Reproductive biology of the greeneye spurdog Squalus chloroculus (Squaliformes, Squalidae)

The reproduction of the greeneye spurdog Squalus chloroculus was studied based on animals caught in the multispecies and multi-gear southern and eastern scalefish and shark fishery on the upper continental slope off southern Australia. One hundred and ninety-nine females (502-990 mm, total length, L_T ) and 189 males (515-810 mm L_T ) were examined. The female reproductive cycle, based on 41 breeding animals, is continuous and triennial, with the pregnancy period estimated to be 31-34 months, seasonal and synchronous with the ovarian cycle; a third of the breeding female population is estimated to give birth between September and December each year. The estimated L_T at which 50% of females are mature is 799 mm (95% c.i.: 794, 804), whereas the L_T at which 50% are maternal is 825 mm (95% c.i.: 817-833), but these estimates are probably biased by the phenomenon of apparent change of L_T at maternity and L_T at maturity following severe length-selective fishing mortality. Litters ranged from four to 15 embryos with a 1:1 sex ratio, and litter size increased with maternal length. The breeding cycle of males is neither seasonal nor synchronous with the female cycle. The estimated L_T of males where 50% are mature was 629 mm (95% c.i.: 603, 645).