Namibian orange roughy age-structured production model assessments and projections for 2006

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2006

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University of Cape Town

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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 Frankies and Rix are presently at some 60% of their pre-exploitation level, but that Hotspot is perhaps much more depleted at about 10%. Estimates for Johnies range between these extremes, depending on the relative weight accorded survey and CPUE indices of abundance. Overall, medium term sustainable yields would seem to be in the vicinity of 1750 to 2 500 tons. Broadly speaking, MSY estimates are some 5– 30% 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.
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