AGE AND GROWTH-ESTIMATES FOR THE DUSKY SHARK, CARCHARHINUS-OBSCURUS, IN THE WESTERN NORTH-ATLANTIC OCEAN

Age and growth of the dusky shark, Carcharhinus obscurus, was estimated from bands in the vertebral centra of 122 individuals and from length-frequency data from 341 individuals. The von Bertalanffy growth function parameters from the vertebral analysis were considered more robust (L(infinity) = 373, K = 0.038, t0 = -6.28, male; L(infinity) = 349, K = 0.039, t0 = -7.04, female). Comparison of male and female growth curves generated from vertebral data indicate a statistically significant difference; however, these differences are due primarily to larger sizes attained by adult females. Estimates of age at maturity indicate that dusky sharks follow the typical carcharhinid pattern of slow growth and late age at maturity. The size at maturity is reported at 231 cm FL and 235 cm FL for males and females, respectively. These lengths correspond to approximately 19 years for males and 21 years for females. The oldest fish aged from vertebrae was a 33+ year-old female.