On the Biology of Florida East Coast Atlantic Sailfish, (Istiophorus platypterus)

Jolley, Jr., John

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.