Studies on the breeding stock of the western rock lobster, Panulirus Cygnus George, were conducted to examine the appropriateness of the current measure of the abundance of the breeding stock.

Research cruises, commercial monitoring and laboratory studies were undertaken between 1984 and 1988. Data from these studies have resulted in a significant improvement in the understanding of the reproductive biology of this species. Size-related repetitive breeding is now known to be an important feature of reproductive activity in P. cygnus. Additionally, an improved, curvilinear fecundity-carapace length relationship now replaces the linear one reported in the early 1070’s. The interpretation of research log book data has also been enhanced.

The current spawning stock index was reviewed and found to be unrepresentative of the stock as a whole. The basis for the development of a new index (or indices) has been provided by the study.