Terms of Reference

Estimates of a Biologically-Based Spawning Goal and Biological Benchmarks for Little Tahltan Chinook (Stikine River Drainage)

Regional Peer Review Process – Pacific Region

November 12-13, 2015
Nanaimo, British Columbia

Chairperson: Bruce Patten

Context

The Little Tahltan River drains an area of approximately 314 km² and flows into the Tahltan River, a major tributary of the Stikine River. The confluence of the Little Tahltan and Tahltan Rivers is approximately 32 km northwest of the community of Telegraph Creek, British Columbia (BC). Little Tahltan Chinook stocks contribute to U.S. approach and in-river fisheries, and in Canada to commercial, First Nation, and sport fisheries.

The Pacific Salmon Treaty (PST) obliges the Parties to use a bilaterally agreed-to, maximum sustainable yield (MSY) based escapement goal for use in managing large Stikine River Chinook salmon (i.e. Chinook salmon greater than 659 mm mid-eye to fork length). A drainage-wide large Chinook salmon spawning goal currently exists; however, there are concerns over a recent decline in the number of Little Tahltan River Chinook, which historically have been a major contributor to the total Stikine production. This concern has generated an interest within the PST process to explore an escapement goal specific to Little Tahltan large Chinook. In Alaska, for an escapement goal to be formally recognized, it needs to be biologically based, to provide sustained yield and be approved by the directors of Commercial Fisheries and Sport Fish divisions. In Canada, advice is sought through a Canadian Science Advisory Secretariat (CSAS) process.

In addition to the above PST obligations, and as part of implementing Strategy 1 of the Wild Salmon Policy (WSP), Fisheries and Oceans Canada (DFO) is required to identify biological benchmarks to assess the status of WSP Conservation Units (CUs) for Pacific Salmon. There are two Chinook Conservation Units (CU) identified for the Stikine River; early and late-run Chinook. Little Tahltan Chinook are considered part of the early-run CU and have served as an abundance index since 1975. Benchmarks have not yet been identified for Stikine River CUs.

DFO Fisheries Management Branch has requested that Science Branch provide advice respecting estimates of WSP biological benchmarks, including a biologically-based spawning goal specifically for Little Tahltan Chinook Salmon as a component of the early-run CU.

This assessment will attempt to estimate the lower WSP benchmark (Sgen) of the abundance metric for the Little Tahltan Chinook. The upper WSP benchmark for abundance is 85% SMSY and follows from the estimate of the spawning goal. Methods utilized to estimate biological benchmarks will be based on the approaches and criteria previously developed and applied for other Pacific Salmon CUs (Holt 2009a, Holt 2009b, Grant 2011).

Results of the assessment, and advice arising from this Regional Peer Review process, will be considered by Canadian and United States management in the development of an integrated management plan for Stikine River Chinook Salmon, and may potentially affect calculations of Total Allowable Catch (TAC) which could change harvest levels of the Parties.  Advice respecting WSP biological benchmarks will contribute to a future assessment of status to meet WSP commitments.

Objectives

The following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below.

Pestal,G.P., Boyce, I., Etherton, P., Richards, P. and Jaecks, T.  Estimates of a Biologically-Based Spawning Goal and Biological Benchmarks for Little Tahltan Chinook (Stikine River Drainage). CSAP Working Paper 2014SAL04

The specific objectives of this review are to:

1. Review Chinook production and escapement data for the Little Tahltan River.
2. Develop biological benchmarks, including the number of spawning adults that would produce a maximum sustainable yield of Chinook Salmon using various models.
3. Examine and identify uncertainties in the data and methods.
4. Examine the models presented in the working paper and provide recommendations on applicability.

Expected Publications

• Science Advisory Report
• Proceedings
• Research Document

Participation

• Fisheries and Oceans Canada (DFO) (Science, Fisheries Management sectors)
• Alaska Department of Fish and Game
• Pacific Salmon Treaty Transboundary Technical Committee Members
• Aboriginal communities/organizations: Tahltan/Iskut First Nation

References

Bernard, D.R., McPherson, S. A., Pahlke, K. A., and Etherton, P. 2000.  Optimal Production of Chinook Salmon from the Stikine River.  Alaska Department of Fish and Game, Fishery Manuscript No. 00-1, Anchorage. iv + 39 p.

Fisheries and Oceans Canada. 2005.  Canada's Policy for Conservation of Wild Pacific Salmon. Fisheries and Oceans Canada, Vancouver, BC. 34 p.

Grant, S.C.H., MacDonald, B.L., Cone, T.E., Holt, C.A., Cass, A., Porszt, E.J., Hume, J.M.B., and Pon, L.B. 2011.  Evaluation of uncertainty in Fraser Sockeye (Oncorhynchus nerka) Wild Salmon Policy status using abundance and trends in abundance metrics. DFO Can. Sci. Advis. Sec. Res. Doc. 2011/087. viii + 183 p.

Holt, C.A. 2009a.  Evaluation of benchmarks for Conservation Units in Canada's Wild Salmon Policy: technical documentation . DFO Can. Sci. Advis. Sec. Res. Doc. 2009/059. xii + 50 pp.

Holt, C.A., Cass, A., Holtby, B., and Riddell, B. 2009b.  Indicators of status and benchmarks for Conservation Units in Canada's Wild Salmon Policy. DFO Can. Sci. Advis. Sec. Res. Doc. 2009/058. vii + 74 p.