Size At Sexual Maturity and the Reproductive Biology of Two Species of Scyllarid Lobster From New South Wales and Victoria, Australia

Abstract

Various aspects of the reproductive biology of the Australian scyllarid lobsters Ibacus peronii and Ibacus sp. were studied for the first time. Sizes at physiological and physical maturity were estimated for males and females of each species and we provide the first documented observations of their reproductive anatomy, mating, oviposition and hatching. Size at physiological maturity was determined via histological examination of ovaries and testes and by identifying the smallest ovigerous females captured in the field. This was estimated (±95% confidence intervals) as 50.4 mm±0.7 mm carapace length (C.L.) for female I. peronii from Coffs Harbour and 50.2 mm± 0.4 mm C.L. for female I. peronii from Lakes Entrance. Male I. peronii and Ibacus sp. were estimated to be physiologically mature when as small as 38.5 mm and 47.4 mm C.L., respectively. All female Ibacus sp. sampled in the study were found to be immature. Size at physical maturity was estimated by examining changes in the relative growth rates of various body parts and, for female I. peronii, was estimated as 54.9 mm±4.0 mm C.L. from Coffs Harbour and 56.6 mm±3.1 mm C.L. from Lakes Entrance. For male I. peronii, size at physical maturity may be approximately 55 mm C.L. The results are discussed in terms of the similarity of these species' reproductive biology with other species of scyllarid and palinurid lobsters, and the consequences of their sizes at sexual maturity for setting a minimum legal size for the fishery of these species.