Reproductive synchrony of three sympatric species of wobbegong shark (genus Orectolobus) in New South Wales, Australia: reproductive parameter estimates necessary for population modelling

Abstract

Reproductive parameters of three closely-related sympatric species of wobbegong (Orectolobus ornatus, O. maculatus and O. halei) off New South Wales (NSW) were investigated to contribute to a biological basis for the management of a commercial fishery targeting wobbegongs. Estimates of the onset of maturity based on ovary condition were 729 mm, 1117 mm, and 1591 mm total length (TL) for O. ornatus, O. maculatus and O. halei respectively. The length at which 50% of the male population is mature based on clasper calcification was 803 mm, 1282 mm and 1784 mm TL for O. ornatus, O. maculatus and O. halei, respectively, and was similar to female onset of maturity based on uterus condition and to TL-at-maternity. These species of wobbegong had synchronous, triennial reproductive cycles. Follicles took 2 years to enlarge before ovulation. During the first year, follicles remained small, and then grew rapidly during the second year before ovulation during November. Gestation lasted ~10–11 months and parturition occurred during September–October. Mean litter sizes were nine (s.e. 0.5) and 21 (s.e. 1.5) for O. ornatus and O. maculatus, respectively, and increased with female total length in O. ornatus. Pregnant O. ornatus and O. maculatus were frequently caught in northern NSW and no pregnant wobbegongs, or females with large, yolky follicles were captured south of Sydney. Differences in the reproductive conditions of wobbegongs caught in northern and central NSW suggested geographically dependent reproductive behaviour. Knowledge of the reproductive parameters provided in this paper is necessary for adequate fisheries management and species conservation assessments.