A proposed management procedure for the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity
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2009
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CCAMLR Science
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Abstract
The status of the toothfish resource in the Prince Edward Islands region is unclear
because CPUE data suggest considerable depletion, whereas catch-at-length information
indicates that past catches have had relatively little impact on abundance. A Management
Procedure (MP) approach is proposed to provide a sound scientific basis to recommend
future TACs in the face of this appreciable uncertainty. Four Operating Models (OMs)
reflecting ‘Optimistic’, ‘Intermediate’, ‘Less Pessimistic’ and a ‘Pessimistic’ current status
for the resource are developed which take account of the different selectivities of past
longline and pot fisheries. These OMs are used for trials of a candidate generic MP which
could provide future TAC recommendations for this resource. The MP uses two data
sources: the recent trend in longline CPUE and the mean length of the catches made. An
MP with control parameter values specified is proposed for implementation based on
the results of the trials. Given the importance of an adequate catch rate for the economic
viability of the fishery, the choice of control parameter values focused primarily on a
reasonable probability of securing a catch rate increase, whatever the current resource
status. MP performance is reasonably robust across a range of sensitivity tests, although
it does deteriorate in conservation terms if the stock-recruitment curve steepness h is low.
These tests also indicate that monitoring of future catch-at-length information would be
necessary to guard against a change in selectivity towards greater catches of older fish.
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Reference:
A, B. & D S, B. 2009. A proposed management procedure for the toothfish (Dissostichus eleginoides) resource in the Prince Edward Islands vicinity. CCAMLR Science. 16(2009):33 - 69. http://hdl.handle.net/11427/19098