Age, Growth, and Reproduction of Greater Amberjack off the Southeastern U.S. Atlantic Coast

Abstract

AbstractThe greater amberjack Seriola dumerili is a pelagic, epibenthic species that is widely distributed in the Atlantic, Pacific, and Indian oceans. Life history samples from a total of 2,729 greater amberjacks were collected between 2000 and 2004 by personnel of the Marine Resource Monitoring Assessment and Prediction program and National Marine Fisheries Service port agents from recreational fisherman and in commercial fish houses from Cape Lookout, North Carolina, to Key West, Florida. Ages were estimated using thin transverse otolith sections from 1,996 specimens; sex and reproductive state were assigned to 2,517 fish based on histological preparations of gonadal tissues. Ages of greater amberjacks sampled ranged from 1 to 13 years; these data were described with a von Bertalanffy growth equation fitted to all aged specimens: Lt = 1,241.5 × [1 − e−0.28(t+1.56)]. Sexual dimorphism was evident; females were larger at age than males. Size at 50% maturity was 644 mm fork length (FL) for males and 733 mm FL for females. Age at 50% maturity for females was 1.3 years. Estimates of potential annual fecundity ranged from 18,271,400 to 59,032,800 oocytes for 930‐1,296‐mm specimens and from 25,472,100 to 47,194,300 oocytes for ages 3‐7. Peak spawning occurred primarily off south Florida and the Florida Keys during April and May. Even though the extremely fast growth, early maturation, very high fecundity, and wide distribution of greater amberjacks suggest that the population would be difficult to overexploit, a recent stock assessment of the Gulf of Mexico population shows that the species is vulnerable to overexploitation and should managed more conservatively than the life history characteristics imply.