THE RISK TO FISHERY PERFORMANCE ASSOCIATED WITH SPATIALLY RESOLVED MANAGEMENT OF ANTARCTIC KRILL (EUPHAUSIA SUPERBA) HARVESTING

The ecosystem approach to fisheries attempts to define objectives for the target species, the wider ecosystem and, critically, the fishery itself. Proposals for implementing this approach often include spatial restrictions on harvesting and it is therefore important to understand how these will affect fishery performance. One metric of potential performance is the probability of encountering exploitable densities of the target species at the scale of fishing operations. The probability of encountering exploitable densities of Antarctic krill, Euphausia superba, at the 1 nm scale during an acoustic survey was predicted by both bathymetry and the mean krill density at the larger scale at which the fishery is managed. This suggests that the risk to fishery performance will increase if management actions relocate the fishery into deeper water. The results also suggest that ecosystem models resolved to the spatial scale of management units could usefully predict effects at the scale of fishing operations. However, correct parameterisation of these models will require better characterisation of threshold densities for efficient exploitation. Finally, the distribution of both catch and fishing effort over an entire fishing season reflected the distribution of krill density observed during the survey.