We examined 1005 cobia, Rachycentron canadum, from recreational catches in the northeastern Gulf of Mexico from 1987 to 1995. Specimens ranged from 325 to 1651 mm fork length (FL); females had a mean FL of 1050 mm (n=730) and were significantly larger than males that had a mean FL of 952 mm (n=275). The over all male to female ratio was 1:2.7. Ages of 565 cobia were estimated from thin-sectioned otoliths (sagittae). Marginal-increment analysis of sagittal otoliths showed a single annual minimum during June. Male cobia (n=170; 525-1330 mm FL) ranged from age 0 to 9, and females (n=395; 493-1651 mm FL) ranged from age 0 to 11. The relationship of observed fork length and age was described by the von Bertalanffy growth equation for males FLt = 1171(1-exp [-0.432(t+1.150)]) and for females FLt = 1555(1-exp [-0.272(t+1.254)]). Growth in length for both sexes was relatively fast through age 2, after which growth slowed gradually. Estimates of the von Bertalanffy growth equation parameters L-infinity and K were significantly different for males and females, whereas estimates for t(0) were not significantly different. Sagittal otolith weight was a good predictor of age. The instantaneous rate of total mortality (Z) estimated by catch curve analysis for fully recruited ages 4-8 was 0.75.
Franks, J. S.,
Warren, J. R.,
Buchanan, M. V.
(1999). Age and Growth of Cobia, Rachycentron canadum, from the Northeastern Gulf of Mexico. Fishery Bulletin, 97(3), 459-471.
Available at: http://aquila.usm.edu/fac_pubs/4667