reproduction megalopsatlanticus

BULLETIN OF MARINE SCIENCE 61(2) 271ndash285 1997

271

REPRODUCTION OF TARPON MEGALOPS ATLANTICUS FROMFLORIDA AND COSTA RICAN WATERS AND NOTES ON THEIR

AGE AND GROWTH

Roy E Crabtree Edward C Cyr Didiher Chacoacuten ChaverriWilliam O McLarney and John M Dean

ABSTRACTWe examined 1469 tarpon ranging 102-2045 mm fork length (FL) that were collected

in South Florida waters and 217 tarpon ranging 880-1860 mm FL that were collected inCosta Rican waters from 1989 to 1994 Among the Florida tarpon gonads of 737 fishwere examined histologically and gonadosomatic indices were calculated for 409 tar-pon Among Costa Rican tarpon gonads of 202 tarpon were examined histologicallyand gonadosomatic indices were calculated for 178 tarpon Florida fish were signifi-cantly larger than those from Costa Rica and sexually mature females were significantlylarger than sexually mature males in both areas All Florida males were sexually matureby 1175 mm FL and only one smaller male (901 mm) was mature The smallest sexu-ally mature Florida female was 1285 mm FL and all larger females except one weresexually mature Only one Florida tarpon a 7-yr-old female younger than 10 yrs wassexually mature all tarpon older than 10 yrs were sexually mature In Costa Rica onlyone immature female (880 mm FL) was examined all other females (1126-1860 mmFL) were sexually mature All Costa Rican males examined (880-1550 mm FL) weresexually mature Florida tarpon spawned during April-July and by August most femaleswere spent or recovering Spawning in Costa Rican waters was not seasonal and repro-ductively active females were caught during all months Fecundity estimates for Floridatarpon ranged 45-207 million oocytes and had a significant positive relationship withfish weight Otoliths of tarpon from Costa Rican waters were difficult to read Weexamined thin-sectioned otoliths (sagittae) from 194 Costa Rican tarpon but could esti-mate ages for only 87 fish (45) Costa Rican tarpon are long-lived and reach a maxi-mum age of at least 48 yrs Most (74) tarpon caught in Costa Rica that we aged were 15to 30 yrs old

Tarpon Megalops atlanticus are large migratory elopomorph fish that frequent coastaland inshore waters of the tropical and subtropical Atlantic Ocean In the western Atlan-tic tarpon regularly occur from Virginiarsquos eastern shore to central Brazil and throughoutthe Caribbean Sea and the Gulf of Mexico (Wade 1962 Hildebrand 1963 de Menezesand Paiva 1966 Zale and Merrifield 1989) In parts of Central America and southFlorida tarpon are the basis of economically important recreational fisheries In Floridathe fishery is intensely regulated and anglers are required to purchase a $50 permit be-fore harvesting a fish Since the establishment of the permit system in 1989 the harvestof tarpon in Florida has declined to less than 100 fish per yr and the fishery is nowmostly catch-and-release Tarpon occur in a variety of habitats ranging from freshwaterlakes and rivers to offshore marine waters but large tarpon targeted by Floridarsquos fisheryare most abundant in estuarine and coastal waters In Florida the fishery is seasonalmost tarpon are caught during May-July although some fish are caught in all monthsThe Costa Rican fishery is located principally in the Rio Colorado region where fishingoccurs year-round both in coastal waters and in the river Most of the tarpon fishing in the

272 BULLETIN OF MARINE SCIENCE 61(2) 271ndash285 1997

area is catch-and-release and anglers usually fish with professional guides employed bylocal fishing lodges

Little information is available on the reproductive biology of tarpon Chacoacuten Chaverriand McLarney (1992) documented the occurrence of larvae and juveniles during July-November in Costa Rican inshore waters No other information on reproduction or ageand growth exists for the area More is known about the biology of tarpon from otherareas Crabtree et al (1992) and Crabtree (1995) described the early life history of tarponfrom Florida waters and found that spawning is seasonal and occurs offshore during May-August Onshore transport of larvae is episodic and affected by environmental events(Shenker et al 1995) Breder (1944) examined gonads of tarpon from Florida waters butdid not adequately describe either temporal spawning patterns or age and length at matu-rity Crabtree et al (1995) described the age and growth of tarpon from Florida watersand found that tarpon are long-lived and can reach ages greater than 50 yrs De Menezesand Paiva (1966) examined gonads from tarpon caught off the northeast coast of Braziland found that reproduction occurs during October-January In this paper we describeseasonal spawning patterns length at sexual maturity and fecundity of tarpon from SouthFlorida and from the Rio Colorado area of Costa Rica Age estimates are presented fortarpon from Costa Rican waters

MATERIALS AND METHODS

We obtained Florida tarpon from a variety of sources from April 1988 to November 1993 Mostlarge fish (gt1100 mm FL) were obtained from taxidermists in Fort Myers and Fort Lauderdale andwere caught in either the Florida Keys or Boca Grande Pass on Floridarsquos Gulf coast (26deg 43 N 82deg16 W) A second source of large fish was tournaments held in the Keys Boca Grande Pass and theTampa Bay area (27deg 40 N 82deg 35 W) All large tarpon were caught with hook-and-line gearSmall Florida tarpon (lt1100 mm FL) were taken with cast nets hook-and-line gear electroshockertrammel nets and gill nets at various locations Tarpon in Costa Rica were caught with hook-and-line gear during normal fishing operations conducted by fishing lodges located in the Rio Coloradoarea on the Caribbean coast of northeastern Costa Rica from May 1989 to January 1994

Standard length (SL) fork length (FL) and total length (TL) were measured to the nearest milli-meter (mm) All lengths reported are fork lengths Large tarpon (gt1100 mm) were weighed to thenearest 05 kg and smaller tarpon were weighed to the nearest gram Otoliths (sagittae) wereremoved cleaned with bleach (525 sodium hypochlorite) and rinsed first in water and then in95 ethanol Otoliths were stored dry or in 95 ethanol until sectioned Sex gonad conditionand gonad weight in grams were recorded Gonad samples were removed from the fish and pre-served in 10 buffered Formalin they were then soaked in water for 1 h and stored in 70 ethanolLength-weight regressions were calculated by linear regression of log

10-transformed data and were

compared with a t-test (Zar 1984)Histological sections of gonads from 737 Florida tarpon and 202 Costa Rican tarpon were pre-

pared and assessed for reproductive state Initially gonad sections were taken from all tarponAfter examining histological sections from 168 Florida tarpon smaller than 400 mm we concludedthat we could not reliably sex small tarpon and subsequently processed sections only from fishlarger than 400 mm Gonad samples were processed histologically with a modification of theperiodic acid Schiff rsquos stain for glycol-methacrylate sections with Weigertrsquos iron-hematoxylin as anuclear stain and metanil yellow as a counterstain (Quintero-Hunter et al 1991) Gonads wereclassified based on the modified maturity criteria of Murphy and Taylor (1990) in Table 1 Thepresence of widespread atresia in inactive ovaries was interpreted as evidence of past reproductive

273CRABTREE ET AL TARPON LIFE HISTORY

activity The presence of postovulatory follicles (POF) was interpreted as evidence of recent spawn-ing Tarpon with gonads in maturity classes 3-8 were considered sexually mature

Monthly mean oocyte diameters and gonadosomatic indices (GSI) were plotted to show sea-sonal reproductive patterns Oocyte size was determined by measuring the minimum and maxi-mum diameter of each oocyte within a random subsample of 100 oocytes from each histologicalsection and then averaging the two measurements Oocytes were measured only if the nucleus wasvisible indicating that the section was approximately through the middle of the oocyte Measure-ments were made with a digital image-processing system In addition minimum and maximumdiameters of 10 of the largest oocytes in each histological section were measured to estimate meanmaximum oocyte diameter GSIs were calculated for 409 sexually mature Florida tarpon and 178sexually mature Costa Rican tarpon as

GSI = (GW(TW-GW))100

where GW = total gonad weight (g) and TW = total fish weight (g)Total fecundity (the standing stock of advanced yolked oocytes) of 32 Florida tarpon was esti-

mated gravimetrically from subsamples taken from various locations in each ovary Twenty-six

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fish were subsampled from anterior middle and posterior portions of each ovary to evaluate spa-tial variations in oocyte size within the ovary and between ovaries Subsamples were preserved in10 Formalin and later transferred to 70 ethanol Subsamples of ovary containing approxi-mately 1000-1500 late-vitellogenic oocytes were weighed to the nearest 001 mg and total fecun-dity was calculated based on the mean number of oocytes per gram of ovary Gonads from all fishsampled for fecundity were in maturity classes 4 or 5 and only late-vitellogenic oocytes gt05 mmin diameter were counted

Undamaged otoliths from Costa Rican tarpon were weighed to the nearest 001 mg and weightswere compared to those of Florida tarpon reported by Crabtree et al (1995) Weights of left andright otoliths were not significantly different (paired t-test n = 33 t = 08237 P = 0416) so otolithweights were pooled for analysis If both left and right otolith weights were available for an indi-vidual fish the mean of the two weights was calculated Linear regressions were fit to log

10-

transformed otolith weight and length data and were compared with a t-test (Zar 1984)We prepared otoliths of 194 Costa Rican tarpon for age estimation following the methods of

Crabtree et al (1995) Annuli were counted three times by each of two independent readers usingcompound microscopes Because there was no significant difference between the mean counts ofeach reader (paired t-test n = 87 t = 19724 P = 0052) ages were pooled for analysis Annuluscounts for individual otoliths usually showed some level of variation among readings We estab-lished criteria for accepting or rejecting individual otoliths by calculating a coefficient of variation(CV) = (sy x 100) where s = the standard deviation of counts for a given otolith and y = the meanannulus count for a given otolith We allowed a maximum CV of 1216 following Crabtree et al(1995)

RESULTS

The 1469 Florida tarpon we examined ranged 102-2045 mm in length the 217 CostaRican tarpon we examined ranged 880-1860 mm in length Among Florida tarpon 740(504) of the fish we examined were young-of-the-year or 1-yr-old fish (lt400 mm)Body size in tarpon was sexually dimorphic Sexually mature Florida females (gonadclass 3 or greater) had a significantly larger mean fork length (1681 mm SD = 1393 n= 299) and attained a larger maximum length (2045 mm) than sexually mature Floridamales (mean = 1450 mm SD = 1317 maximum length = 1884 mm n = 108 t-test t =14991 df = 405 P lt 0001 Fig 1) Sexually mature Costa Rican females had a signifi-cantly larger (t-test t = 12694 df = 200 P lt 0001) mean fork length (1456 mm SD =1140 n = 113) and attained a larger maximum length (1860 mm) than sexually matureCosta Rican males (mean = 1254 mm SD = 1103 maximum length = 1550 mm n =89 Fig 1) Standard length fork length and total length relationships for Costa Ricantarpon are presented in Table 2 those for Florida tarpon were presented by Crabtree et al(1995) The slopes of the length-weight equations for male and female Costa Rican tar-pon were significantly different (t-test t = 2323 df = 204 P = 0011) Costa Ricanfemales larger than about 1150 mm were usually heavier than males of the same length

Tarpon from Costa Rican waters were smaller than tarpon from Florida waters (Fig 1)The largest Florida males (upper quartile = 1524 mm largest = 1884 mm) and females(upper quartile = 1776 mm largest = 2045 mm) were larger than the largest males (up-per quartile = 1320 mm largest = 1550 mm) or females (upper quartile = 1525 mmlargest = 1860 mm) we observed in Costa Rica Furthermore the mean length of sexu-ally mature Florida males (1450 mm) was significantly larger than that of sexually ma-ture Costa Rican males (1254 mm t-test t = 11157 df = 195 P lt 0001) and the meanlength of sexually mature Florida females (1681 mm) was significantly larger (t-test t =


15311 df = 410 P lt 0001) than that of sexually mature Costa Rican females (1456mm)

We were usually unable to determine the sex of small tarpon (lt400 mm) Only 11 of179 (61) Florida fish ranging 124-400 mm in length and examined histologically couldbe sexed The smallest female that we could sex was 343 mm in length and the smallestmale was 237 mm The smallest female that had primary oocytes was 523 mm Someimmature fish without primary oocytes or signs of spermatogenesis were sexed based ongeneral gonad morphology Ovaries had many finger-like lobes that contained only oo-gonia in most class-1 ovaries but they occasionally contained primary oocytes that hadlittle cytoplasm and a nucleus containing a large basophilic nucleolus In contrast testeswere typically straight along the distal edge and had fewer invaginations

The smallest sexually mature Florida male in our sample was 901 mm in length thenext-smallest mature male was 1175 mm in length and all larger males were sexuallymature The smallest sexually mature Florida female was 1285 mm in length and alllarger females except one 1368-mm female were mature Only one Florida tarpon anexceptionally large 7-yr-old female (1370 mm) younger than 10 yrs was sexually ma-ture All Florida tarpon older than 10 yrs were sexually mature All Costa Rican malesexamined (880-1550 mm) were sexually mature One immature developing Costa Ricanfemale (880 mm 7 yrs old) was examined all other females (1126-1860 mm) weresexually mature The youngest sexually mature male in our Costa Rican sample was 7 yrsold the youngest sexually mature female was 12 yrs old

Small previtellogenic oocytes (002-02 mm diameter) were present in all tarpon withdeveloping ovaries (Fig 23) Females with mature ovaries had a second class ofvitellogenic oocytes ranging 05-09 mm in diameter The largest oocytes observed were

Figure 1 Length-frequency distributions of sexually mature male and female tarpon from Floridaand Costa Rican waters


those with migrating nuclei and diameters of approximately 09 mm and a few atretichydrated oocytes with diameters of approximately 10 mm Only a few atretic hydratedoocytes were observed in spent or partially spent fish and we did not examine any spawningfemales containing many hydrated oocytes

Reproduction in Florida appeared to be seasonal but because Floridarsquos tarpon fisheryis seasonal we were unable to examine any mature fish collected during October-Janu-ary More than 80 of the females examined during April-June contained maturingvitellogenic oocytes (gonad class 4 Fig 4) Tarpon with migrating nuclei (n = 3) atretichydrated oocytes (n = 2) and partially spent females (n = 16) with both maturingvitellogenic oocytes and POFs were found during May-August During July spent andrecovering females increased in frequency and by August represented more than 90 ofthe females (Fig 4) Mean diameters of the largest oocytes present in individual ovariespeaked during May and were much lower in February and August (Fig 5) Mean GSIswere highest during April-July for both males and females (Fig 6) The decline in femaleGSIs and mean diameters of the largest oocytes during July and August correspondedwith the increased percentage of spent and recovering fish during late summer (Fig 4)

Figure 2 Oocyte diameter-frequency distributions for female tarpon from Florida waters


Spawning in Costa Rican waters was not seasonal Males with mature testes werepresent in all months except July August and December when we did not collect anymales Our sample sizes for these months were low because most of the fishing lodgeswere closed during these months Most males had mature testes only one male withmaturing testes and two males with recovering testes were found Females with matureripe partially spent or spent ovaries were captured in every month (Fig 4) Partiallyspent females with POFs and a second batch of maturing vitellogenic oocytes 03-07 mmdiameter (Figs 37) were present in all months except June and August when samplesizes were low Only four females with recovering ovaries were found Most females hadeither mature ovaries (35) and contained vitellogenic oocytes of 06-09 mm diameter(Fig 3) or were partially spent (22) or spent (33) and contained many POFs Bothmean monthly diameters of the 10 largest oocytes present in ovaries (Fig 5) and GSIs hadno seasonal trends (Fig 6)

Total fecundity estimates for Florida tarpon ranged 45-207 million oocytes and had asignificant positive relationship with fish weight (Table 2) Oocyte development amongareas within the ovary was homogeneous We used a two-factor analysis of variance to

Figure 3 Oocyte diameter-frequency distributions for female tarpon from Costa Rican waters


compare oocyte densities with side and position as the effects The number of latevitellogenic oocytes per gram of wet ovary weight was not significantly different betweenleft and right ovaries (ANOVA df = 1 P = 0988) or among subsamples from anteriormiddle or posterior sections of the ovary (ANOVA df = 2 P = 0427) Furthermore wefound no significant interaction between side and position from which subsamples weretaken (ANOVA df = 2 P = 0999) Weights of left and right ovaries from mature (gonad

Figure 4 Monthly distributions of gonad classes for sexually mature female tarpon from Floridaand Costa Rican waters


class 4) females were not significantly different (paired t-test n = 195 t = 1727 P =0086) but left testes from mature (gonad class 4) males were significantly larger thanright testes (paired t-test n = 94 t = 4912 P lt 0001)

Of 194 otoliths from tarpon collected in Costa Rican waters and examined for ageestimation 95 (49) were judged unreadable by one or both readers and were not as-signed ages and an additional 12 (6) otoliths were rejected for having a high variationamong reads (CV ge 1216) thus 87 (45) otoliths were accepted for age estimatesThe length-frequency distribution of fish whose otoliths were rejected because they wereunsuitable for age estimation was not significantly different from the length-frequency

Figure 5 Monthly mean diameters of the largest oocytes present in ovaries with standard errorsand number of fish examined for sexually mature female tarpon from Florida and Costa Ricanwaters


distribution of all fish examined (Kolmogorov-Smirnov two-sided test statistic = 0397P = 0997)

Tarpon from Costa Rican waters are long-lived the oldest fish we examined were a 47-yr-old male (1301 mm) and a 47-yr-old female (1530 mm) The youngest fish examinedwere a 7-yr-old male (1030 mm) and a 7-yr-old female (880 mm) There was no signifi-cant difference in the average age of males (229 yrs) and females (224 yrs t-test t =0106 df = 84 P = 0779) Most (74) tarpon caught in this study were 15 to 30 yrs old

We weighed 96 otoliths from Costa Rican tarpon (range = 0147-0558 g mean = 0351g SD = 00746) in order to compare them with those from Florida tarpon (Crabtree et al1995) The otolith-weight frequency distribution for sexually mature Costa Rican tarponwas not significantly different from that of sexually mature Florida tarpon (Kolmogorov-Smirnov two-sided test statistic = 0837 P = 0496 Fig 8) Furthermore the mean otolithweight for sexually mature Costa Rican tarpon (0353 g) was not significantly differentfrom that of sexually mature Florida tarpon (0352 g t-test t = 0159 df = 376 P =0874) and the weight range of otoliths from sexually mature Florida tarpon (0180-

Figure 6 Monthly mean GSI with standard errors and sample sizes for sexually mature female andmale tarpon from Florida and Costa Rican waters


0695 g) included that of otoliths from Costa Rican tarpon (0208-0558 g) Weights ofotoliths from Costa Rican tarpon had a significant positive relationship with fork length(Table 2)

DISCUSSION

Tarpon from Florida waters appeared to attain larger sizes than those from Costa Ricanwaters (Fig 1) but because we relied on anglers to provide fish our data are probablybiased Most Florida fish were caught during tournaments or were kept as trophies to bemounted by a taxidermist presumably in both situations anglers selectively kept largerfish Sometimes Florida tournaments imposed minimum size requirements of up to 50kg Since males were typically smaller than females and rarely exceeded 45 kg oursamples from the Florida recreational fishery contained roughly twice as many femalesas males In Costa Rica anglers kept tarpon as trophies or because they wished to partici-pate in our research program We assume that anglers in Costa Rica like those in Floridaselectively kept larger fish but we do not know the extent of this bias in each data set Asin Florida we examined more Costa Rican females than males probably a result of thebias towards large fish but the difference was less than in Florida It is possible thatbehavioral differences between anglers from the two areas affected our comparisons ofthe size of tarpon from the two areas

Figure 7 A histological section from an ovary from a 1498-mm-FL tarpon from Costa Ricanwaters showing vitellogenic oocytes (VO) and postovulatory follicles (POF) Scale bar = 200 microns


In Costa Rican waters tarpon reached sexual maturity at a smaller size than tarponfrom Brazilian or Florida waters Costa Ricarsquos tarpon fishery principally targeted sexu-ally mature individuals We examined only a single immature Costa Rican fish and wereunable to estimate length and age at sexual maturity however the scarcity of immaturefish in our collections suggests that sexual maturity was attained at less than 880 mm bymales and at less than 1126 mm by females In Florida where more than 50 of oursample consisted of immature fish the smallest mature male examined was 901 mm andthe smallest mature female examined was 1285 mm Breder (1944) reported that thesmallest ripe female he observed off Floridarsquos Gulf coast was 1398 mm but he suggestedthat female tarpon probably attain sexual maturity at about 1200 mm De Menezes andPaiva (1966) reported that tarpon from Brazilian waters begin to attain sexual maturity atlengths of 950 mm for males and 1250 mm for females Unfortunately because rela-tively few fish in the critical transitional length range of 800-1200 mm have been exam-ined from any area we are unable to accurately estimate the length or age at which 50of the tarpon population reaches sexual maturity

Tarpon from Costa Rican waters showed no seasonal pattern of reproduction unliketarpon from other areas In Florida tarpon gonadal development was seasonal and peakedduring May-July By August most females were spent or recovering Breder (1944)examined tarpon from Floridarsquos Gulf coast and reported that spawning occurs at leastduring May-July but he presented little data to support this assertion Large Floridatarpon were not available during all months so our evidence for seasonal spawning basedon the examination of gonads is equivocal however other evidence also suggests sea-sonal spawning in Florida waters Back-calculated hatching dates of tarpon larvae fromotolith microstructure analysis and larval growth rates suggest spawning during May-August off Floridarsquos Gulf coast (Crabtree et al 1992 Crabtree 1995) Smith (1980)

Figure 8 Otolith weight-frequency distributions for sexually mature tarpon from Florida and CostaRican waters


collected tarpon larvae from the Gulf of Mexico and suggested that spawning occursduring June-July

The presence of partially spent females with ovaries containing POFs and advancedvitellogenic oocytes (Fig 7) in both Florida and Costa Rican waters suggests that tarponare multiple spawners In Costa Rica partially spent females were more common than inFlorida and made up 22 of the females we examined (Fig 4) Recovering females werenot abundant (n = 4) in Costa Rican waters suggesting that females spawned repeatedlythroughout the year and had no extended period of inactivity In contrast 74 of thesexually mature Florida females examined near the end of the Florida spawning season(August) were recovering Spent females comprised 33 of our Costa Rican sampleThese females often contained POFs suggesting recent spawning but did not have anadditional batch of maturing vitellogenic oocytes Spent females either quickly devel-oped a batch of maturing vitellogenic oocytes or left the Rio Colorado area soon afterspawning for a period of recrudescence elsewhere In Florida the number of recoveringfemales was similar to the number of spent females but this was not true in Costa RicaWe did not examine any fully hydrated females and were thus unable to estimate batch

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fecundity If tarpon are multiple spawners our estimate of total fecundity for Floridatarpon may not accurately represent total annual egg production

We did not validate the annual nature of annulus formation for Costa Rican tarpon Weassumed that the annuli we counted on otoliths of Costa Rican tarpon were annual marksbased on the similar appearance of these annuli to those of Florida tarpon Crabtree et al(1995) validated the annual nature of annulus formation for 12 out of 18 oxytetracycline-marked otoliths from Florida tarpon that were 4-9 yrs old Otoliths from six fish wereeither unreadable or did not form the expected number of annuli The annual nature ofannulus formation for older tarpon (gt 9 yrs) has not been validated

Otoliths of tarpon from Costa Rican waters were more difficult to interpret than thoseof tarpon from Florida waters We rejected a relatively high percentage (55) of theotoliths from Costa Rican tarpon as unreadable Rejected otoliths had irregular and poorlydefined features which precluded our making precise annulus counts Crabtree et al(1995) were unable to read 206 of the otoliths of tarpon from Florida waters The moretropical environment of Costa Rica and the absence of seasonal reproduction probablycontributed to the less seasonal nature of otolith growth in Costa Rican fish than in tarponfrom more temperate Florida waters

In Costa Rican waters tarpon attained ages similar to those of tarpon from Floridawaters The oldest Costa Rican male and female we examined were each estimated to be47 yrs old Crabtree et al (1995) reported similar maximum ages for tarpon from Floridawaters The oldest Florida male was 43 yrs old and the oldest female was 55 yrs oldCrabtree et al (1995) showed otolith weight to be closely related to age for Florida tar-pon The similarity between otolith weights of Costa Rican tarpon and those of Floridatarpon (Fig 8) supports our view that tarpon from the two areas attain similar ages

In conclusion the differences in overall size and size at sexual maturity of tarpon fromCosta Rican and Florida waters suggest limited movement of fish between the two areasAdditional research is needed to learn if these differences have a genetic or an environ-mental basis An implication of these data is that the movement of tarpon within thewestern North Atlantic may be sufficiently localized for regional differences in life histo-ries to arise If so this emphasizes the need for conservation of tarpon habitat and wisemanagement of the fishery in both Florida and Costa Rica because movement of tarponinto these fisheries from other areas may be limited

ACKNOWLEDGMENTS

We thank the D Hawley Foundation the Pate Foundation Wildlife Conservation Internationaland the New York Zoological Society for their support Thanks also to Capt M Collins B Pateand A Carr III We also thank the anglers tournament participants and taxidermists who pro-vided the specimens examined in particular in Florida we thank I Shaw Taxidermy PfluegerTaxidermy the Boca Grande Fishing Guides Association the Florida Keys Fishing Guides Asso-ciation the Gold Cup Tarpon Tournament the Suncoast Tarpon Roundup and Millers Marina inCosta Rica we thank B Barnes of Casa Mar fishing lodge and T Staley of the Rio Colorado lodgeMany people participated in portions of this study including R Bishop L Crabtree F Cross andother employees of the Florida Game and Freshwater Fish Commission C Harnden D HarshanyV Lopez G Matute V Neugebauer D Snodgrass and C Stevens I Quintero-Hunter and HGrier provided advice on histology J Colvocoresses P Hood S Kennedy J Leiby R McBrideM Murphy K Peters J Quinn and K Sulak made helpful comments that improved the manu-script Thanks to the Wildlife Service of Costa Rica and the Barra del Colorado National Wildlife


Refuge for their cooperation This project was supported in part under funding from the Depart-ment of the Interior US Fish and Wildlife Service Federal Aid for Sportfish Restoration ProjectNumber F-59 the Florida Marine Fisheries Commission the Don Hawley Foundation and the PateFoundation Portions of these data were included in a dissertation submitted by E C Cyr as partialfulfillment of the requirements of the PhD degree University of South Carolina This paper iscontribution No 1055 of the Belle W Baruch Institute for Marine Biology and Coastal ResearchUniversity of South Carolina Columbia

LITERATURE CITED

Breder C M 1944 Materials for the study of the life history of Tarpon atlanticus Zoologica 29217-252

Chacoacuten Chaverri D and W O McLarney 1992 Desarrollo temprano del saacutebalo Megalopsatlanticus (Pisces Megalopidae) Rev Biol Trop 40 171-177

Crabtree R E 1995 Relationship between lunar phase and spawning activity of tarpon Megalopsatlanticus with notes on the distribution of larvae Bull Mar Sci 56895-899

____________ E C Cyr R E Bishop L M Falkenstein and J M Dean 1992 Age and growthof tarpon Megalops atlanticus larvae in the eastern Gulf of Mexico with notes on relativeabundance and probable spawning areas Environ Biol Fish 35 361-370

____________ E C Cyr and JM Dean 1995 Age and growth of tarpon Megalops atlanticusfrom South Florida waters Fish Bull US 93 619-628

de Menezes M F and M P Paiva 1966 Notes on the biology of tarpon Tarpon atlanticus(Cuvier and Valenciennes) from coastal waters of Ceara State Brazil Arq Estac Biol MarUniv Fed Ceara 6 83-98

Hildebrand S F 1963 Family Elopidae Pages 111-131 in H B Bigelow ed Fishes of thewestern North Atlantic Part 3 Sears Foundation for Marine Research Yale Univ New Ha-ven CT 630 p

Murphy M D and R G Taylor 1990 Reproduction growth and mortality of red drum Sciaenopsoccelatus in Florida waters Fish Bull US 88531-542

Quintero-Hunter I H Grier and M Muscato 1991 Enhancement of histological detail usingmetanil yellow as counterstain in periodic acid Schiff rsquos hematoxylin staining of glycol meth-acrylate tissue sections Biotech Histochem 66 169-172

Shenker J M R Crabtree and G Zarillo 1995 Recruitment of larval tarpon and other fishes intothe Indian River Lagoon Bull Mar Sci 57284

Smith D G1980 Early larvae of the tarpon Megalops atlantica Valenciennes (Pisces Elopidae)with notes on spawning in the Gulf of Mexico and the Yucatan Channel Bull Mar Sci 30136-141

Wade R A 1962 The biology of the tarpon Megalops atlanticus and the ox-eye Megalopscyprinoides with emphasis on larval development Bull Mar Sci 12 545-603

Zale A V and S G Merrifield 1989 Species profiles life histories and environmental require-ments of coastal fishes and invertebrates (South Florida) - ladyfish and tarpon US Fish WildlServ Biol Rep 82(11104) US Army Corps Eng TR EL-82-4 17 p

Zar J H 1984 Biostatistical analysis Prentice Hall Englewood Cliffs New Jersey 718 p

DATE ACCEPTED April 26 1995

ADDRESSES (R E C) Florida Marine Research Institute Department of Environmental Protection100 Eighth Avenue SE St Petersburg Florida 33701 (E C C) Office of Protected ResourcesNational Marine Fisheries Service 1335 East-West Highway Silver Spring Maryland 20910 (DC C) Asociacioacuten ANAI Apdo 170-2070 Sabanilla Montes del Oca San Joseacute Costa Rica (W OM) ANAI Inc 1176 Bryson City Road Franklin North Carolina 28734 (J M D) Institute ofPublic Affairs Univ of South Carolina Columbia South Carolina 29208


area is catch-and-release and anglers usually fish with professional guides employed bylocal fishing lodges

Little information is available on the reproductive biology of tarpon Chacoacuten Chaverriand McLarney (1992) documented the occurrence of larvae and juveniles during July-November in Costa Rican inshore waters No other information on reproduction or ageand growth exists for the area More is known about the biology of tarpon from otherareas Crabtree et al (1992) and Crabtree (1995) described the early life history of tarponfrom Florida waters and found that spawning is seasonal and occurs offshore during May-August Onshore transport of larvae is episodic and affected by environmental events(Shenker et al 1995) Breder (1944) examined gonads of tarpon from Florida waters butdid not adequately describe either temporal spawning patterns or age and length at matu-rity Crabtree et al (1995) described the age and growth of tarpon from Florida watersand found that tarpon are long-lived and can reach ages greater than 50 yrs De Menezesand Paiva (1966) examined gonads from tarpon caught off the northeast coast of Braziland found that reproduction occurs during October-January In this paper we describeseasonal spawning patterns length at sexual maturity and fecundity of tarpon from SouthFlorida and from the Rio Colorado area of Costa Rica Age estimates are presented fortarpon from Costa Rican waters

MATERIALS AND METHODS

We obtained Florida tarpon from a variety of sources from April 1988 to November 1993 Mostlarge fish (gt1100 mm FL) were obtained from taxidermists in Fort Myers and Fort Lauderdale andwere caught in either the Florida Keys or Boca Grande Pass on Floridarsquos Gulf coast (26deg 43 N 82deg16 W) A second source of large fish was tournaments held in the Keys Boca Grande Pass and theTampa Bay area (27deg 40 N 82deg 35 W) All large tarpon were caught with hook-and-line gearSmall Florida tarpon (lt1100 mm FL) were taken with cast nets hook-and-line gear electroshockertrammel nets and gill nets at various locations Tarpon in Costa Rica were caught with hook-and-line gear during normal fishing operations conducted by fishing lodges located in the Rio Coloradoarea on the Caribbean coast of northeastern Costa Rica from May 1989 to January 1994

Standard length (SL) fork length (FL) and total length (TL) were measured to the nearest milli-meter (mm) All lengths reported are fork lengths Large tarpon (gt1100 mm) were weighed to thenearest 05 kg and smaller tarpon were weighed to the nearest gram Otoliths (sagittae) wereremoved cleaned with bleach (525 sodium hypochlorite) and rinsed first in water and then in95 ethanol Otoliths were stored dry or in 95 ethanol until sectioned Sex gonad conditionand gonad weight in grams were recorded Gonad samples were removed from the fish and pre-served in 10 buffered Formalin they were then soaked in water for 1 h and stored in 70 ethanolLength-weight regressions were calculated by linear regression of log

10-transformed data and were

compared with a t-test (Zar 1984)Histological sections of gonads from 737 Florida tarpon and 202 Costa Rican tarpon were pre-

pared and assessed for reproductive state Initially gonad sections were taken from all tarponAfter examining histological sections from 168 Florida tarpon smaller than 400 mm we concludedthat we could not reliably sex small tarpon and subsequently processed sections only from fishlarger than 400 mm Gonad samples were processed histologically with a modification of theperiodic acid Schiff rsquos stain for glycol-methacrylate sections with Weigertrsquos iron-hematoxylin as anuclear stain and metanil yellow as a counterstain (Quintero-Hunter et al 1991) Gonads wereclassified based on the modified maturity criteria of Murphy and Taylor (1990) in Table 1 Thepresence of widespread atresia in inactive ovaries was interpreted as evidence of past reproductive





























ezis




ezis




10-



RESULTS































DISCUSSION












srorre

Xb+a=YY X n a

)ES1(b

)ES1(LF LS 512 794343 89001 2890

)135321( )39000(LF LT 412 560043 64980 1890

)298331( )58000(LS LF 512 33699 72790 2890

)23232 )09000(LS LT 312 712054 71780 0790

)797561( )50100(LT LS 312 926869 82111 0790

)315871( )53100(LT LF 412 143766 86901 1890

)833341( )40100(gol

01TW gol

01LF 611 31768- 47223 7680

)selamef( )73730( )28110(gol

01TW gol

01LF 29 95447- 96282 8580

)selam( )85730( )41210(gol

01LF gol

01TWO 69 16823 68330 1260

)80200( )14400(gol

01CEF gol

01TW 23 83825 93301 0550

)66920( )90710(







ACKNOWLEDGMENTS




LITERATURE CITED













































ezis




ezis




10-



RESULTS































DISCUSSION












srorre

Xb+a=YY X n a

)ES1(b

)ES1(LF LS 512 794343 89001 2890

)135321( )39000(LF LT 412 560043 64980 1890

)298331( )58000(LS LF 512 33699 72790 2890

)23232 )09000(LS LT 312 712054 71780 0790

)797561( )50100(LT LS 312 926869 82111 0790

)315871( )53100(LT LF 412 143766 86901 1890

)833341( )40100(gol

01TW gol

01LF 611 31768- 47223 7680

)selamef( )73730( )28110(gol

01TW gol

01LF 29 95447- 96282 8580

)selam( )85730( )41210(gol

01LF gol

01TWO 69 16823 68330 1260

)80200( )14400(gol

01CEF gol

01TW 23 83825 93301 0550

)66920( )90710(







ACKNOWLEDGMENTS




LITERATURE CITED




















10-



RESULTS































DISCUSSION












srorre

Xb+a=YY X n a

)ES1(b

)ES1(LF LS 512 794343 89001 2890

)135321( )39000(LF LT 412 560043 64980 1890

)298331( )58000(LS LF 512 33699 72790 2890

)23232 )09000(LS LT 312 712054 71780 0790

)797561( )50100(LT LS 312 926869 82111 0790

)315871( )53100(LT LF 412 143766 86901 1890

)833341( )40100(gol

01TW gol

01LF 611 31768- 47223 7680

)selamef( )73730( )28110(gol

01TW gol

01LF 29 95447- 96282 8580

)selam( )85730( )41210(gol

01LF gol

01TWO 69 16823 68330 1260

)80200( )14400(gol

01CEF gol

01TW 23 83825 93301 0550

)66920( )90710(







ACKNOWLEDGMENTS




LITERATURE CITED













































DISCUSSION












srorre

Xb+a=YY X n a

)ES1(b

)ES1(LF LS 512 794343 89001 2890

)135321( )39000(LF LT 412 560043 64980 1890

)298331( )58000(LS LF 512 33699 72790 2890

)23232 )09000(LS LT 312 712054 71780 0790

)797561( )50100(LT LS 312 926869 82111 0790

)315871( )53100(LT LF 412 143766 86901 1890

)833341( )40100(gol

01TW gol

01LF 611 31768- 47223 7680

)selamef( )73730( )28110(gol

01TW gol

01LF 29 95447- 96282 8580

)selam( )85730( )41210(gol

01LF gol

01TWO 69 16823 68330 1260

)80200( )14400(gol

01CEF gol

01TW 23 83825 93301 0550

)66920( )90710(







ACKNOWLEDGMENTS




LITERATURE CITED


























srorre

Xb+a=YY X n a

)ES1(b

)ES1(LF LS 512 794343 89001 2890

)135321( )39000(LF LT 412 560043 64980 1890

)298331( )58000(LS LF 512 33699 72790 2890

)23232 )09000(LS LT 312 712054 71780 0790

)797561( )50100(LT LS 312 926869 82111 0790

)315871( )53100(LT LF 412 143766 86901 1890

)833341( )40100(gol

01TW gol

01LF 611 31768- 47223 7680

)selamef( )73730( )28110(gol

01TW gol

01LF 29 95447- 96282 8580

)selam( )85730( )41210(gol

01LF gol

01TWO 69 16823 68330 1260

)80200( )14400(gol

01CEF gol

01TW 23 83825 93301 0550

)66920( )90710(







ACKNOWLEDGMENTS




LITERATURE CITED























ACKNOWLEDGMENTS




LITERATURE CITED



















LITERATURE CITED

















reproduction megalopsatlanticus

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