Age and growth of the tiger shark, Galeocerdo cuvier (Péron & Lesueur, 1822) from the equatorial South Atlantic Ocean

Abstract

Age and growth in the tiger shark, Galeocerdo cuvier, were estimated from vertebral analysis of specimens collected in Brazil. A total of 221 sharks (82 to 426.3 cm total length - LT) were measured, and among these sharks, vertebrae were collected from 67 individuals, and more 9 of embryos (68 - 77 cm LT) were added to total sample for analysis. Monthly mean marginal increment and the frequency of opaque rings in the edge of vertebrae did not allow the observation of periodicity; nonetheless, growth bands were considered to be annual. No significant differences in size, age or growth were found between sexes. Based on the Akaike Information Criterion (AIC), the von Bertalanffy model was the most adequate to describe the growth of G. cuvier. The estimated parameters for both sexes were: L∞ = 401.2 cm LT, k = 0.255 year-1 and t0 = -1.08 years. The age of sampled individuals ranged between 0 and 13.5 years, with sexual maturation being estimated at 310 cm LT or 4.7 years. Overall, the species exhibited rapid growth, particularly during the juvenile stage. Differences in sizes and ages were found in specimens suggesting an ontogenetic habitat shift from coastal to oceanic waters.