Research Document - 2007/010

Re-evaluation of sponge reef complex occurrences and their protection in Pacific Canada

By Jamieson, G.S., K. Conway and J.V. Barrie

Abstract

Evaluation of sponge bycatches in the vicinity of known sponge bioherms in Queen Charlotte Basin indicates that established groundfish trawl closures have reduced trawl impacts. Recent revision of the closure boundaries to better reflect the known spatial distribution of the bioherms will likely even further reduce direct trawl gear impacts. Impacts from other benthic gears could not be assessed because of the lack of relevant bycatch and fishing location data, but all benthic gear activity in the vicinity of all sponge bioherms should be terminated. Although direct incursions of trawls are now being minimized, there is still concern that fishing activity close to the sponge reefs may be impacting the sponges, either accidentally or through increasing suspended solids presence. No direct data on these potential impacts exist, but a precautionary management measure would be to establish larger closures, i.e. bioherm footprints plus a modest buffer zone, around the bioherm complexes. New smaller sponge bioherms have recently been found in both Queen Charlotte Strait and the Strait of Georgia, and it is recommended that effective closures for all benthic fishing gear impacts be also established around these sponge bioherm complexes as well.

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