Science Response 2020/054

2018 Stock status update of British Columbia wild Geoduck

Context

Pacific Geoduck (Panopea generosa) populations occur in discrete beds of soft substrate, distributed throughout the coast of British Columbia (BC). Geoducks are clams that live buried up to 1m below the sediment surface and are therefore sedentary. Individual Geoduck beds are connected by means of planktonic larvae, thereby forming meta-populations. Based on current knowledge, Geoduck populations form a single genetic stock along the BC coast (Miller et al. 2006).

A dive fishery for Geoducks began in BC in 1976. The fishery is managed with a Total Allowable Catch (TAC), individual vessel quotas, scheduled openings and area quotas. The fishery operates on a three year spatial rotation in the North Coast and Inside Waters regions (Figure 1), while the West Coast of Vancouver Island (WCVI) is fished annually.

Stock assessment and management of the fishery are conducted on the spatial scale of individual Geoduck sub-beds. In 2018, there were 2,888 documented Geoduck beds on the BC coast made up of 5,216 sub-beds ranging in size from 0.03 ha to 451.01 ha. Sub-beds are discrete patches of Geoduck habitat on the sea floor that were initially assigned a common bed code (Bureau 2017). The stock is assessed following methods described in the stock assessment framework (Bureau et al. 2012) which was updated (DFO 2014, Bureau 2017, DFO 2017a) as warranted by new information, analytical approaches, or as requested by Fisheries and Oceans Canada (DFO’s) Fisheries Management branch. Biomass estimates are updated annually with new data on population densities, mean Geoduck weights and bed area.

The Limit Reference Point (LRP) for the BC Geoduck fishery is defined as current biomass (B_c) being equal to 40% of estimated unfished biomass (B’) and is applied on a by-sub-bed basis (Bureau 2017, DFO 2017a). The stock index for a Geoduck sub-bed is defined as the ratio of current biomass to unfished biomass. Updates to unfished biomass and stock index estimation methods presented in Bureau (2017) were first implemented at the time of estimating Geoduck biomass for the 2019-2020 season.

This report provides estimates of BC Geoduck stock biomass and stock index, updated in 2018, and summarizes the Science Advice provided to fishery managers for setting quotas for the 2019-2020 Geoduck fishing season.

This Science Response Report results from the Science Response Process of September 15, 2020 on the 2018 Stock Status Update of British Columbia wild Geoduck.

Science Response 2020/054 (PDF, 1,204 KB)

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