GLM standardised CPUE abundance indices for orange roughy off Namibia from 1994 now updated to include records up to 2005

Brandão, Anabela; Butterworth, Doug S

GLM standardised CPUE abundance indices for orange roughy off Namibia from 1994 now updated to include records up to 2005

Working Paper

2006

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

GLM analyses are used to standardise the CPUE data for Namibian orange roughy in a manner that deals with tows that record zero catch of orange roughy. The possibility of there being a “learning” period of lower CPUE for a new vessel when it enters the fishery is taken into account. Further, to allow for areal expansion of the fishery at each aggregation, sub-aggregations are defined and CPUE trends estimated separately for each. Different methods for combining the results for the various sub-aggregations to provide a single index for an aggregation are considered. The standardised CPUE values for 2004 (i.e. the July 2004 – June 2005 fishing year) are more often below than above those for the previous year.

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