Terms of Reference

2020 Stock Status Update of British Columbia wild Geoducks

Regional Science Response Process – Pacific Region

March 1, 2021
Virtual meeting

Chairperson: Erin Porszt

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 commercial 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.

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. 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 and stock index estimates are updated annually to incorporate the latest data on population densities, mean Geoduck weights and bed area.

DFO Fisheries Management Branch has requested that Science Branch provide yearly updates of the BC wild Geoduck biomass and stock index estimates. The purpose of this Canadian Science Advisory Secretariat (CSAS) Science Response (SR) is to summarize 2020 updates to BC wild Geoduck biomass and stock index estimates for setting Geoduck quotas for the 2021-2022 fishing season.

Objectives

To provide estimates of BC wild Geoduck stock biomass and stock index, updated in 2020, and summarize the Science Advice provided to fishery managers for setting quotas for the 2021-2022 Geoduck fishing season.

The specific objectives of this review are to:

1. Summarize estimates of Geoduck density, mean weight, and bed area, incorporating the most recent data from fishery-independent density dive surveys (conducted in 2019) and harvest events (2018 fishing season).
2. Provide estimates of Geoduck biomass by Pacific Fishery Management Area and coastwide, for sub-beds in the following categories: open to harvest, below the Limit Reference Point (LRP), impacted by Sea Otter predation, located in closures, and total. 
3. Estimate Geoduck stock status relative to the Limit Reference Point. 
4. Compare TAC set by fishery managers for the 2021-2022 Geoduck fishing season to harvest option estimates.
5. Estimate the actual Geoduck annual harvest rate (TAC divided by biomass) and compare to the Removal Reference.
6. Provide the stock index for the BC Geoduck stock as a whole.

Expected Publication

• Science Response

Expected Participation

• DFO Science
• DFO Resource Management

References

• Bureau, D. 2017. Update to estimation methods for Geoduck (Panopea generosa) stock index. DFO Can. Sci. Advis. Sec. Res. Doc. 2017/070. ix + 55 p.
• Bureau, D., Hand, C.M. and Hajas, W. 2012. Stock assessment framework for the British Columbia Geoduck fishery, 2008. DFO Can. Sci. Advis. Sec. Res. Doc. 2011/121. vii + 79p.
• DFO. 2014. Effects of Geoduck biological sample handling and transport time on mean weight estimation. DFO Can. Sci. Advis. Sec. Sci. Resp. 2014/046.
• DFO. 2017. Update to estimation methods for Geoduck (Panopea generosa) stock index. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2017/037.
• Miller, K.A., Supernault, K.J., Li, S. and Withler, R.E. 2006. Population structure in two marine invertebrate species (Panopea abrupta and Strongylocentrotus franciscanus) targeted for aquaculture and enhancement in British Columbia. J. Shellfish Res. 25: 33-42.