REFERENCE C O W Do Not Remove from the Library

U. S. Fish and Wildlife Service

Biological Report 82(11.1()4) National Wetlands Kescarcn .. :nrer 'TR EL-82.4 JUIY 1989 700 Cajun Dome Eoulc-tr.;yri

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

LADYFISH AND TARPON

Fish and Wildlife Service Coastal Ecology Group

Waterways Experiment Station

U.S. Department of the Interior U.S. Army Corps of Engineers

Bio log i ca l Report 82(11.104) TR EL-82-4 July 1989

Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements o f Coastal F i shes and Inver tebra tes (South F l o r i d a )

LADYFISH AND TARPON

Alexander V . Zale and

Susan G. M e r r i f i e l d

Oklahoma Cooperative Fish and W i l d l i f e Research U n i t Department o f Zoology

404 L i f e Sciences West Oklahoma S ta te U n i v e r s i t y

S t i l l water, OK 74078

P r o j e c t O f f i c e r David b r a n

Nat ional We tl ands Research Center U.S. F i sh and W i l d l i f e S r v i c e

1010 Gause Boulevard S l ide1 1, LA 70458

Performed f o r

Coastal Ecology Group Waterways Experiment S t a t i o n U.S. Army Corps o f Engineers

Vicksburg, MS 39180

and

Nat ional Wetlands Research Center Research and Development F i sh and Mi1 d l i f e Serv ice

U .S. Department o f t h e I n t e r i o r Washington, DC 20240

This se r i es may be referenced as fo l l ows :

U.S. F i sh and W i l d l i f e Service. 1983-19 . Species p r o f i l e s : l i f e h i s t o r i e s and environmental requirements o f c o a s m f i s h e s and inver tebra tes . U.S. F i sh Wi ld l . Serv. B i o l . Rep. 82(11). U.S. Army Corps o f Engineers, TR EL-82-4.

Th is p r o f i l e may be c i t e d as fo l lows:

Zale, A.V., and S.G. M e r r i f i e l d . 1989. Species p r o f i l e s : l i f e h i s t o r i e s and environmental requirements o f coas ta l f i s h e s and i nve r teb ra tes (South F l o r i d a ) -- l a d y f i s h and tarpon. U.S. F i s h Wi ld l . Serv. B i o l . Rep. 82(11.104). U.S. Army Corps o f Engineers, TR EL-82-4. 17 pp.

PREFACE

This species p r o f i l e i s one o f a ser ies on coastal aquat ic organisms, p r i n c i p a l l y f i s h , o f sport , commercial, o r eco log ica l importance. The p r o f i l e s are designed t o prov ide coastal managers, engineers, and b i o l o g i s t s w i t h a b r i e f comprehensive sketch o f t he b i o l o g i c a l c h a r a c t e r i s t i c s and environmental requirements o f t he species and t o descr ibe how populat ions o f t he species may be expected t o reac t t o environmental changes caused by coastal development. Each p r o f i l e has sect ions on taxonomy, 1 i f e h i s to ry , eco log ica l r o l e , environmental requirements, and economic importance, i f appl i cab le . A t h ree - r i ng b inder i s used f o r t h i s ser ies so t h a t new p r o f i l e s can be added as they are prepared. This p r o j e c t i s j o i n t l y planned and f inanced by the U. S. Army Corps o f Engineers and the U.S. F i sh and W i l d l i f e Service.

Suggestions o r questions regarding t h i s r e p o r t should be d i rec ted t o one of t he f o l l owing addresses.

In format ion Transfer S p e c i a l i s t Nat ional Wetlands Research Center U.S. F i sh and W i l d l i f e Service NASA-Sl i d e l 1 Computer Complex 1010 Gause Boulevard S l i d e l l , LA 70458

U. S. Army Engineer Waterways Experiment S t a t i o n At tent ion : WESER-C Post O f f i c e Box 631 Vicksburg, MS 39180

CONVERSION TABLE

M e t r i c t o U.S. Customary

m i l l i m e t e r s (mm) cent imeters (cm) meters (m) meters (m) k i l omete rs (km) k i l omete rs (km)

square meters (m2) 10.76 square k i lometers (km2) 0.3861 hectares (ha) 2.471

l i t e r s (1) cub ic meters (m3) cub ic meters (m3)

m i l l i g r a m s (mg) grams (g) k i 1 ograms (kg) m e t r i c tons (t) m e t r i c tons (t)

k i l o c a l o r i e s ( k c a l ) Ce ls ius degrees ( O C )

U.S. Customary t o M e t r i c

inches 25.40 inches 2.54 f e e t ( f t ) 0.3048 fathoms 1.829 s t a t u t e m i l e s (mi) 1.609 n a u t i c a l m i l e s (nmi) 1.852

square f e e t ( f t 2 ) square m i l e s (mi2) acres

g a l l o n s ( g a l ) cub ic f e e t ( f t 3 ) ac re - fee t

ounces (oz) ounces (02)

pounds ( l b ) pounds ( l b ) s h o r t tons ( t o n )

B r i t i s h thermal u n i t s (Btu) Fahrenhei t degrees (OF)

To Obta in

inches i nc hes f e e t fathoms s t a t u t e m i l e s n a u t i c a l m i l e s

square f e e t square m i l e s acres

ga l 1 ons cub ic f e e t a c r e - f e e t

ounces ounces pounds pounds s h o r t tons

B r i t i s h thermal u n i t s Fahrenhei t degrees

m i l l i m e t e r s cen t imete rs meters meters k i 1 ometers k i 1 ometers

square meters square k i 1 ometers hectares

1 i t e r s cubic meters cub ic meters

m i l l i g r a m s grams k i 1 ograms m e t r i c tons m e t r i c tons

k i l o c a l o r i e s Cel s i u s degrees

CONTENTS

Page PREFACE ................................................................... i j i CONVERSION TABLE .......................................................... l v ACKNOWLEDGMENTS ........................................................... v i

NOMENCLATURE/TAXONOMY/RANGE ................................................ 1 MORPHOLOGY AND IDENTIFICATION AIDS ........................................ 3

Lady f i sh ................................................................ 3 Tarpon .................................................................. 4

REASON FOR INCLUSION IN THIS SERIES ....................................... 4 LIFE HISTORIES ............................................................ 4 GROWTH CHARACTERISTICS .................................................... 7

Age and Growth .......................................................... 7 Morphometric Re la t i ons .................................................. 8

FISHERY ................................................................... 8 ECOLOGICAL ROLE ........................................................... 9

Feeding Behavior/Food Hab i t s ............................................ 9 Predators ............................................................... 10 Paras i tes ............................................................... 10

ENVIRONMENTAL REQUIREMENTS ................................................ 10 Temperature ............................................................. 10 S a l i n i t y ................................................................ 11 Disso lved Oxygen ........................................................ 11 Contaminants ............................................................ 12 T u r b i d i t y ............................................................... 12 Wetlands Dest ruc t ion and Degradation .................................... 12

LITERATURE CITED .......................................................... 13

ACKNOWLEDGMENTS

D r a f t s o f t h i s Species P r o f i l e were c r i t i c a l l y reviewed by Ed Rutherford, Nat ional Park Service, Everglades N a t i o n a l Park, F lo r i da ; C. R i c h a r d Robins, U n i v e r s i t y of Miami, Miami, F lo r i da ; and Paul H. Eschmeyer, E d i t o r i a l O f f i ce , U.S. F i sh and W i l d l i f e Service, F o r t Co l l i ns , Colorado. She i la G. Johnson, Edmon Low L i b r a r y , Oklahoma S t a t e U n i v e r s i t y , p r o v i d e d except ional assistance w i t h 1 i te ra tu re searches and i nter -1 i bra ry 1 oan. H. Frank1 i n Perc iva l o f the F l o r i d a Cooperative F i sh and W i l d l i f e Research Uni t , Un ive rs i t y o f F lo r i da , Gainesvi l l e , and 0. Eugene Maughan o f the Oklahoma Uni t provided admin i s t ra t i ve assistance.

Figure 1. A: l ady f i sh ; B: tarpon.

LADYFISH AND TARPON

S c i e n t i f i c name ......... Elops saurus Linnaeus (Robins e t a1 . TWOT -

Prefer red common name ....... 1 adyf i sh (F igure 1A)

Other common names . . bigeyed her r ing , b o n y - f i sh, c h i ro , Francesca, John M a r i g g l e , L i z a , m a t a j u e l o r e a l , p i o j o , skipjack, tenpounder (El dred and Lyons 1966; Jordan and Evermann 19691

C l ass ................... Osteichthyes Order .................... El opiformes Family ...................... El op i dae

Geographic range .... western A t l a n t i c Ocean from Bermuda and southern New England (but uncommon n o r t h o f Cape Hat teras) t o R io de Janeiro, B r a z i l , and t h r o u g h o u t t h e G u l f o f Mexico (F igure 2); a l so occurs i n t h e I n - d i a n and w e s t e r n P a c i f i c Oceans (Jordan and Evermann 1896; B i gelow and Schroeder 1953; B r i g g s 1958; Berra 1981). Mar ine and b r a c k i s h es tua r ine ( E l d r e d and Lyons 1966; Nel son 1984).

S c i e n t i f i c name . . Megalops a t1 ant icus Valenciennes (Rob-. 1980)

T. PETERSBURG

PALM BEACH

CAPE ROMAN

THOUSAND ISLANDS

MILES

KILOMETERS

FLORIDA

F i g u r e 2. L a d y f i s h and t a r p o n a r e d i s t r i b u t e d a l o n g t h e e n t i r e c o a s t o f Sou th F l o r i d a i n t h e C o n t i n e n t a l She l f and b r a c k i s h e s t u a r i n e w a t e r s ; t a r p o n a s c e n d r i v e r s i n t o f r e s h w a t e r a l s o .

P r e f e r r e d common name ......... tarpon ( F i g u r e 1B)

Other common names ........ b i g sca le , caffum, grande e c a i l l e y grande ecoy, j e w f i s h , s a b a l o , s a b i l o r e a l , sadina, s a v a l 1 e, s a v a l 1 o, s a v a l o- r e a l , savani 1 1 a, s i 1 v e r f i s h , s i 1 ve r k i n g , tarpom, t a rpum ( G i l l 1907; H i ldebrand 1937; Babcock 1951; Wade 1962a; Jordan and Evermann 1969)

Class ................... Oste ich thyes Order .................... Elop i fo rmes Fami ly ....... Elop idae o r Megalopidae

The t a r p o n was p l a c e d i n t h e E lop idae by Gos l ine (1971) and Robins e t a1 . (1980) , whereas Greenwood e t a l . (1966), Forey (1973a, 1973b1, and Nelson (1984) recogn ized t h e Megalopidae and Elopidae as separate f a m i l i e s w i t h i n t h e suborder E lopo ide i . The i s s u e i s equivocal and un l i k e l y t o be reso l ved soon.

.... Geographic range Western A t l a n t i c Ocean f r o m V i r g i n i a t o B r a z i l and G u l f o f Mex ico (F i gu re 2) ; e a s t e r n A t l a n t i c o f f t r o p i c a l A f r i c a ; c h i e f c e n t e r s o f abundance a r e t h e West I nd ies , F l o r i d a , and G u l f o f Mexico; s t r a g g l e r s r e c o r d e d f r o m N o v a Sco t i a , Bermuda, Argent ina, and the P a c i f i c te rminus o f t he Panama Canal (H i1 debrand 1939; Wade 1962a, 1969; Nelson 1984). No ev idence e x i s t s t o suggest t h a t ta rpon have become es- t a b l i s h e d i n t h e P a c i f i c (Swanson 1946; Wade 1962a). Genera l l y mar ine o r b rack i sh es tua r i ne , b u t o f t e n as- c e n d s r i v e r s i n t o f r e s h w a t e r 1951; Wade 1962a; Robins 1978; Nelson 1984).

MORPHOLOGY/IDENTIFICATION AIDS

'The l a d y f i s h and t a rpon a re bo th h e r r i ng-1 i ke i n general appearance b u t a r e r e a d i l y d i s t i n g u i s h e d f r o m c l u p e i d s by t h e presence o f an e l o n - g a t e bony g u l a r p l a t e between t h e b ranches o f t h e lower jaw and a much

l a r g e r mouth; t h e j a w e x t e n d s con- s i d e r a b l y p o s t e r i o r t o t h e r e a r edge o f t h e o r b i t ( B i g e l ow and Sch roede r 1 9 5 3 ) . The b e l l y i s n o t k e e l e d o r s e r r a t e d as i n he r r i ngs , b u t i s r e l a - ti v e l y broad and covered w i t h o r d i n a r y sca les (Jordan and Evermann 1969).

The f o l l o w i n g d e s c r i p t i o n o f t h e E l o p i dae ( i n c l u d i ng t h e t a r p o n i s summar ized f r o m J o r d a n and Evermann 1 1 9 6 9 ) . B o d y e l o n g a t e , somewhat compressed, and c o v e r e d w i t h s i l v e r y c y c l o i d s c a l e s . No s c a l e s on head. L a t e r a l l i n e p r e s e n t . Mouth b road , lower jaw prominen t . P r e m a x i l l a r i e s s h o r t and n o n p r o t a c t i l e ; max i1 l a r i e s form l a t e r a l marg ins o f t h e upper jaw. Eye r e 1 a t i v e l y 1 a rge , w i t h a d i p o s e e y e l i d . Bands o f v i l l i f o r m t e e t h on j aws , vomer, p a l a t i n e s , p t e r y g o i d s , tongue, and base o f s k u l l . Opercular bones t h i n, w i t h expanded membranous m a r g i n s . G i l l membranes e n t i r e l y s e p a r a t e and f r e e f r o m t h e i s t h m u s ; g i l l r a k e r s l o n g and s l e n d e r . D o r s a l f i n i n s e r t e d over o r s l i g h t l y b e h i n d t he p e l v i c s . Caudal f i n forked, dor- s a l and a n a l f i n s d e p r e s s i b l e i n t o s c a l y shea ths . No sp ines o r ad ipose f i n . Ve ry l o n g a c c e s s o r y s c a l e s a t t h e p e c t o r a l s and p e l v i c s .

L a d y f i sh

Body v e r y e l o n g a t e and c o v e r e d w i t h s m a l l , t h i n , s i l v e r y s c a l e s . Head s m a l l and p o i n t e d , w i t h v e r y 1 a r g e t e r m i n a l m o u t h ; m a x i 1 1 a r y r e a c h e s f a r b e h i n d eye . B r a n c h i o s - t e g a l r a y s 30. D o r s a l f i n i n s e r t e d s l i g h t l y beh ind t h e p e l v i c s . Dorsal , a n a l , and p e l v i c f i n r a y counts, 20, 13, and 15, r e s p e c t i v e l y . C a u d a l l obes l o n g and s lender . L a t e r a l l i n e s t r a i g h t , w i t h s i m p l e pores , 110 t o 120 s c a l e s . C o l o r s i l v e r y a1 1 o v e r and b l u i s h d o r s a l l y , w i t h l owe r p a r t s o f s i des and v e n t r a l su r f ace y e l l o w i s h o r w h i t e . D o r s a l a n d c a u d a l f i n s dusky ye1 1 owi sh and s i 1 very. Pel v i c s and pec to ra l s speckled, ye1 1 owi shy and

dusky. Reaches a maximum l e n g t h o f about 1 m ( u s u a l l y l e s s than 60 cm) and weight o f several k i l ograms. Data from Bigelow and Schroeder (1953) and Jordan and Evermann (1969).

Body o b l o n g , compressed , and cove red w i t h l a r g e , t h i c k , s i l v e r y , c y c l o i d scales. Mouth l a r g e and supe- r i or . Branchiostegal rays 23. Dorsal f i n w i t h 12 r a y s , i n s e r t e d c o n - s i d e r a b l y b e h i n d t h e p e l v i c s . Anal deep ly f a l c a t e , 20 rays, about tw ice as l ong as dorsal , has g r e a t l y e l o n - gated l a s t ray. Caudal w ide ly fo rked and s c a l y . L a t e r a l l i n e n e a r l y s t r a i g h t , 41 t o 48 scales; i t s tubes r a d i a t e w ide ly over the sur face o f the sca les . V e r t e b r a l c o u n t s 53 t o 57. Color b r i g h t s i 1 ver, w i t h dorsal sur- f ace somewhat da rke r than v e n t r a l . Reaches 2 t o 2.6 m and over 90 kg. D a t a f r o m B i g e l ow and S c h r o e d e r (19531, Jordan and Evermann (1969) , and Nelson (1984).

The two spec ies a r e e a s i l y d i s - t ingu ished (Jordan and Evermann 1969). The 1 a d y f i sh has 1 arge pseudobranchs and small scales. The 1 a s t ray o f the dorsal i s no t elongated, and the anal f i n i s small e r than the dorsal . Con- v e r s e l y , t h e t a r p o n has l a r g e sca les and no pseudobranchs. The l a s t r a y o f the dorsal i s elongated, i t s f r e e por- t i o n being as l ong as, o r longer than, the he igh t o f the f i n . The anal f i n i s l a r g e r than the dorsal .

REASON FOR INCLUSION IN THIS SERIES

The tarpon i s the premier inshore big-game f i s h o f t h e F l o r i d a c o a s t (McLane 1974; Robins 1978). Esteemed f o r i t s stamina, s t r e n g t h , and espe- c i a l l y i t s l e a p i n g p rowess , i t i s a v i d l y sought by a n g l e r s . Numerous a n n u a l t o u r n a m e n t s a r e d i r e c t e d s p e c i f i c a l l y a t t h i s species. T o u r i s t

revenues generated by the f i s h e r y are f o r m i d a b l e . The l a d y f i s h i s a l s o sought by anglers; i t has the s p o r t i n g a t t r i b u t e s o f the tarpon, b u t comes i n a smal ler package s u i t a b l e f o r l i g h t t a c k l e . Both spec ies are considered i n e d i b l e i n the Un i ted States because o f t h e b o n i n e s s o f t he f l e s h , and t h e r e f o r e do n o t s u p p o r t commercia l f i s h e r i e s . However, they are eaten i n 1 i m i t e d q u a n t i t i e s e l s e w h e r e (Hi1 debrand 1939; Babcock 1951).

LIFE HISTORIES

Spawning 1 o c a t i o n s o f l a d y f i sh are unknown, b u t have been i n f e r r e d t o be o f f s h o r e t h r o u g h o u t most o f t h e range o f the species, as judged by the l o c a t i o n s o f c a p t u r e o f e a r l y l a r v a e ( H i l d e b r a n d 1943; Gehr i n g e r 1959a; E l d r e d and Lyons 1966) . S i m i l a r l y , t a r p o n a r e b e l i e v e d t o s p a w n throughout most o f t h e i r range i n o f f - shore waters (Wade 1962a; H i 1 debrand 1963; Eldred 1967). Eldred (1967, 1968, 1972) i n f e r r e d from l a r v a l capture l oca t i ons t h a t spawning took p lace i n the F l o r i d a S t r a i t s , Gulf Stream, and Caribbean . Smith (1980) prov ided st rong evidence (based on t h e c o l l e c t i o n o f very young l a rvae ) t h a t tarpon spawn o f f the Caribbean coast o f Mexico near Cozumel and Banco Chinchorro (Yucatan Channel ) , o f f west-centra l F lo r ida , and o f f the southern p a r t o f Veracruz, Mexico. The presence o f small l a r vae o f f Georgia (Gehringer 1959b) and North Carol ina (Ber r ien e t a l . 1978) i ndi ca tes t h a t spawn i ng occurs there a lso, and probably t o some ex ten t a long the e n t i r e coast from F l o r i d a t o Cape Hat teras.

F e c u n d i t y o f a t a r p o n 2 m l o n g was e s t i m a t e d t o be about 12,200,000 (Babcock 1951) . Sexual m a t u r i t y i s a t t a i n e d a t a t o t a l l e n g t h (TL) o f about 120 cm (Breder 1944). Fecundi ty a n d s i z e a t s e x u a l m a t u r i t y o f 1 adyf i sh are unknown.

Eggs o f n e i t h e r t a r p o n n o r l a d y f i s h have been described, nor are yo'l k-sac 1 arvae o f the 1 adyf i sh known. Smith (1980) described and ill u s t r a t e d l a t e yo1 k-sac l a r v a e o f t a rpon . H i s smal les t specimen, 5.7 mm i n notochord l e n g t h (NL), r e t a i n e d on ly t r a c e amounts o f yo l k , i n d i c a t i n g t h a t t he yolk-sac stage ends a t about 6 mm NL. Eggs and yo1 k-sac 1 arvae t h a t Breder (1944) be l ieved t o be tarpon were e r - roneously i d e n t i f i e d (E l dred 1972).

Post yo1 k-sac 1 arva l deve l opment i n bo th spec ies p rog resses t h r o u g h t h r e e d i s t i n c t s tages ( t e r m i no1 ogy from Wade 1962a, mod i f i ed by Jones e t a l . 1978). Stage I i s an i n i t i a l p e r i o d o f l e n g t h i n c r e a s e t h a t c u l - minates i n the development o f a f u l l y formed 1 eptocephal us 1 arva. The 1 ep- tocephal us i s charac ter ized by a 1 ong, r i bbon-1 i k e , c o l o r l e s s , t r a n s p a r e n t body; l a r g e fang-1 i k e t e e t h ; a v e r y small head; and small f i n s . It l a c k s g i l l s and red blood c e l l s , and i t s gu t i s no t open (Robins 1978). Oxygen and n u t r i e n t s a re absorbed th rough t h e s k i n . I n S t a g e 11, t h e l a r v a d e c r e a s e s m a r k e d l y i n l e n g t h and gradua l ly loses the r i bbon-1 i k e l e p - tocepha l ic morphology. Stage I 1 1 i s a second pe r iod o f l eng th increase t h a t terminates w i t h t h e b e g i n n i n g o f t h e j u v e n i l e stage. La te i n Stage I 1 and t h r o u g h o u t Stage I 1 1 t h e l a r v a un- dergoes pronounced changes i n body form, i n c l u d i n g i n c r e a s e s i n body depth, snout 1 ength, head length, dor- sal and anal f i n he igh t , and pec tora l f i n size. La te i n Stage 111, the body s t a r t s t o become opaque and s i l v e r y . Juven i les resemble a d u l t s i n gene ra l appearance. E a r l y l i f e h i s t o r y stages o f tarpon were descr ibed by Hi ldebrand (1934), H o l l i s t e r (1939) , H a r r i ng ton ( 1 9 5 8 ) , G e h r i n g e r ( 1 9 5 9 b 1 , Wade (1962a1, E l d r e d (1967, 1968, 19721, Mercado and C i a r d e l l i (19721, Jones e t a l . ( 1 9 7 8 1 , and S m i t h ( 1 9 8 0 ) . D e s c r i p t i o n s o f 1 a r v a l and j u v e n i l e l a d y f i s h were publ ished by H i l d e b r a n d (19431, A l i kunh i and Rao (19511, Geh- r i n g e r ( 1 9 5 9 a 1 , E l d r e d and Lyons (1966), and Jones e t a1 . (1978).

Ladyf ish grow t o a maximum stand- a r d l e n g t h ( S L ) o f abou t 40-45 mm du r ing Stage I, shr ink t o about 18-20 mm SL d u r i n g Stage 11, and metamor- phose i n t o j uven i l es a t about 30-35 mm SL a t the end o f Stage I 1 1 (Hi ldebrand 1943; A l ikunh i and Rao 1951; Gehringer 1959a; Jones e t a1 . 1978). Durat ions o f about 29 days f o r Stage I 1 and 42 days f o r Stage I 1 1 were r e p o r t e d by Gehringer (1959a) f o r l a r vae reared i n t h e 1 a b o r a t o r y . A l i k u n h i and Rao (1951) repor ted the dura t ion o f Stages I 1 and I 1 1 combined as on l y 9 days i n t h e 1 abora to ry ; concurrent f i e l d c o l - 1 e c t i ons prov ided suppor t ing evidence f o r t h i s r a p i d r a t e o f change. No r e c o r d s o f w a t e r t empera tu re accom- panied the data f o r e i t h e r study.

S i z e s o f S tage I t a r p o n range from 6 mm NL t o 28 mm SL (Mercado and C i a r d e l l i 1972; Smith 1980). Dura t ion o f Stage I i s est imated t o be 2 t o 3 m o n t h s i n t h e ocean ( S m i t h 1980) . Larval tarpon shr ink t o about 14 mm SL d u r i n g Stage I 1 and become j u v e n i l e s a t a b o u t 40 mm SL a f t e r Stage I 1 1 (Wade 1962a) . D u r a t i o n of Stage I 1 was 20 -25 d a y s i n t h e l a b o r a t o r y (Mercado and C i a r d e l l i 1972). On the bas is o f Ha r r i ng ton ' s (1966) data, we e s t i m a t e d u r a t i o n o f Stage I 1 1 t o be about 7-8 weeks .

Spawni ng o f 1 a d y f i sh appears t o e x t e n d t h r o u g h o u t mos t o f t h e y e a r , perhaps peaking i n f a l l , as judged by t h e o c c u r r e n c e o f Stage I l a r v a e . A l i kunh i and Rao (1951) c o l l e c t e d l a t e Stage I 1 arvae from October t o Decem- b e r i n c o a s t a l I n d i a n wa te rs . H i l - d e b r a n d ( 1 9 4 3 ) c o l l e c t e d S t a g e I 1 arvae o f f Beaufort, North Carol i na, from October through May; o f f Texas i n February, March, A p r i l , and November; o f f the F l o r i d a Keys i n November; and o f f Cuba i n May. Offshore c o l l e c t i o n s o f Stage I l a r v a e were made by Geh- r i n g e r (1959a) o f f F l o r i d a and Georgia i n October, o f f South Caro l ina i n May, and o f f N o r t h C a r o l i n a i n November. A r n o l d e t a l . (1960) c o l l e c t e d l e p -

tocepha l i f rom e a r l y March t o mid-May near Gal veston, Texas. Tabb and Man- n ing (1961) repo r ted t h a t l a r v a e were abundant i n F l o r i d a Bay from September t h r o u g h December. E l d red and Lyons (1966 ) r e p o r t e d c o l l e c t i ng Stage I l e p t o c e p h a l i o f f F l o r i d a i n January, February, May, June, August, October, and December.

Summarizing va r i ous references on t h e occurrences o f l a r v a l tarpon, Robins (1978) and Smith (1980) noted t h a t Stage I l a r v a e occur from mid-May t o l a t e August , and Stage I 1 l a r v a e from l a t e June t o e a r l y October; they i n f e r r e d t h a t spawning occurs i n l a t e s p r i n g o r e a r l y summer.

Ear ly Stage 1 l a r vae o f l a d y f i s h were captured o f f s h o r e (Gehr inger 1959a) a t 28.5 p p t and 28.1 "C (E ld red and Lyons 1966). La te Stage I la rvae o c c u r i n s h o r e ( G e h r i nger 1959a) a t 26.3-38.5 p p t and 17.5-29.0 "C (E ld red and Lyons 1966) . 01 der e a r l y - l i f e s tages (S tage I 1 and I 1 1 l a r v a e and j u v e n i l e s ) i n h a b i t c o a s t a l beaches, canal s, bayous, 1 agoons, t i d a l ponds, c reeks , r i v e r s , and mosquito c o n t r o l impoundments (Erdman 1960; Z i 1 berberg 1966; Dahl b e r g 1972; Govoni and Mer- r i n e r 1978; G i l m o r e e t a l . 1981; Thompson and Deegan 1982; Sne l son 1983). They l i v e i n water o f a wide range of sa l i n i t i e s and temperatures : 14-45 p p t and 24-32 " C ( H a r r i n g t o n 1958); 17.5-39.0 p p t (Har r ing ton and H a r r i n g t o n 1961); 34.3-34.6 p p t and 18-23 O C (E ld red and Lyons 1966); 1.4- 11.2 p p t and 21-30 " C (Herke 1969) ; 0.1-28.7 p p t and >19.9 " C ( D a h l b e r g 1972); 10-20 p p t and <35 "C (Rose e t a l . 1975); 5.6-5.8 p p t ( T h e i l i n g and Loyacano 1976); 2.2-6.1 p p t (Govoni and M e r r i n e r 1978); 0.0-8.8 p p t and 16-28 "C (Thompson and Deegan 1982). Rose e t a1 . (1975) repo r ted a pH range o f 6.8-8.7 f o r a c o a s t a l impoundment i n h a b i t e d by j u v e n i l e l a d y f i s h . A d u l t l a d y f i s h u s u a l l y l i v e i n r e l a t i v e l y open i n s h o r e and c o a s t a l h a b i t a t s (Dahl berg 1972; G i l m o r e e t a1 . 1981;

Sne l son 1983) b u t may ascend r i v e r s f o r c o n s i d e r a b l e d i s t a n c e s ( T a g a t z 1967 1.

Hab i ta t s o f Stage I tarpon l a r v a e a r e c l e a r , warm, o c e a n i c w a t e r s (Gehringer 1959b; Robins 1978) w i t h i n 100 m o f t h e s u r f a c e (Wade 1962a) . Surface water temperatures a t c o l 1 ec- t i o n s i t e s ranged f rom 26.0 t o 30.0 "C and s a l i n i t i e s f rom 33.6 t o 36.0 p p t (Wade 1962a; B e r r i e n e t a l . 1 9 7 8 ; Smi th 1980 ) . E s t i m a t e d t e m p e r a t u r e and s a l i n i t y ranges a t d e p t h o f cap- t u r e were 22.2-28.4 " C and 33.6-36.7 p p t (Wade 1962a 1.

Stage I 1 and I 1 1 t a r p o n l a r v a e and j u v e n i l e s l i v e i n s a l t marsh and mangrove ponds, t i d a l creeks, r i v e r s , d i tches, beaches, and mosqui to-con t r o l impoundments ( S t o r e y and P e r r y 1933; Breder 1944; Simpson 1954; M o f f e t t and Randal 1 1957; Erdman 1960; H a r r i n g t o n and H a r r i ngton 1960, 1961; Wade 1962a, 1969; R i c k a r d s 1968; D a h l b e r g 1972; Tagatz 1973; G i l m o r e e t a l . 1981 ; Sne l son 1983 ) . These h a b i t a t s a r e t y p i c a l l y shal low ( < I m), have a sandy mud o r mud s u b s t r a t e w i t h no r o o t e d submerged v e g e t a t i o n , a r e 1 i ned by reeds o r mangroves, u s u a l l y have t u r - b i d o r dark-sta ined waters, and may be e i t h e r s tagnant o r have c o n s i d e r a b l e c u r r e n t (Beebe 1927 ; B r e d e r 1 9 3 3 ; Simpson 1954; Wade 1962a, 1969; Rick- ards 1968). I n such hab i t a t s , l a r v a e and j u v e n i l e s a r e a b l e t o w i t h s t a n d environmental c o n d i t i o n s d e l e t e r i o u s t o many o the r f i shes . Juven i l e ta rpon have been c o l l e c t e d a t w ide l y va ry ing s a l i n i t i e s : 31.8 p p t (Simpson 19541, 18.8-33.4 p p t ( M o f f e t t and R a n d a l l 1957) , 14-45 p p t ( H a r r i n g t o n 19581, 17.5-39.0 p p t ( H a r r i n g t o n and Har - r i n g t o n 19611, 0.0-22.3 p p t ( R i c k a r d s 19681, 0-47 p p t (Wade 19691, and 15-21 p p t (Gi lmore e t a1 . 1982). Most l a r - va l and j u v e n i l e tarpon l i v e a t r e l a - t i v e l y h i g h t e m p e r a t u r e s : 36.6 " C ( M o f f e t t and Randa l l 19571, 36.0 " C ( R i c k a r d s 19681, and 40 " C (Wade 1 9 6 9 ) . B e c a u s e t a r p o n r e s p i r e

a e r i a l l y (by g u l p i n g a i r ) a t l e a s t as e a r l y as t h e b e g i n n i n g o f Stage I 1 1 ( H a r r i n g t o n 1 9 6 6 1, 1 ow d i s s o l v e d o x y g e n c o n c e n t r a t i o n s a r e n o t d e l e t e r i o u s t o s u r v i v a l . The s t r o n g odor o f hyd rogen s u l f i d e a t c a p t u r e s i t e s , i n d i c a t i v e o f poor t i d a l f l u s h - ing , has been r e p o r t e d by v a r i o u s i n - v e s t i g a t o r s (e.g., Beebe 1927; Breder 1933, 1944; Rickards 1968; Wade 1969). J u v e n i l e t a r p o n a re o f t e n c o l l e c t e d f r o m i s o l a t e d marsh ponds t h a t a r e c o n n e c t e d t o t h e e s t u a r y o n l y d u r i n g s p r i n g t i d e s . Wade (1969) c o l l e c t e d j u v e n i l e ta rpon a t pH's o f 6.8 t o 8.2.

I n e a s t e r n F l o r i d a marshes, Wade ( 1 9 6 9 ) f o u n d S t a g e I 1 1 l a r v a e i n d i t c h e s a t t h e headwa te rs o f s m a l l creeks. Small j u v e n i l e s (40-80 mm SL) l i v e d i n l a r g e r d i t c h e s and c r e e k s , e s p e c i a l l y i n t h e deeper pools . Large j u v e n i l e s were found i n 1 a rger cana l s and r i v e r s . J u v e n i l e t a rpon eventu- a l l y emigra te f rom marsh and mangrove h a b i t a t s and e n t e r coas ta l wa te rs when they reach about 600-800 mm TL (Robins 1978). I n Georgia, t a rpon a re unable t o o v e r w i n t e r i n m a r s h h a b i t a t s ; j u v e n i 1 es l e f t marshes, presumably t o m i g r a t e sou th , by 1 a t e October, when t h e y had a t t a i n e d a b o u t 160 mm SL (R ickards 1968). A d u l t s l i v e i n bays, 1 agoons, and coas ta l h a b i t a t s (Breder 1944; Dahl b e r g 1972; G i l m o r e e t a1 . 1981; Snelson 1983) o r may c r u i s e t he open ocean (Robins 1978).

GROWTH CHARACTER1 ST1 CS

Age and Growth

M o f f e t t and R a n d a l l (19571, who examined l e n g t h - f r e q u e n c y d i s t r i bu- t i o n s o f j u v e n i l e ta rpon f rom a south F l o r i d a mangrove pond, r e p o r t e d t h a t modal l e n g t h s inc reased f rom 75-80 mm FL i n e a r l y September t o 110-115 mm FL a t t he end o f t h e month, and i n f e r r e d a l e n g t h i nc rease o f about 1.4 mm/day; r a t e s d e c l i n e d b y a b o u t 50% i n Oc- t o b e r . F i v e marked j u v e n i l e t a r p o n (301-376 mm FL when tagged) i n a south

F l o r i d a dra inage d i t c h grew an average o f 1.0 mm/day (range, 0.7-1.4 mm/day) f rom 22 August t o 20 October ( M o f f e t t and R a n d a l l 1 9 5 7 ) . O v e r t h e same p e r i o d , modal l e n g t h s o f t a r p o n i n t h i s p o p u l a t i o n i n c r e a s e d b y 1 .4 mm/day. I n a G e o r g i a s a l t m a r s h , j u v e n i l e t a r p o n g r e w a t a r a t e o f about 30 mm/month (R ickards 1968).

B r e d e r ( 1 9 4 4 ) , who de t e r m i n e d growth r a t e s o f c a p t i v e j u v e n i l e t a r - pon, wrote t h a t 12 f i s h ma in ta ined a t t h e o l d New York Aquar ium f o r 113 t o 314 days grew an a v e r a g e o f 0 . 0 8 8 mm/day ( r ange , 0.048-0.186 mm/day); i n i t i a l and f i n a l l e n g t h r a n g e s were 94-145 a n d 1 1 0 - 1 7 6 mm TL. T h r e e tagged f i s h (355-365 mm TL) c o n f i n e d i n n a t u r a l ponds i n s o u t h e r n F l o r i d a d i d n o t g r o w i n 1 3 3 t o 1 5 2 d a y s ( A u g u s t t o J a n u a r y ) . Two o t h e r s ( tagged i n J u l y ) grew f rom 345 t o 390 and f rom 370 t o 380 mm TL i n 258 and 167 days, r e s p e c t i v e l y . Four j u v e n i l e t a r p o n ( o r i g i n a l l y 2 3 0 - 3 5 0 mm T L ) ma in ta ined i n l a b o r a t o r y poo ls grew 13 t o 179 mm (mean i n c r e m e n t , 97 mm) i n 15 months; a f i f t h grew f r o m 436 t o 465 mm TL i n 6 months.

Ten ta rpon r a i s e d b y H a r r i n g t o n ( 1 9 6 6 ) i n t h e l a b o r a t o r y f r o m S tage I 1 1 l a r v a e (18.1-22.7 mm SL; mean, 21.4 mm) f o r 1 yea r grew t o 55.4-105.3 mm SL (mean, 67.2 mm SL).

A1 though s c a l e s o f a d u l t t a r p o n have d i s t i n c t r i n g s resembl i n g annul i ( B r e d e r 1944; M o f f e t t a n d R a n d a l l 19571, t h e s e m a r k s have n o t been v a l i d a t e d as annu l i and should be con- s i d e r e d w i t h e x t r e m e cau t i on . Back- c a l c u l a t e d mean l e n g t h s a t t h e forma- t i o n o f t h e s e p u t a t i v e a n n u l i a r e shown i n F i g u r e 3. Maximum age based on these checks was 16 yea rs ( M o f f e t t and Randal 1 1957 ) ; however, 1 a r g e r f i sh have been captured.

Gehringer (1959a rea red 1 a d y f i s h i n t he l a b o r a t o r y from e a r l y Stage I 1

t o t h e j u v e n i l e phase . R a t e s o f change i n standard l e n g t h d u r i n g the f i r s t p a r t o f Stage I 1 ( f rom about 35- 40 mn t o 25 mm SL) averaged -1.061 mm/day . F u r t h e r s h r i n k i ng t o a b o u t 20-21 mm SL proceeded a t about -0.342 mm/day. I n i t i a l l e n g t h i n c r e a s e du r ing e a r l y Stage 111, from about 20 t o 25 mn SL, averaged 0.140 mn/day. Growth r a t e s o f l a t e Stage I 1 1 l a rvae and e a r l y j u v e n i l e s ( ~ 6 0 mm SL) were about 0.626 mm/day. Larger j u v e n i l e s g r e w an a v e r a g e o f 0 .628 mm/day. F i e l d c o l l e c t i o n s suggested a f a s t e r r a t e o f growth (about 2 mn/day) under n a t u r a l c o n d i t i o n s (Gehringer 1959a). No i n fo rma t ion i s a v a i l a b l e on growth o f a d u l t 1 a d y f i sh.

Mor~homet r ic Re1 a t i ons

B rede r (1944) presented the f o l - 1 o w i n g 1 e n g t h - w e i g h t r e l a t i o n f o r a d u l t tarpon i n F l o r i d a :

where W = weight i n grams and TL = to - t a l l e n g t h i n m i l l ime te rs .

H a r r i n g t o n (1958 ) d e r i v e d t h e f o l l o w i n g l eng th -we i g h t r e l a t i o n f o r 154 tarpon, 16.0-45.5 mm SL:

where W = w e i g h t i n grams and SL = standard l eng th i n m i l l i m e t e r s . The r e l a t i o n i s v a l i d on l y f o r f i s h w i t h i n the s ta ted s i ze range.

On the bas is o f a graph presented by M o f f e t t and Randa l l (19571, we der ived the f o l 1 owing r e l a t i on between t o t a l length (TL) and f o r k l eng th (FL) f o r tarpon:

TI- = 1.10 FL.

Har r ing ton (1958 1 deve loped t h e f o l l o w i n g c o n v e r s i o n s be tween f o r k l e n g t h (FL ) , t o t a l l e n g t h (TL ) , and s t a n d a r d 1 e n g t h (SL i n m i 11 i m e t e r s f o r tarpon 25-54 mn SL:

Sekavec (1974) d e r i v e d the f o l - 1 owing length-we ight formula from 295 j u v e n i l e l a d y f i sh 45-201 mn FL f r o m Louisiana:

n m e t e o r t (Moffon md k n d a l 1957)

o out m r r t (Monen mna Rmndmll 1857)

0 10 15

NUMBER OF PUTATIVE ANNULI

F i g u r e 3. B a c k - c a l c u l a t e d mean l e n g t h s o f t a r p o n f r o m t h e west and e a s t c o a s t s o f F l o r i d a , a t p u t a t i v e annu l i on scales.

where W = w e i g h t i n grams and FL = fork l eng th i n m i l l i m e t e r s . Mean con- d i t i o n f a c t o r (K, where K = [W/(FL)'] x 106; Lag ler 1956) o f these f i s h was 8.1 (range 6.6-8.9).

FISHERY

The tarpon and l a d y f i s h f i s h e r i e s are s o l e l y rec rea t i ona l ; no commercial f i s h e r y e x i s t s f o r e i t h e r species i n the Un i ted States. Ne i the r species i s r e c o r d e d i n t h e N a t i o n a l M a r i n e R e c r e a t i o n a l F i s h e r i e s Survey and

r e g i o n a l c a t c h da ta a re n o n e x i s t e n t ( G r a n t L. Beardsley, Senior S c i e n t i s t f o r R e c r e a t i o n a l F i s h e r i e s , Nat iona l M a r i ne F i s h e r i es S e r v i c e , Sou theas t F i s h e r i e s C e n t e r , Miami, F l o r i d a ; pers. comm. 1.

T i1 mont e t a1 . (unpubl i shed) sum- m a r i z e d r e c r e a t i o n a l f i s h e r y s t a t i s - t i c s f o r t a r p o n and l a d y f i sh i n E v e r g l ades N a t i o n a l Park, F l o r i d a , f r om 1958 t h r o u g h 1984. Tarpon were sought by l e s s than 3% o f anglers and made up an ave rage o f 0.2% o f t h e r e p o r t e d r e c r e a t i o n a l ca tch annual l y . Mean annual c a t c h r a t e s v a r i e d f r o m 0.1 t o 0.4 f i sh /h . Less than 10% o f t h e t a r p o n c a u g h t were ha rves ted , p r i m a r i l y f o r t r o p h y mounts. Tarpon accounted f o r 1% o f the catch, 0.4% o f t h e h a r v e s t , and 7% o f the e f f o r t i n t he p r o f e s s i o n a l l y guided f i s h e r y i n the pa rk . Repor ted catch r a t e s sug- ges ted t h a t s t o c k s o f t a r p o n i n t h e park were re1 a t i v e l y stable.

Ladyf ish were commonly caught b u t i n f r e q u e n t l y ha rves ted by a n g l e r s i n Everg lades N a t i o n a l Park (T i lmont e t a l . , unpubl ished). L a d y f i s h made up abou t 5% o f t h e t o t a l repor ted ca tch b u t l e s s than 0.4% o f t h e h a r v e s t . Few a n g l e r s (0.02%) c o n s i d e r e d t h e f i s h a p re fe r red species. Mean annual ca tch r a t e s v a r i e d f r o m 0.25 t o 0.67 f i s h / h . L a d y f i s h p o p u l a t i o n abun- dances i n t he park were c y c l i c , peak- i n g about every f i v e years. However, a general increase i n l a d y f i s h abun- dances i n the park o c c u r r e d f r o m t h e l a t e 1960's through the e a r l y 1980's.

ECOLOGICAL ROLE

Feeding Behavi or/Food Hab i ts

S t a g e I t a r p o n a n d 1 a d y f i s h l a r v a e do n o t f o r a g e ; n u t r i e n t s a r e obta ined d i r e c t l y from seawater by i n - tegumentary absorpt ion ( P f e i l e r 1986).

Stage I 1 and I 1 1 t a r p o n l a r v a e and small j u v e n i l e s (< I25 mn SL) feed p r i m a r i l y on z o o p l a n k t o n ( e . g . ,

copepods and os t r a c o d s ) and secon- d a r i l y on i n s e c t s and sma l l f i s h e s ; l a r g e r j u v e n i l e s c o n t i n u e t o f e e d on z o o p l a n k t o n , b u t p r o g r e s s i v e l y i n - crease consumption o f i n s e c t s , f i s h e s ( e s p e c i a l l y p o e c i l i i d s a n d c y p r i n o d o n t i d s ) , c r a b s , and g r a s s sh r imps o f t h e genus P a l a e m o n e t e s (Beebe 1927; Breder 1933; M o t t e t t and Randa l l 1957; H a r r i n g t o n a n d H a r - r i n g t o n 1960, 1961; R i c k a r d s 1968) . Juven i l e tarpon are t y p i c a l l y c repus - c u l a r and noc turna l f o r a g e r s (Robi ns 1978).

I n l a b o r a t o r y s e t t i n g s , e a r l y Stage I 1 l a d y f i s h l a r v a e a t e 1 i v e p lankton ( A l i k u n h i and Rao 1951) and 1 i v e b r i n e sh r imp ( A r t e m i a ) naup l ii (Gehringer 1959a). S tage I 1 1 l a r v a e a te small l i v e Fundulus and Gambusia and pieces o f shrimp and f i s h . Under n a t u r a l c o n d i t i o n s , Stage I 1 and I 1 1 l a d y f i s h l a rvae (<50 mm SL) f e e d a l - most e x c l u s i v e l y on zooplankton; con- sumption o f zoop lank ton by j u v e n i l e s i s progress ive ly reduced as i nges t i on o f small f i s h e s and shrimps increases (Har r i ngton and H a r r i ngton 1961). Ladyf ish < lo0 mm long feed e s p e c i a l l y on insects, copepods, and o the r arthropods (Fyfe 1986).

A d u l t t a r p o n and l a d y f i s h a r e s t r i c t l y c a r n i v o r o u s a n d f e e d p r i m a r i l y on mi d -water p rey ( H i 1 de- b rand 1963; Sekavec 1974). Food i s swal 1 owed who1 e (Sekavec 1971).

A d u l t l a d y f i s h feed p r i m a r i l y on f i sh ; f i s h c o n s t i t u t e d 94%, 82%, and 34% of food i t e m s found i n l a d y f i s h stomachs by Sekavec (19741, Darne l1 (19581, and Knapp (19491, r e s p e c - t i v e l y . I n Sekavec 's (1974) s tudy , j u v e n i l e Gul f menhaden ( B r e v o o r t i a t y r a n n u s ) composed 72% o t t h e i d e n - t i f i a b l e f i s h consumed.

Decapod crustaceans a r e a l s o im- p o r t a n t foods o f l a d y f i s h . L i n t o n (1904 ) r e p o r t e d t h a t d i e t s o f 12 1 ady f i sh from North Caro l ina cons is ted exc l u s i v e l y o f shr imp. Knapp ( 1949) found t h a t 78.2% o f stomach c o n t e n t s

o f l a d y f i s h from the Texas coas t were r e p o r t e d f r o m t h e i n t e s t i n e o f c r u s t a c e a n s . Decapods made up 5.5% l a d y f i s h (Corkum 1959). (Sekavec 1974) and 10% (Darne l l 1958) o f t h e d i e t s o f l a d y f i s h f r o m Louis iana. ENVIRONMENTAL REQUIREMENTS

A d u l t t a r p o n f e e d b o t h n o c t u r - n a l l y and d i u r n a l l y (Wade 1962a) on a v a r i e t y o f organisms i n c l u d i n g mu1 l e t s ( M u g i l s p p . ) , p i n f i s h ( L a g o d o n r w d e s ) , a r i i d ca t f i shes , At1 a n t i c need1 e f i sh (St rongy l u ra mar ina) , sar- d i n e s (Harengu l a spp. ) , s h r i m p , and crabs (Babcock 1951; Wade 1962a).

Predators

P r e d a t i o n by c a r n i v o r o u s z o o p l a n k t e r s and sma l l f i s h e s un- doubtedly causes h igh m o r t a l i t y o f eggs and 1 arvae o f both l a d y f i s h and ta rpon be fore the l a r v a e en te r coas ta l nurs- e r y marshes. I n marshes, j u v e n i l e tarpon are probably immune t o p i s c i n e predat ion o ther than t h a t by j u v e n i l e l a d y f i s h o r t a r p o n (Beebe 1927; Mof- f e t t and Randall 1957; Rickards 1968; Wade 1969). Both species are probably p r e y e d u p o n b y p i s c i v o r o u s b i r d s (Beebe 1927; Rickards 19681, and a d u l t t a r p o n a r e o c c a s i o n a l l y e a t e n by s h a r k s , p o r p o i s e s , and a l l i g a t o r s (Wade 1962a, 1962b).

Pa ras i t es

T h e d i g e n e t i c t r e m a t o d e L e c i t h o c h i r i u m microstomum occurs i n t h e stomach o f t a r p o n (Manter 1947). The i sopods N e r o c i 1 a acumi n a t a and C y m o t h o a o e s t r u m a r e e x t e r n a l pa ras i t es (Babcock 1951; Pearse 1952). Causey (1953 ) r e p o r t e d t h e cope pod Para1 e b i on p e a r s e i from tarpon. The t r e m a t o d e B i v e s c u l a t a r p o n i s i s p r e s e n t i n t h e p y l o r i c caecae and a long the e n t i r e l e n g t h o f t he i n t e s - t i ne ( Sogandares-Berna l and H u t t o n 1959). Though n o t p a r a s i t i c , remoras ( Remora remora) are commonly observed a t t a c h e - a r g e t a r p o n (Babcock 1951; Wade 1962a).

T r e m a t o d e s o f t h e g e n e r a Bucephal us and Prosorhynchus have been

The tarpon and l a d y f i s h are d i s - ti n c t l y t h e r m o p h i l i c f i s h e s . Bo th have been r e p o r t e d i n c o l d - re1 a t e d f i s h k i l l s i n F l o r i d a ( S t o r e y and Gudger 1936; Storey 1937; Snelson and B r a d l e y 1 9 7 8 ) . A t P o r t A r a n s a s , Texas, annual t a r p o n abundances a r e c o r r e l a t e d w i t h y e a r l y water tempera- t u r e reg imes (Moore 1975 ) . Tarpon concentrate around heated power -p l a n t e f f l u e n t s du r i ng w i n t e r i n t he I n d i a n River , F l o r i d a (Snel son 1983).

E a r l y S t a g e I l a r v a e o f b o t h s p e c i e s occu r o n l y i n warm o c e a n i c w a t e r s (22.2-30.0 " C ; Wade 1962a ; E l d r e d and Lyons 1966; E l d r e d 1967, 1968, 1972; Be r r i en e t a1 . 1978; Smith 1980) , and i t appears p r o b a b l e t h a t such tempera tu res a r e necessa ry f o r proper development o f eggs and e a r l y 1 arvae.

M o f f e t t and Randa l l (1957) ex- posed j u v e n i l e t a r p o n (72-130 mm FL) he1 d a t 25-27 " C t o h igh temperatures i n l a b o r a t o r y t r i a l s . F i s h we re warmed from maintenance t o t e s t tem- peratures i n 3 hours. F i s h subjected t o 39.4-39.6 " C s u r v i v e d t h e 24-h t r i a l s ; those exposed t o 40.5-41.9 " C d i d n o t . I n a s e r i e s o f c o l d - to1 erance t r i a l s, j u v e n i l e tarpon (71- 130 mm FL) d i e d w i t h i n 24 h a t tem- pera tures o f 14.8-18.0 "C; o the rs sur- v i v e d t r i a l s a t 14.8-19.7 " C ( M o f f e t t and Randa l l 1957) . Tabb ( p e r s o n a l communication i n Wade 1962a) r e p o r t e d mor ta l i t y o f ta rpon i n Everglades Na- ti onal Park when w a t e r t e m p e r a t u r e decreased f rom 24 t o 11 " C w i t h i n a few hours. Rickards (1968) c o l l e c t e d

a s lugg ish j u v e n i l e ta rpon i n a Georgia s a l t marsh i n l a t e November when water t e m p e r a t u r e was 16.0 " C. C o n c u r - r e n t l y , several j u v e n i 1 es mai n t a i ned i n a s tee l h o l d i n g tank d ied ove rn igh t

when water tempera tures dropped f rom 21.0 t o 12.0 O C . However, Wade (1969) c o l l e c t e d j u v e n i l e tarpon a t tempera- t u res as low as 12 O C , and Gilmore e t a l . (1982) c o l l e c t e d t a r p o n a t 14 " C from a mosquito c o n t r o l impoundment i n eas tern F l o r i d a . Robins (1978) s ta ted t h a t t h e l o w e r l e t h a l temperature o f tarpon i s about 10 O C.

L a d y f i s h appear t o be s l i g h t l y more t o l e r a n t o f low temperatures than tarpon, judg ing by the 1 ower frequency o f f i s h - k i l l s (Storey 1937); they have been c o l l e c t e d a t temperatures o f 11.0 t o 35.0 O C ( H a r r i n g t o n 1958; Tagatz 1967; D a h l b e r g 1972; Rose e t a l . 1975).

Sal i n i ty

Throughout most o f t h e i r l i f e stages, tarpon and l a d y f i s h t o l e r a t e a wide range o f s a l i n i t i e s . However, e a r l y Stage I la rvae o f bo th species have been c o l l e c t e d on ly a t oceanic sal i n i t e s o f 28.5-39.0 p p t (Wade 1962a; Eldred and Lyons 1966; Eldred 1967, 1968, 1972; Be r r i en e t a1 . 1978; Smith 1980), and i t i s l i k e l y t h a t such concentrat ions are requ i red by eggs, yo1 k-sac larvae, and e a r l y Stage I la rvae o f both species f o r proper development.

B e y o n d S t a g e I, t a r p o n a n d 1 a d y f i s h a r e d e c i d e d l y e u r y h a l i ne. J u v e n i l e t a r p o n can w i ths tand d i r e c t t r a n s f e r from s a l t - t o f reshwater and v i c e - v e r s a ( B r e d e r 1944; M o f f e t t and Randal 1 1957 1. H a b i t a t s occupied by t a r p o n r a n g e f r o m f r e s h t o hype r - s a l i n e , o r 0 t o 47 p p t ( H i l d e b r a n d 1939; Simpson 1954; Mo f fe t t and Ran- d a l l 1957; Har r ing ton 1958; Har r ing ton and H a r r i n g t o n 1961; R i c k a r d s 1968; Wade 1969; Dahlberg 1972; Tagatz 1973; Tucker and Hodson 1976).

A l i kunh i and Rao (1951) c o l l e c t e d l a t e S t a g e I l a d y f i s h l a r v a e f r o m brack ish water (10.4 p p t ) and success- f u l l y t r a n s f e r r e d them d i r e c t l y t o f r e s h w a t e r (0 .08 p p t ) . J u v e n i l e 1 a d y f i s h h a v e been c o l l e c t e d a t

s a l i n i t i e s r a n g i n g f r o m 0.0 t o 45.0 p p t ( H a r r i n g t o n 1958; Har r ing ton and H a r r i n g t o n 1961; Herke 1969; Dahl berg 1972 ; G o v o n i a n d M e r r i n e r 1978; Thompson and Deegan 1982).

A d u l t l a d y f i s h a l s o t o l e r a t e a wide range o f s a l i n i t i e s , b u t appear l e s s l i k e l y t h a n t a r p o n t o occupy freshwater. We found no reference i n t h e 1 i t e r a t u r e s p e c i f i c a l l y r e p o r t i n g adu l t s from t r u l y freshwater. One o f us (A.V.Z.) has cap tu red l a d y f i s h i n t h e Lake George s e c t i o n o f t h e S t . Johns R i v e r , F l o r i d a , a t s a l i n i t i e s o f 0.5-2.0 ppt. Th is a r e a i s o f t e n as- sumea [ b y c o m p i l e r s e v a l u a t i n g s a l i n i t y requirements o f f i s h e s ) t o be f r e s h w a t e r because of i t s d i s t a n c e from the mouth o f the r i v e r (about 190 km) , b u t numerous s a l t spr ings main- t a i n r e 1 a t i v e l y h i g h s a l i n i t i e s . Tagatz (1967) c o l l e c t e d l a d y f i s h as f a r upstream as Palatka, F l o r i d a (135 km f r o m t h e m o u t h ) a n d r e p o r t e d s a l i n i t y there t o be 0 pp t ; however, he r e c o r d e d a l l s a l i n i t i e s l e s s than 1.0 p p t as 0 ppt. It i s l i k e l y t h a t a p p r e c i a b l e s a l i n i t i e s (perhaps >0.5 p p t ) are, i f n o t r e q u i r e d , t hen a t l e a s t p r e f e r r e d by l a d y f i s h .

Dissolved Oxvaen

Tarpon are o b l i g a t e a i r breathers ( t h e swimbl adder c o n t a i n s a1 v e o l a r t i s s u e ; S h l a i f e r 1 9 4 1 ) and a r e f requen t l y seen " r o l l i n g " a t the sur- face gu lp ing a i r ; when prevented from reaching the surface, they d i e w i t h i n 7 t o 128 h, even i n h i g h l y oxygenated water (Shl a i f e r 1941 1. A i r b rea th ing i s i m i t a t i v e l y m e d i a t e d by v i s u a l cues; j u v e n i l e s i n a school come t o t h e s u r f a c e i n r a p i d s u c c e s s i o n ( S h l a i f e r and Breder 1940; Sh l a i f e r 1941 1, perhaps t o reduce i n d i v i dua l suscepti b i 1 i t i e s t o predat ion by f i s h - e a t i n g b i r d s (Kramer and Graham 1976). The frequency o f a i r b reath ing i s i n - v e r s e l y c o r r e l a t e d w i t h d i s s o l v e d oxygen c o n c e n t r a t i o n ( S h l a i f e r and B rede r 1940; S h l a i f e r 1941) . A i r - b r e a t h i n g p r e c l u d e s m o r t a l i ty i n anox i c wa te rs and a l l o w s t a r p o n t o

s u r v i v e under c o n d i t i o n s de le te r i ous t o most f i s h e s . Tarpon have t h i s a b i l i t y a t l e a s t as e a r l y as t h e beg i n n i ng o f Stage I I 1 ( H a r r i ng ton 1966).

A i r b r e a t h i n g has n o t b e e n r e p o r t e d f o r l a d y f i s h , and i t i s un- l i k e l y t h a t i t occurs. "Ro l l i ng " has n o t been r e p o r t e d i n the l i t e r a t u r e . D i s s o l ved oxygen r e q u i r e m e n t s o f l a d y f i s h are unknown, b u t i t i s l i k e l y t h a t t h e s p e c i e s i s r e l a t i v e l y t o l e r a n t o f hypoxic condi t ions, as i t i s of ten found w i t h t a r p o n i n p o o r l y oxygenated h a b i t a t s . L a d y f i sh i n - h a b i t e d a c o a s t a l impoundment i n L o u i s i a n a i n wh ich d i sso l ved oxygen c o n c e n t r a t i o n s reached a minimum o f 1.0 mg/l (Rose e t a1 . 1975).

Contami nants

Aer ia l sp ray ing and ground f o g - g ing f o r nuisance i n s e c t c o n t r o l a r e w ide ly p rac t i ced i n F l o r i d a ' s c o a s t a l zone, and a g r i c u l t u r a l . pes t i c ides and herb ic ides used i n south F l o r i d a en te r c o a s t a l w a t e r s . R o b i n s ( 1 9 7 8 ) r e p o r t e d t h a t t a r p o n a r e e x t r e m e l y suscept ib le t o contaminants. Appl i ca - t i o n o f d i e l d r i n p e l l e t s i n a F l o r i d a s a l t marsh f o r the c o n t r o l o f 1 a r v a l s a n d f l i e s (Cu l i c o i d e s ) r e s u l t e d i n m o r t a l i t y o f l a d y t l sh a n d t a r p o n ( h a r r i ngton and Bid1 ingmayer 1958).

Turbi d i ty

Stage I l a r v a e o f b o t h l a d y f i s h and t a r p o n occu r o n l y i n c l e a r o f f - shore waters. Subsequent 1 i f e h i s t o r y stages appear t o be t o l e r a n t o f h i g h t u r b i d i t i e s . Hab i ta ts occupied, espe- c i a l l y by j u v e n i l e s , a r e g e n e r a l l y described as t u r b i d and dark-sta i ned.

Wet1 ands Dest ruc t ion and Dearadati on

Offshore and coastal h a b i t a t s o f v e r y y o u n g a n d a d u l t t a r p o n a n d l a d y f i s h a r e r e l a t i v e l y immune t o human- i nduced d e g r a d a t i o n . Con- versely, the es tuar ies , sal t marshes, and c o a s t a l mangroves used as nu r - ser ies by l a r v a l and j u v e n i l e l a d y f i s h and tarpon i n F l o r i d a are h i g h l y vu l - nerable t o changes induced by develop- ment. Robins (1978) d i scussed t h e var ious a c t i v i t i e s t h a t are degrad i ng tarpon nursery grounds i n F lo r i da ; h i s comnents are a lso app l icab le t o e a r l y 1 i f e h i s t o r y stages o f l ady f i sh , which share these h a b i t a t s . Among f a c t o r s r e s u l t i n g i n the des t ruc t i on o f nurs- e r y wet lands, he l i s t e d f i l l i n g o f w e t l ands, cana l i z a t i o n , bulkheading, c o n s t r u c t i o n o f water-1 i n e r i g h t - o f - ways and s t e e p - s i ded b o a t - a c c e s s f inger-canal s, and impoundment o f wet- 1 ands f o r mosquito con t ro l . Progress has r e c e n t l y been made i n amel io ra t ing t h e e f f e c t s o f i m p o u n d m e n t f o r mosqu i to c o n t r o l because impoundment does n o t n e c e s s a r i l y r e s u l t i n t h e dest ruc t ion o f wet l ands. Rather, i m - pounded wet l ands, i f proper ly managed, can r e t a i n the b e n e f i c i a l cha rac te r i s- t i c s o f na tura l wet l ands whi 1 e prov id- i ng a d e q u a t e m o s q u i t o c o n t r o l (Clements and Rogers 1964; P r o v o s t 1973). However, access t o these wet- l a n d s (and subsequent o p p o r t u n i t i e s f o r e g r e s s ) by l a r v a l and j u v e n i l e t a r p o n and 1 a d y f i s h i s p r e c l u d e d o r severely c u r t a i l e d by reduced o r non- e x i s t e n t exchange w i t h e s t u a r i ne w a t e r s (Wade 1969; G i 1 more e t a1 . 1982; Har r i ngton and Har r i ngton 1982). I m p r o v e d impoundment m a n a g e m e n t s t r a t e g i e s , aimed a t enhanc ing ex- change r a t e s , have been proposed by Clements and Rogers (1964) , P r o v o s t (1973) , Montague e t a1 . (19851, and Lewis e t a l . (1985).

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Eldred, B. 1968. F i r s t r eco rd o f a 1 a r va l tarpon, Mega1 ops a t 1 a n t i c u s V a l e n c i e n n e s , f r o m t h e G u l t o f Mexico. F l a . Boa rd Conserv. Mar. Lab. L e a f l . Ser. 4 (7 ) . 2 pp.

Eldred, B. 1972. Note on l a r v a l t a r - pon, Mega1 ops a t 1 a n t i c u s (Mega- 1 o p i d a e ) i n t h e t r a i t s . F l a . Dep. Nat. Resour . Mar. Res. Lab. L e a f l . Ser. 4(22) . 6 pp.

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s i x species o f f i s h e s c o l l e c t e d f rom pon, Mega1 ops a t1 a n t i c a Valenciennes a sub t rop i ca l s a l t marsh from eas t from t r a n s i t i o n a l stage through on- c e n t r a l F l o r i da , U.S.A. F la . Sc i . s e t o f s c a l e f o r m a t i o n . Cope ia 4 9 ( S ~ p p l . 1) : 18. 1958: 1-10.

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4. Title and Subtle Species P r o f i l e s : L i f e H i s t o r i e s and Environmental Requirements o f Coastal Fishes and I n v e r t e b r a t e s (South F l o r i d a ) -- Lady f i sh

so272 - 101

and Tarpon

REPORT WCUMENTAllON 1. RE*m t PAGE I B i o l o g i c a l Report 82(11.104)*I

7. Author(,)

Alexander V. Zale and Susan G. M e r r i f i e l d

3. Rulplent's Acenslon No.

9. Performing Omniratlon Name and M d m s

Oklahoma Cooperat ive F i s h and Wi ld1 i f e Research U n i t 404 L i f e Sciences Nest Oklahoma S t a t e U n i v e r s i t y S t i l lwa te r , OK 74078

12 Sponsoring Omnlzation Name and Addms

Nat iona l Wetlands Research Center U.S. Army Corps o f Engineers F i sh and W i l d l i f e Serv ice Waterways Experiment S t a t i o n U.S. Dept. o f t he I n t e r i o r P.O. Box 631 Washington, DC 20240 Vicksburg, MS 39180

5. Report Dote

J u l y 1989

8. Performing Or#onlration Rept. No.

10. Rol.ct/TasklWorlc Unit No.

11. M n e t ( C ) or GrantfG) No.

(C)

(GI

1% Typa of Report & Period Cowred

IS. Supplementary Not..

* U.S. Army Corps o f Engineers Report No. TR EL-82-4

16. Abrtract (Limit: 200 word.)

Species p r o f i l e s a re l i t e r a t u r e summaries o f t h e taxonany, morpholoqv, d i s t r i b u - t i o n , l i f e h i s t o r y , h a b i t a t s , and environmental r e q u i r e m n t s o f c o a s t a l spec ies o f f i s h e s and aqua t i c i n v e r t e b r a t e s . They a re designed t o a s s i s t i n env i ron - mental impact assessment. The ta rpon and l a d y f i s h a r e popu lar g a m f i s h e s . A d u l t s spawn o f f sho re . Larva l and j u v e n i l e stages i n h a b i t coasta l marshes and mangroves. Both spec ies a re t h e r m o p h i l i c ( p r e f e r r i n g warm water ) , e u r y h a l i n e ( t o l e r a n t o f a wide range o f s a l i n i t y ) , and a re capable o f s u r v i v i n g a t low oxygen concen t ra t i ons . Wetlands d e s t r u c t i o n and degradat ion n e g a t i v e l y a f f e c t t hese spec ies by reduc ing nursery areas.

17. Document Analysis a. Dorripton

F i shes F i s h e r i e s L i f e cyc les Es tua r ies Temperature Feeding h a b i t s Sal i n i ty Growth Oxygen

b. Identitienl0p.n-Ended Terms

Tarpon Troph ic ecology Megalops a t l a n t i cus Spawni ng L a d y f i sh Envi ronmental requ i rements Elops saurus

I la Availablllty Stakmen: I 19. Suurlty Class (This Report) 1 21. No. of PWW I

OFrIONAL FORM 272 (4-77) (Formerly NTiS35)

U n l i m i t e d

Dopartm.nt of Commerce

U n c l a s s i f i e d 20. Suurlty Class (This Pago)

U n c l a s s i f i e d

17 n. PAC.

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