene by an authorized editor of The Aquila Digital Community. For more information, please ontat Joshua.Cromwell@usm.edu.

2 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Northeast Gulf Siene Vol. 10, No. 2 August REPRODUCTION AND GROWTH OF BLACK DRUM, Pogonias romis, IN NORTHEAST FLORIDA Mihael D. Murphy and Ronald G. Taylor Florida Marine Researh Institute Department of Natural Resoures 100 Eighth Ave. S.E. St. Petersburg, FL ABSTRACT: Age, growth, and reprodution of blak drum, Pogonias romis, in northeast Florida were investigated between Deember 1983 and April1985. Male blak drum began maturing at mm total length (TL), with 50% of them reahing maturity at about 590 mm (age 4 or 5). Vitellogenesis began at mm TL, with 50% of the females reahing maturity at mm (age 5 or 6). Spawning ourred during January April. Thin setions of otoliths displayed distint opaque bands; the first three or four of these bands were verified by marginal inrement analysis as being annuli deposited during Marh May. The growth rate was about 100 mm yr- for ages 1 3 and gradually slowed to mm yr-' for ages Male and female growth rates did not differ signifiantly, at least through age 4. Length at age was predited well by the equation mm TL = 1172 mm (1 - exp ( (AGE+ 1.3)) ). The apparent maximum age of blak drum is about years. Blak drum, Pogonias romis, sup port moderate ommerial and rerea tiona! fisheries in Florida. Rereational athes of blak drum along the Florida Atlanti oast inreased from 122,000 lbs in 1981 to 628,000 lbs in In north east Florida, a rereational fishery for large blak drum develops during the spring as adults ongregate in sounds and passes. Smaller "puppy" drum are aught by rereational fishermen, and inidentally in ommerial athes, throughout the year. Annual ommerial landings of blak drum ranged from between 35,000 to 150,000 lbs on the Florida Atlanti oast between 1950 and 1985 and have averaged about 60,000 lbs sine Reent development of a purse seine fishery for large blak drum and red drum (Siaenops oellatus) in the northern Gulf of Mexio, however, suggests that the potential exists for exploitation of the large, offshore stoks of adults 2 Knowledge of the biology of Florida blak drum has primarily been obtained from anillary information inluded in faunal studies. The spawning season, as determined by studying larval and juve nile olletions, ours during late fall and winter in south Florida (Jannke, 1971) and during winter and early spring in northern and entral Florida (Reid, 1954; Kilby, 1955; Joseph and Yerger, 1956; Springer and Woodburn, 1960). Sales and/or otoliths have been used to determine the ages and to desribe the growth of adult drum in Georgia (Musi and Pafford, 1984), Virginia (Rihards, 1973), and Texas (Pearson, 1929; Sim mons and Breuer, 1962; Cornelius, 1984). The growth rates of juvenile blak drum in Texas have been determined by ana lyzing length-frequeny modes (Pearson, 1929; Simmons and Breuer, 1962). Tagging programs have also provided information 'Robert Muller, Florida Marine Researh Institute, Department of Natural Resoures, 100 Eighth Ave. S.E., St. Petersburg, FL 33701, personal omm., Marine Rereational Fisheries Statistis Survey data. 2 NOAA, National Marine Fisheries Servie. Proposed seretarial fishery management plan, regulatory impat review, initial regulatory flexibility analysis, and draft environmental impat statement for the red drum fishery of the Gulf of Mexio. August Published by The Aquila Digital Community,

3 128 Murphy, M. D., and R. G. Taylor Gulf of Mexio Siene, Vol. 10 [1988], No. 2, Art. 6 on drum growth in Texas bays (Doerzbaher, 1988). This study desribes the maturation, spawning, age determination, rates of growth, and the weight-length and length-length relations of blak drum sampled from the inshore Atlanti waters of northeast Florida. The fishery impliations of these results are briefly disussed. METHODS AND MATERIALS Blak drum were olleted monthly from the ommerial and rereational athes made at Amelia Island (30 35'N, 81 30'W), in northeast Florida, south to St. Augustine (29 55'N, 81 15'W) from Deember 1983 through April No samples were obtained in September and November 1984 and February All fish were measured for total (TL), fork (FL), and standard lengths (SL); sexed; and weighed for whole weight (W) to the nearest oune. Eah month, up to 40 of these fish were also sampled for gonads and otoliths (sagittae). Gonads were preserved in Davidson's fixative (Humason, 1972). Otoliths were washed in water and then stored dry in vials stoppered with otton. Unless otherwise noted, all lengths presented are total length (TL). Preserved gonads were soaked in water for 24 h in the laboratory, blotted dry, and weighed to the nearest 0.1 g. After drying, a sample of eah gonad was stored in 70% ethanol. This sample was later embedded in paraffin, setioned to 6 um thikness, stained with Mayer's haematoxylin and eosin Y, and mounted for mirosopi examination. The seasonal yle of male and female gonadal development was divided, based on the histologial riteria of Wallae and Selman (1981) for oogenesis and Grier (1981) for spermatogenesis, into eight DOI: /negs lasses (Table 1). Individuals of eah sex were onsidered funtionally mature at Class 4 or greater. Size at maturity was determined by grouping fish by sex into 50 mm size lasses and alulating the perentage of mature fish in eah size lass. Spawning season was determined by noting hanges in mean ooyte diameters throughout the study period. Ooyte diameters were measured with an oular mirometer, and only ooytes whose nulei were inluded in the ross setion were measured (Fouher and Beamish, 1980). One hundred ooytes in a ommon, randomly seleted lamella were measured in eah ovary to alulate mean ooyte diameters within samples. Ten of the largest ooytes from eah gonad setion were also measured to alulate the mean-maximum ooyte diameter. Sagittae were setioned for age determination using a Beuhler lsomet Low-Speed Saw with a diamond blade. Two 0.5-mm-thin transverse setions were ut from eah sagitta and mounted on mirosope slides with Coverbond Mounting Media. The setion that interseted the ore of the otolith was examined for age marks under a disseting mirosope using refleted light. The medial transverse distanes from the ore to the proximal edge of eah opaque band and to the edge of eah setion (otolith radius, OR) were measured with an oular mirometer. Ages were determined for all fish, inluding those age 0 +,by assuming a biologially realisti hathing date of 1 April and inrementing ages from this date. The suitability of using otolith setions to bak-alulate fish lengths in order to study individual fish growth was tested by least squares regression of fish length on otolith setion radius. The modified diret proportionality formula was used to bak-alulate 2

4 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Reprodution and growth of blak drum 129 Table 1. Reprodutive lasses of blak drum gonads by sex. CLASS FEMALE 1. Immature Few folds of ovigerous lamellae; few or no primary ooytes; oogonia predominate; diameter of ovary <3.0 mm. 2. Developing I Resting Virgin Ovigerous lamellae fill lumen of entire gonad; abundant primary ooytes; oogonia present at periphery of lamellae. Absene of atreti bodies; tunia thikened. 3. Maturing Early vitellogenesis; oogonia, primary ooytes and ooytes with yolk vesiles present; ommenes in late Otober-November. 4. Mature Late vitellogenesis; oogonia, primary oytes, ooytes with yolk vesiles and globules present. 5. Gravid Maturation, oogonia, primary ooytes, ooytes with yolk vesiles and yolk globules present; nulei of most advaned ooytes have migrated in preparation for ovulation. 6. Spawning Amorphorus, hydrated ooytes present; ooytes in all stages of development; fragments of ruptured ooytes sattered throughout; ollapsed empty folliles present; yolk remnants usually present in onnetive tissue and lamellae; tunia greatly thikened. 7. Spent Oogonia and primary ooytes present in budding ovigerous lamellae; ovary with "empty" areas; "plugs" of unshed ooytes present, atreti bodies sattered throughout, usually in assoiation with blood vessels. 8. Reovering Prolifi rerudesene of ovigerous lamellae with myriad oogonia and stage II ooytes; atreti bodies present; the tunia with many onvolutions. MALE Non-reprodutive; only spermatogonia present; no evidene of tubule development. Early spermatogenesis; few sattered ysts of primary spermatoytes; peripheral tubules differentiating; lumen not developed. Mid spermatogenesis or ripening; spermatogonia and ysts of spermatoytes present along tubules, limited prodution of spermatids. Late spermatogenesis; ripe; few spermatogonia along tubule; spermatozoa olleting in tubules and entral lumen. Delining number of spermatogeni ysts; efferent duts filled with spermatozoa; lumen of entral dut partially filled with spermatozoa. Efferent duts filled with spermatozoa; spermatozoa streaming into main olleting dut; distal portions of a few efferent tubules empty and somewhat thikened; spermatogonia absent. No spermatogonia or spermatoytes present; efferent tubules empty; lumen of entral olleting dut with small amount of residual sperm; testis greatly redued in size; tuni of previous spawners thikened and onvoluted. Network of efferent tubules lined with spermatogonia; numerous PAS leukoytes "leaning up" the entral sinus; some ysts of spermatoytes re-appear in mid May-June. lengths (Bagenal and Tesh, 1978) only for blak drum ages 1-4 beause few older fish were sampled. The Statistial Analysis System (SAS Institute, In. 1982) was used to alulate all regressions; PROBIT analysis of size-lass midpoints was used to alulate the lengths at 50% maturity. The NUN proedure (Marquardt option) of SAS was used to fit age-length data to the von Bertalanffy growth model (Vaughan and Kaniruk, 1982) and weight- length data to the allometri growth model, W =a TLb. Estimates of "a" and "b" of the allometri growth model were tested for differenes using the Student's t - test (O< = 0.05). Published by The Aquila Digital Community,

5 Gulf of Mexio Siene, Vol. 10 [1988], No. 2, Art Murphy, M.D., and R. G. Taylor RESULTS AND DISCUSSION Size and Age at Maturity In northeast Florida, male blak drum (n = 181) matured at slightly smaller sizes and younger ages than did females (n = 158). Male sexual maturation began when lengths of mm were reahed at age 2 (Table 2). PROBIT analysis indiated that 50% of all males reahed maturity at lengths of about 590 mm at ages 4 or 5. Total maturity was attained at approximately 675 mm and probably age 6. Early vitellogenisis was evident for immature females at lengths of mm. All females less than 650 mm were immature and all greater than 650 mm were mature; onsequently, 50% and total maturity were attained when lengths of between 650 mm and 699 mm were reahed at age 5 or 6 (Table 2). Maturation of male blak drum had not been desribed prior to this study. The size and age at whih female blak drum from northeast Florida mature were similar to those figures reported for female blak drum in Georgia waters; female blak drum in the western Gulf of Mexio, however, were smaller and younger at maturity than were those from northeast Florida. In Georgia, Musi and Pafford (1984) found that the smallest female exhibiting developing ovaries was 582 mm and age 4. Marosopi examination of females in Texas with "granular gonads" suggested maturity was reahed at mm, at the end of their seond year (Pearson, 1929; Simmons and Breuer, 1962). Spawning Season Mean and mean-maximum ooyte diameters of blak drum peaked in April 1984 and Marh 1985 (Fig. 1). Some spawning ativity during January- Marh 1984 was evidened by elevated mean 500 e 4oo :::. ffi tii 300 ~ ;:::; w 200 t t.'ean MAX MUM I MEMl /;' t:,, IJ //,, ' " ;/ ::::--~.::.:::1" D J F M A M J J A 5 0 N D! J ~ 98 ~ A COLLECTION MONTH Figure 1. Mean and mean-maximum oo.yte diameters for P. romis for eah monthly olletion. and mean-maximum ooyte diameters. Adult blak drum of both sexes sampled from Tampa Bay, whih is loated along the Florida Gulf oast, were also in spawning ondition during February and Marh The overall observed sex ratio (202M:169F) for blak drum mm long was not signifiantly different (x 2 test, p>0.05) from the expeted 1 M:1 F sex ratio. Data gathered from adult, juvenile, and larval olletions made in other areas generally agree on blak?rum spawning seasonality. Adults were In advaned stages of maturity during Marh and April off Georgia (Musi and Pafford, 1984). In the Biloxi marsh omplex of southeast Louisiana, blak drum had ripe gonads during Marh- May (Fontenot and Rogillo, 1970). Examination of larval and juvenile olletions provided evidene that suggested a late fall and winter spawn in south Florida (J annke, 197.1) and a winter- early spring spawn 1n entral and northern Florida (Reid, 1954; Kilby, 1955; Joseph and Yerger, 1956; Springer and Woodburn, 1960). Two spawning peaks per year have be~n noted for blak drum in Texas: a ma1n peak in late winter- early spring and a lesser peak in early fall (Pearson, 1929; Simmons and Breuer, 1962)- Most adults with advaned gonadal development have been olleted during February May; however, a few near I y ripe blak DOI: /negs

6 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Reprodution and growth of blak drum 131 Table 2. Fration of blak drum mature (sample size in parentheses) in 50 mm size lasses and for age groups 1. 14, :;,: LENGTH TL(mm) Male Female (16) 0 (17) (25) 0 (19) ( 7) 0 (13) (30) 0 (18) (21) 0 (25) (20) 0 (15) (14) 0 ( 9) (24) 0 (13) ( 6) 0 ( 7) ( 3) 1.0 ( 2) ( 2) -( 0) ( 0) -( O) ( 2) 1.0 ( 1) ( 4) 1.0 ( 2) ( 1) 1.0 ( 4) ;;, (13) 1.0 (13) AGE Age (yrs) Male Female 0 0 (24) 0 (27) 1 0 (48) 0 (47) (49) 0 (33) (30) 0 (18) (12) 0 ( 9) ( 4) 0.50 ( 2) 6 ( 0) 1.0 ( 2) 7 ( 0) ( 0) ( 3) 1.0 ( 1) ( 1) 1.0 ( 3) ( 1) 1.0 ( 1) ( 1) ( 0) ( 1) ( 0) ( 1) 1.0 ( 2) 14 ( 0) 1.0 ( 1) ;;, (13) 1.0 (12) drum have been olleted in July and August (Pearson, 1929). Examination of juvenile length frequenies reveals evidene that supports the possibility of a seondary spawning season in June or July (Simmons and Breuer, 1962). More reently, analysis of gonosomati indies (GSI) of south Texas blak drum showed a primary spawning peak in Marh, with a seondary peak in August for males, and a primary peak in February, with a seondary peak in Otober for females (Cornelius, 1984). However, mean ooyte diameters were largest during February April 1978 and January- May 1979 and smallest during August 1978 and July 1979 (Cornelius, 1984). Spawning adults have been olleted in 5-37 m water off Texas during November- April; peak spawning ativity ourred during January- April (Ross et at., 1983; Cody et at., 1985). Spawning apparently ours slightly later in more northern latitudes along the Atlanti oast, e.g., from Marh- May in Chesapeake Bay and Delaware Bay (Frisbie, 1961). Age Determination and Growth Thin opaque and wide transluent bands were learly disernable on blak drum otolith setions. Two independent readers agreed on 82% (326 of 399) of the total opaque band ount after their first reading. After a seond, joint reading, all but two band ounts were agreed upon, providing 397 fish for age and growth analysis. Most initial disagreements onerning band ounts (75%) involved fish olleted during the period of January Marh, when newly formed age marks were diffiult to disern. Fish having 0-58 opaque bands were analyzed; about 80% had 0-4 bands. Males with up to 48 bands were sampled; 4.6% (9 of 198; all greater than 1150 mm) had more than 30 bands. Females with up to 58 bands were sampled; 6.7% (11 of 164; all greater than 1115 mm) had more than 30 bands. The trends in the monthly mean marginal inrement give evidene that supports the designation of opaque bands as annuli for ages 1-3 and probably age 4. For ages 1-3, mean marginal inrements were greatest during Deember 1983 through Marh 1984 and then delined in April and May (Fig. 2). The mean marginal inrement for the few age 4 fish sampled delined from Deember Published by The Aquila Digital Community,

7 Gulf of Mexio Siene, Vol. 10 [1988], No. 2, Art Murphy, M.D., and R. G. Taylor 1983 through Marh The mean marginal inrement was smallest in the spring; it then inreased and remained large for ages 1-4 through the end of After January 1985, the mean marginal inrement generally delined, although few fish ages 2-4 were sampled. Although validation is still needed to define opaque bands that are distal to the third or fourth band as annuli, we assume in this report that all opaque bands are annuli. Reent findings for a losely related speies, red drum (Siaenops oellatus), onfirmed that opaque bands were annuli through at least age 18 (Murphy and Taylor 3 ). Prior to this study, indiret verifiation of the effiay of using thinsetioned otoliths to determine blak drum ages had not been demonstrated. The lengths of one- to two-year-old fish whose ages were determined by sale examination have been shown to be onsistent with the lengths of fish these ages that were estimated by using length frequenies (Pearson, 1929; Simmons and Breuer, 1962). Marginal. inrement analysis of the sales of small (<493 mm) blak drum sampled in Georgia suggested annulus formation during February April (Musi and Pafford, 1984). However, marginal inrement analysis of the sales of older fish has not revealed an annual periodiity in growth hek formation (Rihards, 1973; Cornelius, 1984), possibly due to the diffiulty of reading the heavily alified sales taken from blak drum larger than 600 mm (Pearson, 1929). Based on data gathered by using an analog triangulation proedure for estimating von Bertalanffy growth equation parameters, Rihards (1973) hypothesized that blak drum sales form two 3 Murphy, M.D., and R. G. Taylor. Florida Marine Researh Institute, Department of Natural Resoures, 100 Eighth Ave. S.E., St. Petersburg, FL 33701, unpubl. data. e 0.8 E ~ z w ::; w :g:.j < z ~ 0.2 < ::; COLLECTION MONTH Figure 2. Monthly mean marginal inrement for P. romis with 1-4 annuli. marks per year after approximately their fourth mark. However, this onlusion has not been verified. Average observed lengths for males and females were not signifiantly different (p>0.05) for ages 1-4 (Table 3). Although sample sizes for males and females at older ages were too small to test for statistial differenes, both sexes appeared to reah similar observed maximum lengths (females, 1275 mm; males, 1257 mm). Therefore, age and length data for both sexes were pooled for growth analysis. The growth rate for blak drum ages 1-3 was about 100 mm yr-1, then slowed gradually to mm yr- 1 for ages (Table 3). Mean bakalulated lengths for ages 1-4 were similar to the average observed lengths at those ages (Table 3). Growth rates were predited well by the von Bertalanffy growth model with parameter estimates ( ± standard error) of L 00 = 1172 ( ± 9), K=0.124 (±0.003), and t 0 = (± 0.08). In general, growth rates determined by using the von Bertalanffy growth model were similar to those determined from observed mean lengths (Fig. 3). The two age 6 fish olleted appeared to be anomalously large. Growth of adult blak drum (Table 4) has been desribed in Texas, Georgia, and Virginia (Pearson, 1929; Simmons and Breuer, 1962; Rihards, 1973; Cor- DOI: /negs

8 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Reprodution and growth of blak drum 133 nelius, 1984; Musi and Pafford, 1984). Estimates of lengths-at-age of blak drum in Texas waters were generally similar to our predited sizes for fish in northeast Florida waters (Pearson, 1929; Simmons and Breuer, 1962); however, bak-alulated lengths for south Texas blak drum were smaller after age 4 (Cornelius, 1984). In Georgia, blak drum ages 2-6 were similar in lengths to drum in northeast Florida, but were apparently smaller after age 6 (Musi and Pafford, 1984). Bak-alulated lengths for 1-yearold Virginia blak drum were smaller than those determined for northeast Florida blak drum the same age. Lengths were similar for 2-year-old drum from both loations, but lengths for subsequent ages were muh greater for blak drum from Virginia, even without a "orretion" for the possible formation of two rings per year after age 4 (Rihards, 1973). Parameters of the von Bertalanffy growth model for blak drum have been estimated for sale-aged fish from Virginia (Rihards, 1973) and by using tag-return data from Texas (Doerzbaher eta!., 1988). Rihards' (1973) parameter estimates, made with the assumption that two sale rings are formed per year after age 4, were K=0.158 and Loo=147.4m FL. These estimates predit muh faster 1200 e woo. i= 800 (!) ffi..l 600..l ~ ~ o AVERAGE OBSERVED o PREDICTED. USING!,= 1172 ~ l-e 0.12(1 +13)) AGE (YEARS) Figure 3. Average observed and predited growth of P. romis in northeast Florida..:.: (.) ~. <1l :2 0 u:: ~.. t en en :5 ~ <1l 0. en (ij : 2 (.) :2 0 (.) '2f. l{) Ol :5 ~ E. en.. OJ (ij 2 "0 : "0. "0 <1l "0 1il ::J (.). (ij ~ (.) <1l -i5~ roo.c(") -Q'"O : <ll ~:).en OLC) T"' g>:)...,... ~.,.!. <{ en C")g> ~ E.g 2 l-"0 -+ = Published by The Aquila Digital Community,

9 Gulf of Mexio Siene, Vol. 10 [1988], No. 2, Art Murphy, M.D., and R. G. Taylor Table 4. Total length (mm) at age (yrs) for blak drum (taken from the literature). Literature values of fork length were onverted to total length using equation in Table 5. Symbols are 1/f = length frequeny, bak-al. = bak-alulated lengths, and v.b. eq. = von Bertalanffy equation Age Study Pearson (1929); 1/f and sales Simmons and Breuer (1962); 1/f and tag returns Rihards (1973) (unorreted); bak-al Rihards (1973) (orreted); predited, v.b. eq. Musi and Pafford (1984); bak-al Cornelius (1984); bak-al. This study; predited, v.b. eq growth rates for fish after age 2 than we found in this study. The greater estimate of Loo in Virginia may reflet the ommon observation that larger fish are more available in the more northerly part of their range, as has been suggested for menhaden, Brevoortia tyrannus (Niholson, 1971); weakfish, Cynosion regalis (Wilk, 1979); and red drum Siaenops ae/latus (Welsh and Breder, 1923). Parameter estimates (standard error) for the von Bertalanffy model for blak drum growth in Texas, L 00 = 798 (42) mm and K = (0.027), suggested faster relative growth but to a smaller maximum size than we found for fish in Florida (Doerzbaher et at., 1988). The limited length distribution (98% of data from fish mm TL) of tag returns available for growth analysis from the Texas tagging program may restrit the effetive fit of their growth model to only fish under about 800 mm. Assuming that all opaque bands are DOI: /negs annuli, the observed maximum age for blak drum off the northeast oast of Florida is 58 years. The previous maximum age reported for blak drum was 35 years (Rihards, 1973). A maximum opaque band ount of 46 has been reported for large blak drum (1,132 rnm) sampled off Georgia (Musi and pafford, 1984). Several drum tagged in Texas bays have been reaptured after 10 to 12 years of freedom (Green, 1986), whih onfirms a life span of at least 12 years. Weight-Length and Length-Length Relations Parameter estimates of allometri weight-length relationsh i s for males and females were not signifiantly different (p>0.05 between both "a's" and "b's"); therefore, relationships were alulated after data for both sexes were pooled (Table 5). The pooled estimate of "b" was not signifiantly different (p>0-.05) from 3 therefore blak drum growth is ' ' 8

10 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Reprodution and growth of blak drum 135 Table 5. Weight-length and length-length regressions of blak drum, with supporting statistis. All reg res sions were signifiant (p<0.05). Measures are grams and millimeters. Abbreviatins are W = whole weight, FL = fork length, TL = total length, and SL = standard length. Equation Sample Total Length r' Size Range Total SSy X y Correted Mean - - w = 1.16x1o-' TL 3 ' X FL = TL x TL = FL X SL = TL X TL = SL X FL = SL X SL = FL X isometri. Weight-length regressions for blak drum have been alulated for adult populations along most of its range within the United States. Blak drum from north east Florida and South Texas appear to be, on the average, a similar weight at a given length; blak drum in Louisiana, Texas, and Virginia are lighter, and those sampled in Georgia are heavier (Table 6). FISHERIES IMPLICATIONS Biologial harateristis of blak drum suggest that it is a poor andidate for an intensive or even moderate fishery. Their apparent life span of more than 50 years implies an extremely low natural mortality rate that suggests that, under equilibrium onditions, little surplus pro dution is available for fishery yield. Low natural mortality and relatively slow growth suggest that at low levels of exploitation blak drum populations ould be depleted by growth overfishing, even when size at first apture is quite large. Also, a moderate level of fishing ould severely redue blak drum abun dane and juvenese the 50 year-lass Table 6. Predited weights (grams) for blak drum of given lengths, based on length-weight relations from the literature. FL onverted to TL using equation in Table 5. Total Length (mm) Study I Area Cornelius (1984); 391 3,241 11,176 26,899 South Texas Rihards (1973); 359 3,071 10,719 26,052 Virginia Musi and Pafford (1984); 445 3,748 13,041 31,585 Georgia Hein eta/. (1980); 348 2,729 9,102 21,396 Louisiana Harrington et at. (1979); 378 3,029 10,225 24,245 Texas This study; 402 3,318 11,399 27,364 FiJorida Published by The Aquila Digital Community,

11 136 Murphy, M. D., and R. G. Taylor Gulf of Mexio Siene, Vol. 10 [1988], No. 2, Art. 6 age struture that makes up the spawning population. It has been hypothesized that a large number of year lasses in a spawning population ould be an adaptation that ensures an adequate spawning population, even in the fae of flutuating reruitment (Murphy, 1968; Leaman and Beamish, 1984). Therefore, juvenesed blak drum spawning stoks would probably be more suseptible to reruitment overfishing. Behavioral harateristis of blak drum also make them highly suseptible to fishing. In the spring, adult blak drum ongregate in large shools often assoiated with spawning. These fish an easily be aptured while ongregated, espeially by enirling gear (run-around gill nets, trammel nets, purse seines). Off the Gulf oast of Florida, adult blak drum purseseine athes have been estimated to be as great as 120,000 lbs 4 Off northeast Florida, shrimp trawlers oasionally make large athes of adults during the spring. ACKNOWLEDGMENTS We wish to thank fishermen who ontributed speimens for sampling, espeially Darin Harrell, Gene and Marvin Nipper, Alan Bond, and the personnel at Atlanti Seafood Bait and Takle. Florida Marine Researh Institute sientists who helped sample fish inluded John Darove, Mihael Mithell, Glenn Parsons, Lewis Bullok, and Robert M Mihael. Histologial assistane was provided by Ruth Reese and I Iiana Quintero. We espeially thank Judith Leiby, Llyn Frenh, and Vivien Smith for their editorial assistane. Marjorie Myers skillfully typed all drafts of this manusript. 4 Beverly Roberts, Florida Marine Researh Institute, Department of Natural Resoures, 100 Eighth Ave. S.E., St. Petersburg, FL 33701, personal omm. DOI: /negs LITERATURE CITED Bagenal, T. B., and F. W. Tesh Age and growth. In T. B. Bagenal, ed. Methods for assessment of fish prodution in fresh waters. Balkwell Si. Publ., Oxford. pp Cody, T. J., K. W. Rie, and C. E. Bryan Distribution and gonadal development of blak drum in Texas gulf waters. Tex. Parks Wildl. Dep., Manage. Data Ser. 72:1-16. Cornelius, S. A Contribution to the life history of blak drum and analysis of the ommerial fishery of Baffin Bay. Volume II. Teh. Bull. 6. Caesar Kleberg Wildl. Res. lnst. 53 p. Doerzbaher, J. F., A. W. Green, A. W. Osburn, and G. C. Matlok A temperature ompensated von Bertalanffy growth model for tagged red drum and blak drum in Texas bays. Fish. Res. 6: Fontenot, B. J., Jr., and H. E. Rogillo A study of estuarine sportfishes in the Biloxi marsh omplex, Louisiana. La. Dep. Wildl. Fish., Fish. Bull. 3: Fouher, R. P., and R. J. Beamish Prodution of nonviable ooytes by Paifi hake (Mer/uius produtus). Can. J. Fish. Aquat. Si. 37: Frisbie, C. M Young blak drum, Pogonias romis, in tidal fresh and brakish waters, espeially in the Chesapeake and Delaware Bay areas. Chesapeake Si. 2(1-2): Green, L. M Fish tagging on the Texas oast, Tex. Parks Wildl. Dep., Manage. Data Ser. 99: Grier, H. J Cellular organization of the testis and spermatogenesis in fishes. Am. Zoo I. 21: Harrington, R. A., G. C. Matlok, and J. E. Weaver Standard-total length, total length-whole weight and dressedwhole weight relationships for seleted speies from Texas bays. Tex. Parks 10

12 Murphy and Taylor: Reprodution and Growth of Blak Drum, Pogonias romis, in Northe Reprodution and growth of blak drum 137 Wildl. Dep. Teh. Ser. 26:1-6. Hein, S., C. Dugas, and J. Shepard Total length-standard length and length-weight regressions for spotted seatrout, Cynosion nebu/osus; red drum, Siaenops ae/latus; and blak drum, Pogonias romis, in Southentral Louisiana. La. Dep. Wildl. Fish. Teh. Bull. 31: Humason, G. L Animal tissue tehniques. W. H. Freeman and Company, San Fransiso, CA. 641 p. J.annke, T. E Abundane of young siaenid fishes in Everglades National Park, Florida, in relation to season and other variables. Univ. Miami Sea Grant Program Sea Grant Teh. Bull. No. 11: Joseph E. B., and R. W. Yerger The fishes of Alligator Harbor, Florida, with notes on their natural history. Fla. State Univ. Stud. No. 22: Kilby, J.D The fishes of two Gulf oastal marsh areas of Florida. Tulane Stud. Zool. 2(8): Leaman, B. M., and R. J. Beamish Eologial and management impliations of longevity in some northeast Paifi ground fishes. Int. North Pa. Fish Comm. Bull. 42: Murphy, G. I Patterns in life history and the environment. Am Nat. 102(927): Musi, J. F., and J. M. Pafford Population dynamis and life history aspets of major marine sportfishes in Georgia's oastal waters. Ga. Dep. Nat. Resour. Coastal Div. Contrib. Ser. 38: Niholson, W. R Coastal movement of Atlanti menhaden as inferred from hanges in age and length distribution. Trans. Am. Fish. So. 100(4): Pearson, J. C Natural history and onservation of redfish and other ommerial siaenids on the Texas oast. Bull. U.S. Bur. Fish. XLIV: Reid, G. K., Jr An eologial study of the Gulf of Mexio, in the viinity of Cedar Key, Florida. Bull. Mar. Si. Gulf Caribb. 4(1):1-94. Rihards, C. E Age, growth and distribution of the blak drum (Pogonias romis) in Virginia. Trans. Am. Fish. So. 1 02(3): Ross, J. L., J. S. Pavela, and M. E. Chittenden, Jr Seasonal ourrene of blak drum, Pogonias romis, and red drum, Siaenops oel/atus, off Texas. Northeast Gulf Si. 6(1): SAS Institute, In SAS user's guide: basis Edition, Cary, North Carolina. SAS lnst., In. 923 p. Simmons, E. G., and J.P. Breuer A study of redfish, Siaenops oellata Linaeus, and blak drum, Pogonias romis Linneaus. Publ. lnst. Mar. Si. Univ. Tex. 8: Springer, V. G., and K. D. Woodburn An eologial study of the fishes of the Tampa Bay area. Fla. State Board Conserv. Mar. Lab. Prof. Pap. Ser. No. 1: Vaughan, D. S., and P. Kaniruk An empirial omparison of estimation proedures for the von Bertalanffy growth equation. J. Cons. Cons. Int. Explor. Mer. 40: Wallae, R. A., and K. Selman Cellular and dynami aspets of ooyte growth in teleosts. Am. Zool. 21: Welsh, W. W., and C. M. Breder, Jr Contributions to the life histories of Siaenidae of the eastern United States oast. Bull. U.S. Bur. Fish. 39: Wilk, S. J Biologial and fisheries data of weakfish, Cynsion rega/is (Blok and Shneider). Northeast Fish. Center, Sandy Hook Lab., NOAA Teh. Ser. Rep p. Published by The Aquila Digital Community,