Non-lethal methods employed to study the reproductive biology of elasmobranchs

AWRUCH C. A.

Conferencia; Sociedade Brasileira para o Estudo de Elasmobrânquios (SBEEL) VII meeting; 2011

The draughtboard shark Cephaloscyllium laticeps is an oviparous species that inhabits the coastal waters off Southern Australia where it is a common bycatch species in commercial trap, net and hook fisheries. We addressed the reproductive condition of this species based on the level of steroid hormones in the plasma. We tested four hormones, 17â-estradiol (E2), testosterone (T), 11-ketotestosterone (11-KT) and progesterone (P4). 11-KT was not detectable in any shark. T, E2 and P4 were present in females although P4 and E2 were only found in low concentrations in males. Correlations of reproductive development with the level of gonadal steroids were obtained and subsequently used to assess the maturity of sharks caught and released in a scientific reserve. Results from this study demonstrate that assessment of reproductive biology in elasmobranchs can be achieved without harm to the shark. The development of a non-destructive sampling technique has benefits for sampling sharks that do not need to be killed, such as endangered species, species in marine protected areas, nursery areas or bycatch species. This study has significant implications for future elasmobranch research and also advances our knowledge on endocrinology of marine fish.