Regional Prediction of the Western Rock Lobster, Panulirus Cygnus, Commercial Catch in Western Australia

Abstract

The puerulus settlement at 2 sites on the Western Australian coast has proved to be a reliable predictor of total catch of the western rock lobster fishery, up to 4 years ahead. Over the last 10 years the puerulus settlement has been monitored over a wider area of the fishery enabling regional variation in puerulus settlement to be assessed and allowing regional prediction of catches. Analysis of the three main regions of the fishery (Abrolhos Is., North and South Coastal) indicate that settlement within these regions provides a more accurate predictor of regional catches. This was illustrated in 1991/92, when a higher than expected catch was obtained in the Southern region due to record puerulus settlement at the southern sites in 1988/89. Only average settlement was obtained at the more northern sites, Dongara and Jurien, for 1988/89 and so an average catch was predicted for 1991 /92. The regional analyses have also highlighted the significant effect that the increase in fishing effort in the North Coastal region has had in explaining the variation in the catch, after taking into account the effect of the puerulus settlement. The variation between regions in density-dependent effects between puerulus and recruitment to the fishery is examined.