Science Advisory Report 2011/081

Status update of wild British Columbia geoduck stocks, 2011

Summary

• The area of harvestable geoduck beds in British Columbia (BC) is estimated to be 18,068 ha. The overall mean estimated current density of all surveyed beds is 1.7 geoducks/m² while mean geoduck weight in all beds is estimated to be 1.11 kg.
• Current geoduck biomass, in 2011, in harvestable beds on the BC coast is estimated to be 178,352 metric tonnes (t) (95% confidence bounds: 92,668 t – 339,582 t).
• For all harvestable beds in BC, the sums of the low 95% and low 90% annual harvest options are 1,427 t and 1,590 t, respectively, while the sum of maximum harvest options, according to the management decision rules, is 2,986 t.
• An alternative to the current Limit Reference Point (LRP), based on the proportion of current to virgin biomass, is required due to the uncertainties associated with estimating virgin biomass and because of violations of many of the inherent assumptions of the current LRP. 
• The expansion of sea otter (Enhydra lutris) populations (size and range) in BC will continue to impact the geoduck fishery, leading to further reductions in geoduck populations and harvest options in the future.
• Reallocation of existing geoduck beds to subtidal geoduck aquaculture has resulted in a decrease of 215 ha in bed area available to the wild fishery within the Strait of Georgia. Recent aquaculture tenure applications would impact another 193 ha of bed area within the Strait of Georgia. With increased interest in geoduck subtidal aquaculture, further allocation of wild beds to subtidal geoduck aquaculture will lead to decreased bed area available to the fishery and decreased harvest options.
• More research is planned to investigate the effects of biological sample handling practices on mean weight estimates.

This Science Advisory Report has resulted from a Fisheries and Oceans Canada, Canadian Science Advisory Pacific Regional Advisory Meeting, November 29, 2011 on Status Update of British Columbia Geoduck Stocks, 2011; and Assessment of Inshore Shrimp Stocks along the Coast of British Columbia, 2011. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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