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Canadian Science Advisory Secretariat
Research Document - 2006/061
Reducing Bycatch of Corals and Sponges in British Columbia's Groundfish Trawl Fishery through Trawl Fishery Closures
By Ardron, J.A., and G.S. Jamieson
Abstract
From 1996 to 2002, about 295 tonnes of cold–water corals and sponges were
observed as bycatch in British Columbia’s (BC) groundfish bottom trawl fishery.
Many damaged coral and sponge fragments likely remained on the sea floor,
suggesting that gear impact on species was more extensive than indicated by
bycatch quantity. Recovery from trawl damage is species dependent, and in some
cases may take several decades to centuries. While cold-water structural habitat
remains poorly studied in BC, it is generally accepted that its destruction has
a negative impact on benthic ecosystem dynamics and fished stocks and should be
minimised.
Year-round bottom trawling closures have been established in Australia, the
European Union, New Zealand, Norway, Iceland, Scotland, the USA, and BC, all
with the goal of protecting corals and/or sponges. This paper explores an
efficient spatial establishment of closures in BC to significantly reduce
bycatch and destruction of habitat-forming corals and sponges. Density analyses
of bycatch locations indicates 12 areas of high coral / sponge species
concentration, representing about 7.5% of BC’s continental shelf and slope. Had
these areas been closed, this would have prevented 97% of all coral/sponge
bycatch by weight. The regional diversity of BC’s deep water coral and sponge
species appears to be represented in these twelve areas, though site-specific
verification is required. Economically, these 12 areas are of average economic
value to the fishery. However, because the fishery is an individual quota
fishery, and because of the mobility of many groundfish species, it is difficult
to estimate the potential economic cost of establishing these closures. Closing
an area does not necessarily mean that mobile individuals of targeted species
would not be caught elsewhere, only that they will not be caught in the closed
area. Overall, the proposed potential closure areas contain about one quarter of
historic (1996-2002) trawl sets.
View complete PDF document
(27 pages; 850K)
