Age and growth of spinner sharks, Carcharhinus brevipinna, in the western North Atlantic Ocean

Abstract

The age and growth of the spinner shark, Carcharhinus brevipinna, was investigated throughout its range in coastal waters of the western North Atlantic Ocean off the United States. A total of 769 vertebrae (341 males and 428 females) were collected from fishery independent and dependent sampling efforts between 1986 – 2022 and processed to estimate ages and generate growth models. Maximum observed age estimates for males and females were increased to 23.5 and 21.5 years, respectively. Sizes ranged from 482 to 1790 mm fork length (FL) for males and 410 mm to 2006 mm FL for females. All age and length data were fit to logistic, Gompertz, and von Bertalanffy models, with the three parameter von Bertalanffy model producing the best fit. Significant differences were detected between female and male model parameters with female models producing higher theoretical maximum size and lower growth constant (L∞ = 1980 mm FL, k = 0.12, to = -3.26 years) than males (L∞ = 1789 mm FL, k = 0.15, to = -2.96 years). Spatial differences in growth were also detected for females and males with spinner sharks off the east coast of the United States reaching larger asymptotic lengths but similar growth rates and size at birth relative to conspecifics in the northern Gulf of Mexico.