Age, growth, maturation, and protandric sex reversal in common snook, Centropomus undecimalis, from the east and west coasts of South Florida


Taylor, Ronald G., James A. Whittington, Harry J. Grier, and Roy E. Crabtree
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During 1986–91, we examined 2088 common snook, Centropomus undecimalis, captured in Jupiter and Lake Worth inlets and adjacent waters on the east coast of Florida and 1784 common snook captured in Tampa Bay on the west coast of Florida. Of fi sh that were sexed, females ranged in length from 397 to 1105 mm FL, and males ranged from 124 to 925 mm FL. East coast fi sh were larger overall than west coast fi sh. Age of common snook was determined from sectioned otoliths. Results from the return of 80 oxytetracycline-marked otoliths combined with analyses of monthly patterns in marginal increments and the percentage of otoliths with an annulus on the edge, demonstrated that a single annulus is formed each year. Common snook can live to 21 years, but most of the fi sh in our sample were from 1 to 7 years old. The von Bertalanffy growth models were significantly different (P<0.001) for each coast and suggested that east coast snook grow faster than west coast snook. Common snook are protandric hermaphrodites. The gonads of 27 transitional specimens contained both degenerating spermatogenic and developing ovarian tissue, and sex reversal was observed in captive common snook. Common snook sex ratios and length-frequency distributions were also consistent with a diagnosis of protandric hermaphroditism. Females smaller than 500 mm FL were uncommon, and only one female less than 400 mm long was captured. The predicted lengths and ages at which 50% of the fi sh in the population would be females were 767 mm FL and 7.4 years for the east coast and 608 mm FL and 5.1 years for the west coast. Some males on both coasts were sexually mature at lengths less than 200 mm FL and at age 0; most age-1 males were mature on both coasts. All females were considered mature because they were derived from postspawning males.