Age and growth of tiger shark (Galeocerdo cuvier) from Western Australia

The tiger shark (Galeocerdo cuvier) is believed to be a fast-growing shark that has shown regional variation in growth. Vertebrae samples were taken from 124 tiger sharks (60 females, 38 males, 26 of unknown sex) caught in Western Australia (WA) from 1994 to 1998. Samples were aged using standard vertebral ageing techniques, and the data were used to create length-at-age curves. Dahl-Lee back-calculation was used because of the low number of small juveniles (<140-cm fork length, FL) captured. Males (n = 38) were found to have an age range of 3-21 years and a length range of 145-306 cm FL; females (n = 60) had an age range of 2-31 years and a length range of 118-361 cm FL. A Bayesian multi-model approach to growth-curve fitting was used, and the von Bertalanffy model provided the best fit to back-calculated data on the basis of deviance information criterion (DIC). Parameter estimates for the combined-sex back-calculated data were as follows: asymptotic length (L-infinity) = 372 cm FL; growth-completion coefficient (k) = 0.067 year(-1); and length-at-birth (L-0) = 65.8 cm FL. Growth of WA tiger sharks was slower than that of tiger sharks from most other regions, but similar to that observed on the eastern coast of Australia.