© 2005 International Council for the Exploration of the Sea
Development and evaluation of catch per unit effort indices for southern blue whiting (Micromesistius australis) on the Campbell Island Rise, New Zealand
a National Institute of Water and Atmospheric Research PO Box 893, Nelson, New Zealand
b National Institute of Water and Atmospheric Research PO Box 14-901, Kilbirnie, Wellington, New Zealand
*Correspondence to S. Hanchet: tel: +64 35457739; fax: +64 35481716. e-mail: s.hanchet{at}niwa.co.nz.
This paper develops standardized commercial cpue indices for a highly aggregated spawning fishery in New Zealand waters, and verifies the indices using fishery-independent data. Indices were calculated for all vessels using three different measures of effort, and for vessel subsets based on processing type (surimi and dressed), and relative experience in the fishery. Trends in cpue were consistent with trends in fishery-independent acoustic surveys, age composition of the commercial catch, and recent stock assessment results. In particular, the cpue indices tracked the more than fourfold increase in abundance from 1993 to 1996 associated with the recruitment of the strong 1991 year class, and the decline in relative abundance as this year class was fished down. Despite this being a highly aggregated spawning fishery, there was little evidence for hyperstability. There were also significant differences in fishing strategies of the fleets between periods of high and low fish abundance.
Keywords: fishery-independent, fishing strategies, southern blue whiting, standardized cpue
Received 24 June 2004; accepted 16 February 2005.