Tarpon, continued 



waters and finally to the ocean (Wade 1969). This 

 move typically occurs when juveniles reach approxi- 

 mately 400 mm SL, after nearly one year of growth 

 (Killam et al. 1 992). It could be speculated that this shift 

 in habitat occurs after tarpon reach a sufficient size to 

 avoid most predators, or it may be related to the the 

 increasing food requirements of juveniles. Adult and 

 large juvenile tarpon are capable of extensive move- 

 ments, but patterns of coastal migration other than 

 inshore-offshore movements in response to the sea- 

 sonal temperature changes are not evident (Randall 

 1959, Hildebrand 1963, Moe 1972). Adult tarpon are 

 reported to be most abundant in inshore waters from 

 April to November (Breuer 1 949, Hoese 1 958, Springer 

 and Pirson 1958). Assemblages of sexually maturing 

 tarpon during spring and summer may be preparatory 

 to an offshore spawning migration from the inshore 

 feeding areas (Moe 1 972, Crabtree et al. 1 992, Killam 

 et al. 1 992). They have been observed in large schools 

 2-5 km offshore, swimming together in a circular mo- 

 tion referred to as a "daisy chain" (Crabtree et al. 1 992). 

 These schools can range from 25 to more than 200 

 individuals. Based on collections of larvae (Crabtree et 

 al. 1 992, Crabtree 1 995), it has been inferred that adult 

 tarpon migrate from inshore feeding areas to offshore 

 (up to 250 km) spawning areas from May through July. 



Reproduction 



Mode : This species has separate male and female 

 sexes (gonochoristic), and fertilization is external 

 through the release of milt and roe into the water 

 column. 



Spawning : The exact locations of spawning areas are 

 not well known. They are apparently restricted to 

 offshore waters such as the east coast of Florida to 

 Cape Hatteras, Florida Straits, west central Florida, 

 southwestern Gulf of Mexico, outer continental shelf 

 and slope of the eastern Gulf of Mexico, Gulf Stream, 

 and Caribbean Sea. Spawning activity has not been 

 documented, but adult tarpon have been observed in 

 large schools or aggregations known as "daisy chains" 

 off of the Florida Gulf Coast (Crabtree et al. 1992). 

 Larvae with estimated ages of 2 to 25 days have been 

 collected over the continental shelf and slope of the 

 Florida Gulf coast, indicating spawning in the immedi- 

 ate vicinity (Crabtree et al. 1992). Similar exhaustive 

 larval sampling efforts have not yet occurred in the 

 northwest Gulf of Mexico, the Yucatan Peninsula, or 

 elsewhere, so other spawning locations remain un- 

 known (Cyr pers. comm.). The estimated spawning 

 season of Florida tarpon is from April to July, with near 

 ripe females and milt producing males occurring in 

 March and April respectively, and spent females occur- 

 ring in July and August (Breder 1 944, Hildebrand 1 963, 

 Eldred 1967, Jones et al. 1978, Randall 1969, Wade 

 1969, Smith 1980, Crabtree et al. 1992, Killam et al. 



1992, Cyr pers. comm.). Crabtree et al. (in press) 

 reported that spawning of tarpon in the tropical waters 

 of Costa Rica is not seasonal, and that reproductively 

 active females were caught during all months. 



Fecundity : One female tarpon, 2,032 mm, was re- 

 ported to contain approximately 12,202,000 eggs 

 (Babcock 1 936, Wade 1 962). Crabtree et al. (in press) 

 examined the gonads of 737 Florida tarpon, and re- 

 ported that fecundity ranged from 4.5 to 20.7 million 

 oocytes per female, and that fecundity is positively 

 correlated with fish weight. 



Growth and Development 



Egg Size and Embryonic Development : No information 

 is available on ripe eggs, but ovarian eggs in spent 

 females were non-adhesive, opaque, and ranged 0.6 

 to 1.7 mm in diameter (Randall 1959, Wade 1962). 

 Fertilized eggs have not been successfully collected 

 and identified (Crabtree 1995). 



Age and Size of Larvae : Larval development is often 

 described in three stages: Stage I, a fully formed 

 leptocephalus; Stage II, a period of marked shrinking 

 during which the larva gradually loses its leptoceph- 

 alus form; Stage III, begins with a second period of 

 length increase and ends with the onset of the juvenile 

 stage (Wade 1 962). Larvae are reported to occur in the 

 Gulf of Mexico from June through August (Ditty et al. 

 1988). Crabtree et al. (1992) described the age, size, 

 and growth of tarpon leptocephalus larvae collected off 

 of the Florida Gulf Coast. These collections occurred 

 over depths ranging from 90 to 1 ,400 m, at sea surface 

 temperatures of 27 to 30°C, and salinities of 35 to 36%<>. 

 In June 1981 a total of 54 larvae were collected, 

 ranging from 7.3 to 23.8 SL. In 1989, a total of 275 

 larvae were collected, ranging from 5.5 to 24.4 mm SL, 

 and with an estimated age of two to 25 days. Based on 

 the collected specimens, standard length (in mm) and 

 age (in days) can be described by the equation SL = 

 2.78 + 0.92(age). Estimated size at hatching was 2.78 

 ± .63 mm, and estimated hatching dates were from 

 May 12 to July 10. Based on back-calculation of 

 hatching dates, it can be inferred that peak hatching 

 activity occurs approximately one week after a full 

 moon, and one week after a new moon (Crabtree 

 1995). Alternately, it is possible that larval survival, not 

 spawning activity, is associated with lunar phase 

 (Crabtree 1995). 



Juvenile Size Range : The minimum size described for 

 juveniles is 25.2 mm SL (Wade 1 962). Juvenile growth 

 is seasonal, averaging about 30 mm per month during 

 the summer and early fall (Rickards 1 968, Killam et al. 

 1992). Cyr (1991) examined length-frequencies of 

 juvenile tarpon from the east coast of Florida, and 

 found that average first year growth (October to Octo- 



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