Age and Growth of the Bull Shark, Carcharhinus leucas, from Southern Gulf of Mexico

A. Cruz-Martínez¹

X. Chiappa-Carrara²

²Present address: Unidad Académica Sisal, Sisal, Yucatán, National Autonomous University of Mexico
Marine Ecology Research Unit, FES-Z, National Autonomous University of Mexico

V. Arenas-Fuentes³

³ Present address: Ecology and Fisheries Center, Universidad Veracruzana

Institute of Marine Sciences and Limnology, National Autonomous University of Mexico,

Ciudad Universitaria, 04510 México D.F.

CRUZ-MARTÍNEZ, X. CHIAPPA-CARRARA, V. ARENUS-FUENTES. 2005. Age and Growth of the Bull Shark, Carcharhinus leucas, from Southern Gulf of Mexico. J. Northw. Atl. Fish. Sci., 35: 367-374. https://doi.org/10.2960/J.v35.m481

Abstract

Age and growth of bull shark, Carcharhinus leucas, was investigated in the southern Gulf of Mexico (Veracruz and Campeche, Mexico) from December 1993 through June 1997. Ninety-five specimens were obtained from commercial fishery catches, and vertebrae were examined from 20 males, 61 females and 14 individuals unidentified to sex. Vertebrae were examined using five different techniques to enhance the visibility of growth rings: i) alizarin red stain, ii) crystal violet stain, iii) X-ray, iv) silver nitrate stain, and v) without staining. Verification of temporal growth ring formation was done by the indirect method of marginal increment analysis. An isometric relationship was found between growth and length of centrum, is described by a linear equation. Age-at-maturity was 10 years (204 cm total length, TL) for females and 9-10 years (190-200 cm TL) for males. The oldest female was 28 (256.0 cm TL), and the oldest male was 23 (243.0 cm TL). The von Bertalanffy growth parameters were estimated for the species (L_∞ = 256.4 cm TL, k = 0.1397 per year and t_o = -1.935), for males (L_∞ = 248.4 cm TL, k = 0.1692 per year and t_o = -1.03), and for females (L_∞ = 262.1 cm TL, k = 0.1235 per year and t_o = -2.44). Sexual differences for each particular growth curve were found, L_∞ being the parameter that showed the greatest difference between males and females; females attain a larger size.

Key words: Age, ageing methods, Carcharhinus leucas, growth, length maturity, vertebrae

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