Terms of Reference

Scientific Evidence to Inform Spawning Practices at Fisheries and Oceans Canada Salmon Hatcheries in the Pacific Region

Regional Peer Review - Pacific Region

March 5, 2024

Virtual Meeting

Chairperson: Geoff Lowe

Context

Supplementation of Pacific salmon populations through hatchery enhancement creates potential risks to the genetic integrity, genetic diversity and fitness of wild salmon, which are defined as salmon that have spent their entire lives in the wild and are the offspring of naturally-spawned parents (DFO 2005). These risks are mitigated and minimized through genetic management of hatchery broodstocks. The Fisheries and Oceans Canada (DFO) Salmonid Enhancement Program (SEP) currently uses guidelines developed in the 1980s to direct broodstock collection and spawning within their enhancement lines (DFO 2016). In recent years there have been substantial advances in scientific knowledge regarding the effects of hatcheries on wild salmon. A review of the genetic management of broodstock guidelines is timely to ensure operating are consistent with current science advice.

A recent Canadian Science Advisory Secretariat (CSAS) research document, Genetically Based Targets for Enhanced Contributions to Canadian Pacific Chinook Salmon Populations (Withler et al. 2018), established “proportionate natural influence” (PNI) designations for Canadian salmon populations to facilitate management of genetic risks associated with hatchery selection and domestication. The application of these designations is currently being developed for the SEP’s enhancement lines, which have objectives spanning harvest, assessment, rebuilding, conservation and education/stewardship. Therefore, it is also essential to evaluate if the general broodstock collection and spawning guidelines require modifications depending on the particular management objective or PNI designation of a SEP enhancement line.

DFO SEP has requested science advice on updates to the broodstock collection and spawning practices at SEP operated and supported hatcheries in the Pacific Region. This assessment and advice arising from this Canadian Science Advisory Secretariat (CSAS) Science Response (SR) process will be used to update both the SEP genetic management guidelines (DFO 2016) and the SEP risk management framework for enhancing Pacific salmon (DFO 2013).

Objectives

The specific objectives of this review are to:

1. Assess the potential genetic impacts of existing hatchery broodstock collection guidelines regarding the proportion of the escapement removed for broodstock, and the relative use of natural- versus hatchery-origin spawners compared to their representation in the escapement.
2. Examine published scientific knowledge to provide advice on best practices for maintaining genetic diversity in hatchery broodstock depending on broodstock size and enhancement objectives, particularly with reference to the use of males, cryopreserved milt, sex ratios and matrix spawning.
3. Evaluate the potential consequences of random versus intentional selection of hatchery spawners based on fitness-related traits (e.g., size, age or run timing) with dedicated consideration of the use of jack males in hatchery broodstocks.

Expected Publication

• Science Response

Expected Participation

• Fisheries and Oceans Canada (DFO) (Salmonid Enhancement Program, Science Branch, Stock Assessment)
• Committee on the Status of Endangered Wildlife in Canada
• Taplow Ventures Ltd.

References

• DFO. 2005. Canada’s Policy for Conservation of Wild Pacific Salmon. Vancouver, BC. 49 p.
• DFO. 2013. A Biological Risk Management Framework for Enhancing Salmon in the Pacific Region. Salmonid Enhancement Program, Fisheries and Oceans Canada, Pacific Region.
• DFO. 2016. A Compilation of Operational and Planning Guidelines for the Salmonid Enhancement Program. Salmonid Enhancement Program. Fisheries and Oceans Canada, Pacific Region.
• Withler, R.E., Bradford, M.J., Willis, D.M., and Holt, C. 2018. Genetically Based Targets for Enhanced Contributions to Canadian Pacific Chinook Salmon Populations. DFO Can. Sci. Advis. Sec. Res. Doc. 2018/019. xii + 88 p.