A behavioural rather than resource-focused approach may be needed to ensure sustainability of quota managed abalone fisheries

The Victorian blacklip abalone fishery is Australia's second largest fishery and accounts for about one eighth of reported global abalone catch. Most indicators of stock status for this fishery are favorable, with relatively high daily catch expectations (about 500 kg) among divers. The fishery is subdivided into three management zones, each spanning several hundreds of kilometers of coast, and within each zone divers are restricted to harvesting an equal share of the total allowable catch. During 1998 we initiated an on-board observer program to gain a better understanding of spatial and temporal patterns in catch and effort. Although average CPUE has been increasing, there has also been significant spatial contraction of the fishing grounds away from reefs of low productivity, consistent with the effects of quota introduction during 1988/89 and with subsequent serial depletion. It is this shift away from reefs of low productivity rather than an increase in abalone abundance that is responsible for the trend in CPUE. From our on-board observations, divers do not operate in an area if they believe that they will not meet their daily catch expectations; they have a relatively high catch rate threshold for deciding when to shift to another reef. Catch rates per bag of abalone are several times higher than the daily reported CPUE rates, but vary substantially. We conclude that under quota management, spatial reallocation of effort and incentives to maintain high catch rate thresholds for cessation of fishing at the reef scale in an environment where competition for prime fishing grounds is reduced through restricted entry have been the keys to sustainability of the Victorian fishery during the past 35 years. However, contemporary changes in the fishery, such as reductions in the number of divers who own access entitlements, may lead to unfavourable fishing behaviour patterns among divers. Managers need to be aware that regulations affect diver behaviour and that, despite increased interest in resource manipulation through restoration and sea ranching, it is the diver and not the resource that is managed. Our studies shows that it is important to focus on identifying and promoting behaviour among divers that is desirable in terms of sustainable production within the context of contemporary management strategies.