Terms of Reference

West Coast Vancouver Island Chinook Salmon Escapement Estimation and Stock Aggregation Procedures

Regional Peer Review – Pacific Region

June 18, 19, 20, 2013
Nanaimo, BC

Chairperson: Marilyn Hargreaves
Organizers: Diana Dobson and Stephanie King

Context

As part of the implementation of the Chinook Salmon Annex of the Pacific Salmon Treaty (PST), Canada is required to assess the escapement of West Coast Vancouver Island (WCVI) PST index stocks relative to escapement goals annually.  Canada is also required to assess the abundance for the entire WCVI Chinook Salmon management unit for input into the PST Chinook Salmon management model.  Similar assessments of individual stocks and aggregate stock groupings are required to implement Canada’s Wild Salmon Policy and meet other domestic management needs.

For the assessment of spawning abundance relative to escapement goals, periodic visual surveys are used to estimate escapement of WCVI Chinook Salmon index stocks.  The application of this method has been evaluated and improved through recent studies funded under PST Sentinel Stocks Program.  Similarly, alternative methods have been developed under the Sentinel Stocks Program to estimate aggregate abundance of management units.  As a result of this recent work, a  Canadian Science Advisory Secretariat (CSAS) Regional Peer Review will be held to: i) evaluate the escapement estimation methodology used to evaluate the abundance of WCVI index stocks relative to escapement targets; and, ii) recommend methods for estimating an annual aggregate escapement or appropriate surrogate for the entire management unit.

Objectives

1. To evaluate the visual survey methodology used to estimate WCVI Chinook Salmon escapement for index stocks.

A working paper will be reviewed on day one and will provide the basis for evaluating:

• The method to estimate escapement using periodic visual survey data;
• The quantification of uncertainty;
• The potential for bias in the survey procedure; and,
• Clarity in the descriptions of the survey and sampling protocols.


2. Review and recommend methods suitable for estimating aggregate escapement (or an alternate index of production) for WCVI Chinook Salmon through a workshop approach. 

Presentations on various methods of estimating aggregate salmon escapement will be invited from contributors from other areas and jurisdictions.  To evaluate the methods in the context of the WCVI situation, workshop participants will break-out into small groups representing a range of expertise and backgrounds.  Each group will be asked to report on the following for each method.

• The assumptions and limitations of the method;
• The potential for bias in the method;
• The survey and sampling protocols required to estimate of aggregate escapement;
• The method for estimating uncertainty; and, 
• The performance of the method under various survey conditions, population or habitat characteristics, funding and resource levels.

Plenary sessions will be convened to discuss and recommend the method(s) most appropriate for achieving the objective of estimating aggregate escapement for WCVI Chinook Salmon escapement.  Objective 2 will be addressed during days 2 and 3 of this review process. 

Expected Publications

• CSAS Science Advisory Report (1) providing a summary of the science advice resulting Objectives 1 and 2 of this peer review process.
• CSAS Research Document (1) describing the details of the survey methodology and estimation procedures to be used for estimating WCVI Chinook Salmon escapements.
• CSAS Proceedings summarizing the discussion and recommendations.

Participation

• DFO Science Branch
• Members of the Pacific Salmon Treaty, Chinook Technical Committee (PST) and Sentinel Stock Committee (PST)
• Representatives from the Alaska Department of Fish and Game, Oregon Department of Fish and Wildlife, the Washington Department of Fish and Wildlife, and the National Oceanic and Atmospheric Administration. 
• Representatives from the Nuu-chah-nulth Tribal Council
• Academia