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

During 1986-91, we examined 2088 common snook. Centropomus undecimalis, cap tured in Jupiter and Lake Worth inlets and adjacent waters on the east coas t of Florida and 1784 common snook captured in Tampa Bay on the west coast of Florida. Of fish that were sexed, females ranged in length from 397 to 1 105 mm FL. and males ranged from 124 to 925 mm FL. East coast fish were lar ger overall than west coast fish. Age of common snook was determined from s ectioned otoliths. Results from the return of 80 oxytetracycline-marked oto liths 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, bu t most of the fish in our sample were from 1 to 7 years old. The von Bertal anffy growth models were significantly different (P<0.001) for each coast a nd suggested that east coast snook grow faster than west coast snook. Commo n snook are protandric hermaphrodites. The gonads of 27 transitional specim ens contained both degenerating spermatogenic and developing ovarian tissue , and sex reversal was observed in captive common snook. Common snook sex r atios and length-frequency distributions were also consistent with a diagno sis of protandric hermaphroditism. Females smaller than 500 mm FL were unco mmon, and only one female less than 400 mm long was captured. The predicted lengths and ages at which 50% of the fish in the population would be femal es were 767 mm FL and 7.4 years for the east coast and 608 mm FL and 5.1 ye ars for the west coast. Some males on both coasts were sexually mature at l engths less than 200 mm FL and at age 0; most age-1 males were mature on bo th coasts. All females were considered mature because they were derived fro m postspawning males.