AGE, GROWTH AND MORTALITY OF GREATER AMBERJACK FROM THE SOUTHEASTERN UNITED-STATES

Rings on 323 sectioned otoliths (sagittae) were used to determine the ages of greater amberjack, Seriola dumerili, sampled from headboats an d commercial handline vessels operating out of ports from North Caroli na through the Florida Keys. Age and growth determinations were diffic ult. Rings were identified and counted on 71% of the samples, but meas urements could be made on only 48%. The oldest fish examined was 17 ye ars old and was 1552 mm total length (TL). Back-calculated mean length s at annulus formation were 366, 873, 1207 and 1471 mm TL for ages 1, 5, 10 and 15, respectively. The von Bertalanffy equation describing th eoretical growth for TL was L-t = 1648(1 - e(-0.119(t + 1.230))), wher e t = years. The equation using fork lengths (FL) was L-t = 1514(1 - e (-0.115(t + 1.178)). The weight-length relationship for greater amberj ack was W = 7.2 X 10(-8)L(2.700), where W is the whole fish weight (in kg), and L is the total length (in mm). Conversion of total length to fork length may be obtained using the equation: FL = -4.807 + 0.887(T L), and fork length to total length: TL = 20.110 + 1.111(FL). Greater amberjack are fully recruited to the fishery by age 8. Estimates of to tal instantaneous mortality (Z) ranged from 0.60 to 0.65 depending on the year. (C) 1997 Elsevier Science B.V.