Age, growth, and maturation of the Finetooth Shark

Age, growth, and maturation of the Finetooth Shark, Carcharhinus isodon, in the Western North Atlantic Ocean

Elizabeth A. Vinyard, Bryan S. Frazier, J. Marcus Drymon, James J. Gelsleichter, Walter J. Bubley

ABSTRACT:

Many elasmobranchs display K-selected life history characteristics, making species-specific life history parameters critical to development of the most accurate stock assessment models. Age, growth, and maturity were examined for Finetooth Sharks, Carcharhinus isodon, in coastal waters of the Western North Atlantic Ocean (WNA) from Winyah Bay, South Carolina to Cape Canaveral, Florida. Ages were estimated from the vertebrae of 200 males and 232 females. The maximum observed age for males and females was 21.9 years and 22.3 years, respectively. Sizes ranged from 376 mm to 1174 mm fork length (FL) for males and 380 mm to 1282 mm FL for females. Significant differences were detected between the sexes necessitating sex-specific von Bertalanffy growth models yielding the following parameters: male, L_∞ = 1140 mm FL, k = 0.29, L₀ = 460 mm FL; female, L_∞ = 1253 mm FL, k = 0.20, L₀ = 464 mm FL. Median length (L₅₀) at maturity was 1010 mm FL for males and 1043 mm FL for females corresponding to an age at median maturity (A₅₀) of 6.6 years and 6.8 years, respectively. Significant differences in growth and maturity were detected between the current study and previously published parameters for the WNA and Gulf of Mexico (GOM). Observed differences in the WNA were driven by ageing methods, with current methods yielding significant differences in age estimates between studies. Results from the current study, in conjunction with previously published reproductive, tag-recapture and genetic studies, provide support for separate stocks between the WNA and GOM.

Environ Biol Fish (2019), DOI: 10.1007/s10641-019-00929-9

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