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

Brandão, Anabela; Butterworth, Doug S

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

Working Paper

2004

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

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.

Reference:

Collections

Working Papers

Full item page