Abstract

Wahoo, Acanthocybium solandri, are important in the recreational fishery throughout the Gulf of Mexico and Caribbean. However, there is limíted information on the basic biology of this species. We obtained gonadal samples from 70 wahoo captured during fishing toumaments in the northem Gulf of Mexico during June - September of 1997 and May - June of 1998 and from 32 wahoo captured in November 1997 at Bimini, Bahamas. Mean GSI values of females were elevated from May to August and peaked in June. Histological analysis and oocyte frequency dístributions revea1ed that wahoo are multiple spawners wíth asynchronous oocyte development throughout the spawníng season. Ovaries in the late developing stage occurred in all months but September. However, 10% of the females captured in June had regressed ovaries, suggesting there may be a group of wahoo that do not spawn during the summer. Females from Biminí were eíther regressed (85%) or beginníng early ovarian development (15%). Three Gulf females wíth hydrated oocytes were analyzed for estimates of batch fecundity; the mean relative batch fecundíty was 57.7 :t: 5.4 eggs/g ovary-free body weight. Spawning frequency estimates for June, determined from the percentage of fish wíth either hydrated oocytes, oocytes undergoing final oocyte maturation or post ovulatory follieles in the ovary, indicate wahoo may spawn once every 2 - 6 days. The estímated size at 50% maturity for female wahoo is 1,020 mm FL, corresponding to an estimated age of two years. In contrast, all male wahoo captured were sexually mature, suggesting size at 50% maturity for males is < 935 mm FL. Males have an extended reproductive season compared to females; the majority of males captured from June - September were runníng ripe and all males captured in November from Bimini had testis containing spermatozoa. Although the data available provide preliminary information on the reproductíon of wahoo, many questíons remain. The most intriguing concems the possibility of two temporally different spawning groups of female wahoo.

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