Age and growth of the tiger shark Galeocerdo cuvier off northeastern Brazil, with evidence of habitat-related age structure.

A total of 221 tiger sharks (Galeocerdo cuvier) ranging from 82 to 426 cm total length (TL) were sampled off northeastern Brazil, including a vertebrally aged subsample of 67 individuals. Growth-band counts ranged from 1 to 15, and agreement between readers was high (percentage error, %E = 2.1%). Marginal increment analysis did not reveal a consistent seasonal pattern in band deposition; therefore, band pairs were treated as annual for growth modelling, with the first postnatal growth-band pair assigned an age of 0.5 years. Back-calculated length-at-age data were used to evaluate alternative growth models. The von Bertalanffy growth model provided the best fit, yielding parameter estimates of L∞ = 401.15 cm TL, k = 0.255 year-1 and t0 = -1.077 years. Predicted TL was 165.1 cm at age 1 year and approximately 200 cm at age 1.5 years, indicating rapid juvenile growth. The age at maturity, inferred from a published maturity length of 310 cm TL, was approximately 4.7 years. Age composition differed significantly between sampling areas, with coastal samples dominated by neonates and very young juveniles, whereas oceanic samples consisted primarily of juveniles, consistent with an ontogenetic shift in habitat use. These findings provide the most comprehensive vertebra-based growth assessment of G. cuvier from northeastern Brazil to date, reinforce previous evidence of rapid early growth in the region and demonstrate how regional context and methodological differences can influence growth estimates for this species.