Alternative structural models for the Northeast Chatham Rise orange roughy fishery

Butterworth, Doug S; Brandão, Anabela

Alternative structural models for the Northeast Chatham Rise orange roughy fishery

Working Paper

2006

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

A particular difficulty with assessments of the Orange Roughy resource on the Northeast Chatham Rise is the seeming inability of standard population models, with their standard assumptions of a linear relationship between CPUE and survey indices to abundance, to simultaneously reflect the trends of all these indices. Especially concerning is that while the outputs from these models suggest a recovery in abundance for the Spawning Box after about 1992, the CPUE and hydroacoustic survey results for that period indicate the reverse. A number of mechanisms have been suggested that might be able to resolve these inconsistencies: resident-and-transient fish (related perhaps to spawning migrations), seasonal patterns, hyperdepletion, disturbance, intermittent aggregation, effort saturation and fishing behaviour (Anon. 2005). The purpose of this paper (following a proposal in Anon. 2005) is to investigate this using a simple age-aggregated population model as a basis.

Reference:

Collections

Working Papers

Full item page