Updated investigation of the orange roughy south of Johnies given further data

Brandão, Anabela; Butterworth, Doug S

Updated investigation of the orange roughy south of Johnies given further data

Working Paper

2006

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

The biomass of orange roughy for the region south of Johnies is estimated coarsely by treating the product of standardised CPUE and area as an index of abundance, and then calibrating against population model based estimates of abundance from the recognised aggregations. For the intermittent aggregation model estimates of abundance, for Frankies and Rix, this suggests that cumulative catches from South Johnies would not have appreciably reduced abundance in the region. However, one of two model options to estimate the Johnies abundance yields more pessimistic results, and the decline in the standardised CPUE for the region over the last three years also raises concerns. Results from the ASPM assessment of the Johnies and South Johnies aggregations combined suggest a resource at 48% of its pre-exploitation level. Projections based upon this ASPM suggest that the medium term sustainable yield for the combined aggregation is in the vicinity of 750 t.

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