Cj. Walters et R. Bonfil, Multispecies spatial assessment models for the British Columbia groundfishtrawl fishery, CAN J FISH, 56(4), 1999, pp. 601-628
Citations number
25
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
A multispecies spatial model is proposed for evaluation of trawl management
strategies and tested with data from British Columbia groundfish. Minimum
stock sizes are estimated for 16 species using spatial catch per unit effor
t data; these data indicate that only small proportions of most stocks are
exposed to fishing at any time and that exchange rates of fish between the
grounds and other habitats are rapid. A gravity model for spatial effort al
location predicts substantial side effects of marine protected areas or dis
carding of particular species on nontarget species/grounds due to redistrib
ution of fishing effort. Multispecies, multiground delay-difference models
are used in conjunction with the gravity model for spatial effort distribut
ion to predict long-term population responses to various regulatory strateg
ies. This simulation suggests that species composition and spatial structur
e of the fishery are changing slowly due to reduction in abundance of long-
lived species, but rapid collapses of target stocks are unlikely due to spa
tial redistribution of effort in response to local declines. We question wh
ether quota management (individual vessel quotas) can be safely implemented
due to extreme uncertainty about current stock sizes and suggest that a be
tter strategy may be to simply denominate fishing rights as individual effo
rt quotas while providing protection for sensitive stocks through carefully
placed marine protected areas.