Updated stock assessment of Namibian orange roughy populations under the assumption of intermittent aggregation

Abstract

Updated assessments of the four orange roughy aggregations off Namibia, based upon a maximum penalised likelihood approach which uses all available indices of abundance and reflects the proportion of a stock present at the fishing aggregation each year, are presented, and projections under constant catch levels reported. Results suggest that Johnies, Frankies and Rix are all presently at some 60% of their preexploitation level, but that Hotspot is perhaps much more depleted. Overall, medium term sustainable yields would seem to be in the 2 500–2 750 ton range. Broadly speaking, MSY estimates are some 10% less than estimated a year previously. However, varying proportions of abundance present at aggregations from year to year would lead to difficulties in making a catch of this size every year.