Untitled Document

ABSTRACT

A total of 1928 specimens were sampled from commercial catches off North Carolina between December, 1996 and September 1999. An additional 218 samples were obtained with fishery-independent gear. Red groupers ranged in total length (TL) and age from 315 to 851 mm TL and from 2 to 20 years. Marginal increment analysis indicated that annulus formation occurred during the late summer. TL at age was described by the following von Bertalanffy growth equation: TL (mm) = 853(1-exp (-0.209(age (yrs)+0.812))). Sex and reproductive stage of 2068 red groupers were assessed by histological analysis. Of these, 86.8% were classified as females, 5.9% as transitionals, and 7.3 % as males. Age at 50% maturity was 2.36 years and TL at 50% maturity was 487.2 mm. The sex ratio of red grouper was significantly different from 1:1 in favor of females. Spawning females, recognized by the presence of migratory nucleus oocytes, hydrated oocytes and post-ovulatory follicles, were found between February and June. Red groupers are protogynous. Age at 50% transition was 7.24 years old and TL at 50% transition was 690.4 mm. Catch curve analysis of fishery-dependent data indicated that fishing mortality in 1998 was 0.75 and that red groupers are fully recruited to the fishery at age 4. A model was developed to estimate yield per recruit and sex-specific spawning biomass per recruit including release mortality and sex ratio compensation. Female SPR was 0.18 and male SPR was 0.22, suggesting that the red grouper population off the Carolinas is overfished.