The need to answer basic life history questions for White Sharks, Carcharodon carcharias, is well established. However, sampling has been problematic because of the size, mobility, and stock status of this species. In recent years, circulating concentrations of plasma steroid hormones, such as 17-β-estradiol (E2), progesterone (P4), and testosterone (T), have been used to evaluate the events associated with reproductive cycles and sexual maturity in several elasmobranch species. To begin understanding the reproductive cycle of White Sharks, blood samples were collected from four female and five male adult sharks. Circulating levels of plasma E2 ranged from 248 to 1, 826 pg/ml and levels of P4 ranged from 210 to 593 pg/ml in females, and levels of T ranged from 2, 519 to 7, 484 pg/ml in male White Sharks. Additionally, hormone values were assessed in juvenile White Sharks. Circulating levels of T in four juvenile males ranged between 172 and 338 pg/ml, whereas E2 levels in seven juvenile females were all below detectible levels (5 pg/ml). Although the limited sample size precludes any direct interpretation of these results, collectively, the data suggest that these hormones can be quantified and used as noninvasive reproductive endpoints for this species.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Environmental Science(all)