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

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.

Using local ecological knowledge to identify shark river habitats in Fiji (South Pacific)

“…These morphological characteristics match juvenile bull sharks. Bull sharks are born at a size of 56-81 cm (Cruz-Martínez et al 2005) and data from the northern hemisphere suggest that they spend their first year within riverine nursery areas in lower salinity waters further upriver before they move towards the river mouths and out into coastal areas (Simpfendorfer et al 2005). Based on the villagers' descriptions and information on bull shark occurrence in similar habitat types elsewhere (Pillans & Franklin 2004;Heupel & Simpfendorfer 2008;Thorburn & Rowland 2008;Heithaus et al 2009;McCord & Lamberth 2009;Ortega et al 2009), the hypothesis that juvenile and possibly adult bull sharks occur in and use riverine waters in Fiji cannot be rejected and warrants further investigation.…”

New record of Carcharhinus leucas (Valenciennes, 1839) in an equatorial river system

“…It was not possible to analyze the specimen before the fishermen processed it. However, based on studies of Compagno et al (2005) and Cruz-Martinez et al (2005) female individuals mature between 1800 mm and 2300 mm TL. Taking this into account, the approximate TL or this specimen suggests that it was not yet mature.…”

Comparative Feeding Ecology of Bull Sharks (Carcharhinus leucas) in the Coastal Waters of the Southwest Indian Ocean Inferred from Stable Isotope Analysis

“…All sampled sharks were measured in situ using laser photogrammetry [48] and ranged in size from 1.6 - 2.5m TL (2m ±0.3, mean ±SD). Bull sharks were then grouped into sub-adults (1.6m-2.2m) and adults (2.2m-2.5 TL) based on the approximate length at sexual maturity (c. 2.2m TL) according to the literature [26,49-51]. …”