Stock status update of wild Geoducks in British Columbia for 2023

Abstract

Pacific Geoduck (Panopea generosa) populations occur in discrete beds of soft substrate, distributed throughout the coast of British Columbia (BC). Geoducks are sedentary clams that live buried up to 1 m below the sediment surface. Individual Geoduck beds are connected by means of planktonic larvae, and based on current knowledge, Geoduck populations form a single genetic stock along the BC coast (Miller et al. 2006; Suárez-Moo et al. 2016). 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 portions of the Inside Waters quota areas (Figure 1). 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 2023, there were 2,951 documented Geoduck beds on the BC coast made up of 5,252 sub-beds ranging in size from 0.03 hectares (ha) to 450.44 ha. Some beds are made up of multiple sub-beds, which 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 Oceans 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 Limit Reference Point (LRP) for the BC Geoduck stock is defined as total coastwide current biomass (Bc) being equal to 40% of the total coastwide estimated unfished documented biomass (B’) (Bureau 2017; DFO 2017). The Upper Stock Reference (USR) for the BC Geoduck stock is defined as total coastwide current biomass being equal to 50% of total coastwide estimated unfished documented biomass (DFO 2021a). The stock index is defined as the ratio of total coastwide current biomass to total coastwide unfished biomass (Bc/B’). The LRP and USR are applied on a coastwide basis for the purpose of determining Geoduck stock status (DFO 2021a). DFO Fisheries Management Branch has requested that Science Branch provide yearly updates of the BC wild Geoduck biomass estimates, stock index and stock status, in line with DFO’s Precautionary Approach (DFO 2009). The purpose of this Canadian Science Advisory Secretariat (CSAS) Science Response (SR) is to summarize 2023 updates to BC wild Geoduck biomass estimates provided to fishery managers for setting Geoduck quotas for the 2024-2025 fishing season and to provide updated stock index and stock status. This Science Response Report results from the regional peer review of February 2, 2024 on the Stock Status Update of Wild Geoducks in British Columbia for 2023.