On the Biology of Florida East Cost Atlantic Sailfish, 

 (Istiophorus platypterus)' 1 



JOHN W. JOLLEY. JR. 2 



ABSTRACT 



The sailfish, Istiophorus platypterus, is one of the most important species in southeast Florida's marine 

 sport fishery. Recently, the concern of Palm Beach anglers about apparent declines in numbers of sailfish 

 caught annually prompted the Florida Department of Natural Resources Marine Research Laboratory to 

 investigate the biological status of Florida's east coast sailfish populations. 



Fresh specimens from local sport catches were examined monthly during May 1970 through September 

 1971. Monthly plankton and "night-light" collections of larval and juvenile stages were also obtained. 

 Attempts are being made to estimate sailfish age using concentric rings in dorsal fin spines. If successful, 

 growth rates will be determined for each sex and age of initial maturity described. Females were found to be 

 consistently larger than males and more numerous during winter. A significant difference in length-weight 

 relationship was also noted between sexes. 



Fecundity estimates varied from 0.8 to 1.6 million "ripe" ova, indicating that previous estimates (2.5 

 to 4.7 million ova) were probably high. Larval istiophorids collected from April through October coincided 

 with the prominence of "ripe" females in the sport catch. Microscopic examination of ovarian tissue and 

 inspection of "ripe" ovaries suggest multiple spawning. 



Florida's marine sport fishery has been valued as a 

 $200 million business (de Sylva, 1969). Atlantic sail- 

 fish, Istiophorus platypterus (Shaw and Nodder), 

 range throughout coastal waters and reside year- 

 round in Florida where they are prominent among 

 some 50 species of marine sport fishes. Sailfishing on 

 Florida's east coast became popular during the 

 1920's and 1930's (Voss, 1953). Sailfish have been 

 categorized as the most sought-after species by 

 southeast coast marine charter boat anglers (Ellis, 

 1957). In addition, Ellis showed that sailfish were 

 taken on 20% of the fishing trips sampled, but made 

 up only 3 to 5% of the total numbers offish caught. 

 McClane (1965) estimated that more than 1,000 sail- 

 fish were caught each year between Stuart and Palm 

 Beach : thus , this area became known as the ' ' sailfish 

 capital of the world." 



The University of Miami Marine Laboratory 

 (now Rosenstiel School of Marine and Atmospheric 

 Sciences) initiated studies on the biology of sailfish 



'Florida Department of Natural Resources Marine Research 

 Laboratory Contribution No. 208. 



2 Florida Department of Natural Resources Marine Research 

 Laboratory, 100 Eighth Avenue SE, St. Petersburg, FL 33701. 



in 1948 at the request of the Florida Board of Con- 

 servation (now Florida Department of Natural Re- 

 sources [FDNR]). Voss (1953, 1956) described post- 

 larval and juvenile stages and discussed the general 

 biology of Florida's sailfish populations. De Sylva 

 (1957) described age and growth from length fre- 

 quencies from the sport catch (Petersen method), 

 but suggested the results be checked by a more con- 

 ventional method; specifically, annular marks. 

 Further, de Sylva found a wide range in weight for a 

 given length and age, suggesting the possibility of 

 differential growth and/or mortality of sexes. Gross 

 morphology and histology of gonads from Indian 

 Ocean billfishes were described by Merrett (1970), 

 but a thorough understanding of maturational cycles 

 in Atlantic sailfish has yet to be obtained. 



Florida's interest in the species was renewed in 

 March 1970 by local concern for the welfare of the 

 Palm Beach sailfishery. John Rybovich. Jr., repre- 

 senting local charter boat captains and anglers, ex- 

 amined catch statistics compiled by the West Palm 

 Beach Fishing Club and Game Fish Research As- 

 sociation, Inc., and noted that the yearly catch of 

 "gold button" sailfish (specimens eight feet or 



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