The biology and behaviour of bay lobsters, Thenus spp. (Decapoda : Scyllaridae), in Northern Queensland, Australia

Abstract

The scyllarid lobster Thenus is captured incidentally to penaeid prawns by otter trawlers fishing the tropical coasts of Australia. Commonly referred to as bay lobsters, they contribute in excess of 800 t (live weight) and over six million dollars annually to Queensland's fishing industry. Two species are now recognised; Thenus orientalis and a second as yet un-described species, referred to as Thenus sp.A. A study was initiated to assess the fishery and to examine biological aspects of each species including; morphology, population structure, reproduction, growth and behaviour. Despite the systematic affinity between Thenus and other lobster genera, several exceptional morphological characteristics were apparent, the most conspicuous of which was the dorso-ventral compression of the body. Specific morphological differences described were subtle. Morphometric analyses confirmed these differences and indicated several significant discontinuities between species and between sexes, in relation to total length, carapace length and weight, pereiopod length, abdominal wwidth and telson length. Significant inter-population differences were also revealed, although they were not consistent for species or sex. Electrophoretic examination of tissue chemistry revealed fixed genetic differences between species. Yield of whole tail weight and tail muscle weight was in excess of 43% and 30% of total body weight respectively. ……………………………