Science Response 2021/035

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, live buried up to 1 m 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 commercial dive fishery for wild Geoducks began in BC in 1976. The BC Geoduck 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 quota areas (Figure 1), while the West Coast of Vancouver Island (WCVI) area is fished annually.

Stock assessment and management of the fishery are conducted on the spatial scale of individual Geoduck sub-beds. In 2020, there were 2,915 documented Geoduck beds on the BC coast made up of 5,232 sub-beds ranging in size from 0.03 hectares (ha) to 450.44 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). The framework was updated (DFO 2014, Bureau 2017, DFO 2017) as requested by Fisheries and Ocean’s Canada’s (DFO’s) Fisheries Management branch. Biomass estimates are updated annually with new data on population densities, mean Geoduck weights and bed areas.

The provisional Limit Reference Point (LRP) for the BC Geoduck stock is defined as current biomass (B_c) being equal to 40% of the estimated unfished documented biomass (B’) (Bureau 2017, DFO 2017). The stock index is defined as the ratio of total coastwide current biomass to total coastwide unfished biomass (B_c/B’). It is recommended that the LRP be applied on a coastwide basis for the purpose of determining Geoduck stock status. It is recommended that a provisional Upper Stock Reference (USR), defined as total coastwide current biomass being equal to 50% of total coastwide estimated unfished documented biomass, be applied to the Geoduck stock.

This report provides estimates of BC Geoduck stock biomass and stock index, updated in 2020, and summarizes the Science Advice provided to fishery managers for setting quotas for the 2021-2022 Geoduck fishing season.

This Science Response Report results from the Regional Science Response Process of March 1, 2021 on the 2020 Stock Status update of British Columbia wild Geoducks.

Science Response 2021/035 (PDF, 777 KB)

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