Abstract

The wahoo, Acanthocybium solandri, is an oceanic, migrotory, pelagic fish that occurs in most tropical and subtropical seas of the world. In the westem AtIantic Ocean wahoo occur from New Jersey to Columbia, incIuding Bermuda, the Bahamas, the Caribbean Sea and the Gulf of Mexico (Gulf). Although wahoo support recreational and comrnercial fisheries in the northem Gulf, life history data for stock assessment are lacking. Dorsal fin spines #1-5 removed from wahoo caught in the northem Gulf during June-September 1997 and MayJune 1998, and at Bimini, Bahamas in November 1997 were assessed to determine their potential for age estimation. Transverse thin-sections of spines were viewed under transmitted light at 25 - 40x rnagnification. Spines #2-5 generally revealed a substantially eroded central matrix surrounded by ambiguous markings, which fundamentally rendered them ineffective as ageing structures. First dorsal spines (the largest of the spines examined) exhibited a partially eroded aml/or vascularized central matrix with a succession of altemating, reasonably well-defined opaque and translucent bands. Though not yet validated as annuli, we speculated that translucent bands (typically comprised of multiple small rings) on first dorsal spine sections were probable indicators of age and enumeroted them for 38 males (935 - 1,390 rnm FL) and 47 females (875 1,803 mm FL). Extensive vascularization of the centrol matrix in spines from six fish (females), range 1,43 - 1,803 mm FL, completely obscured the inner tmnslucent bands, which required their statistical replacement Band counts for the spines examined ranged from 1 - 6. Mean length-at-estimated age data were derived separately for Gulf and Bimini specimens.

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