Conservation of Recruitment of the Western Rock Lobster (Panulirus cygnus) by Improving Survival and Growth of Undersize Rock Lobsters Captured and Returned by Fishermen to the Sea

Abstract

The western rock lobster (Panulirus cygnus) fishery is one of the largest rock lobster fisheries in the world with an average catch (1974–75 to 1983–84) of 10 million kg. On average, 18 million undersize rock lobsters (sublegal size) are caught, handled, and returned to the sea each season despite the release of many through mandatory escape gaps in traps. Depending on the handling procedure, undersize rock lobsters experience various degrees of exposure, displacement, and damage which adversely affect their survival and growth. Laboratory, field, and tagging experiments showed that handling produced a mortality of 14.6% that costs the industry in excess of $A13 million per season (1984–85 values). An education programme has resulted in improved handling of undersize rock lobsters, and trials have shown that by increasing the size of the escape gap, the number of undersize rock lobsters handled can be reduced by 40–60%. This would result in a significant enhancement of recruitment to the fishery.