Context The Melbourne skate (Spiniraja whitleyi), a large, Vulnerable skate species endemic to the continental shelf of Australia, is a major bycatch species in the Southern and Eastern Scalefish and Shark Fishery multisector fisheries. Despite its conservation importance, little is known about its reproductive cycle. Aims To describe the reproductive cycle and determine the size at sexual maturity of S. whitleyi in a protected shark refuge area in south-eastern Tasmania using non-lethal techniques. Methods Seasonal plasma concentrations of sex hormones (testosterone, progesterone, 17β-estradiol) were analysed to determine reproductive status. Ultrasonography was used to assess female maturity and determine maximum follicle diameter. Key results Spiniraja whitleyi reaches 50% maturity at 1046 mm for males and 1166 mm for females. Whereas male S. whitleyi appeared to produce sperm year round, with a potential peak in summer, female S. whitleyi exhibited an asynchronous, discontinuous reproductive cycle, with ovulation likely to be occurring in autumn and spring. Conclusions This study showed key reproductive vulnerabilities of S. whitleyi, including a large size at maturity and a discontinuous reproductive cycle, which may limit reproductive output and increase susceptibility to fishing pressure. Implications Reproductive data provide valuable information for developing specific management strategies and conservation efforts for this species.
Woolley et al. (Wed,) studied this question.