Trends in productivity of Southern Rock Lobster Jasus edwardsii, across south-eastern Australia: Evidence of a regime shift?

Abstract

In south-eastern Australia, Southern Rock Lobster Jasus edwardsii supports important regional fisheries across the States of South Australia, Victoria and Tasmania. Previous studies across the region have identified considerable synchrony in both larval settlement and recruitment, suggesting that the mechanisms driving these processes occur across broad spatial scales. This study aimed to further examine cross-jurisdictional fishery patterns by analysing long-term trends in Surplus Production (SP) as a measure of annual stock productivity. The results showed evidence of a common trend across south-eastern Australia. Specifically, a substantially rapid decline in SP was observed around the late 1990s and early to mid-2000s period. This decline was particularity evident in both the Northern Zone of South Australia and the Tasmanian fishery. It is suggested that these results may reflect a regime shift in Southern Rock Lobster productivity across south-eastern Australia, which should be considered in terms of future management of the resource.