Terms of Reference

Canary Rockfish (Sebastes pinniger) stock assessment for British Columbia in 2022

Regional Peer Review – Pacific Region

September 7-8, 2022
Virtual Meeting

Chairperson: Ben Davis

Context

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Canary Rockfish in British Columbia (BC) as “Threatened” in November 2007 due to a population decline^{Footnote 1}. COSEWIC identified fishing as the primary threat to this species. Canary Rockfish are targeted by commercial trawl (~98% of total BC catch, 5‑yr average 2017-2021) and hook and line fisheries. A small amount of catch, often non-directed, is taken in the First Nations fisheries, recreational fisheries and commercial salmon troll fisheries.

The COSEWIC designation led to a Canary Rockfish stock assessment in 2007 (Stanley et al. 2009), followed by a stock assessment update (DFO 2009a). In 2011, a decision was made by the Minister of the Environment to not list Canary Rockfish in Schedule 1 of the Species at Risk Act (SARA), and that Fisheries and Oceans Canada (DFO) would continue to manage this species under the Fisheries Act. In response to the 2007/2009 stock assessments, the trawl total allowable catch was reduced twice but has since been increased to 965 t, which is 81 t below the 2007 level.

The 2007 and 2009 stock assessments depicted a coastwide Canary Rockfish stock that had reached low levels in the mid-2000s but was now increasing slowly. The 2009 update estimated that the population was most likely in the Healthy zone (DFO 2009b); an improvement from the previous assessment which estimated the stock to be in the Cautious zone. The management objective for this species is to keep the population in the Healthy zone.

The bulk of the BC population of Canary Rockfish is found off the west coast of Vancouver Island and in Queen Charlotte Sound (central BC coast), largely in association with the three main gullies – Goose Island, Mitchell’s, and Moresby. There are a few ‘hotspots’ near Langara Spit and in Dixon Entrance (north of Graham Island, Haida Gwaii); however, catch in the northern regions is dwarfed by that from further south. Preliminary analyses in 2021 showed no strong evidence for stock separation along the BC coast based on growth and size frequencies; therefore, the coastwide population will continue to be assessed as one unit.

Data for Canary Rockfish are adequate (in terms of biomass index series and available age structures) to conduct a statistical catch-at-age analysis. In 2007 and 2009, the authors used a model variant of Coleraine called ‘Awatea’. In this proposed assessment, the authors will use the National Oceanic and Atmospheric Administration’s (NOAA’s) Stock Synthesis (SS3) model, which has been adopted by many United States assessment scientists in the Pacific region and was used to assess the Canary population off the lower west coast of the United States (Thorson and Wetzel 2016). This stock assessment software has more flexibility in fitting data and provides some useful diagnostics (e.g., retrospective analysis) that are not available in Awatea. The authors plan to make use of the flexibility afforded by this software platform to explore a wider range of stock hypotheses that could not be run on the previous platform. This includes the capacity to explore the possible impact of environmental effects.

Objectives

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

Paul J. Starr and Rowan Haigh. 2022. Canary Rockfish (Sebastes pinniger) stock assessment for British Columbia in 2022. CSAP Working Paper 2015GRF04

The specific objectives of this science response are to:

1. Recommend reference points consistent with the DFO Precautionary Approach (PA), including the biological considerations and rationale used to make such a determination. If possible, these should include the default DFO limit reference point (LRP) of 0.4B_MSY and the upper stock reference (USR) of 0.8B_MSY, or historical reference points (e.g., B_min). The following additional reference points will be presented: B_MSY, u_MSY, 0.1B₀, 0.2B₀, and 0.4B₀. The choice of reference points is often determined by the complexity of the population model, which, in turn, depends on the quality of the input data.
2. Assess the current status of Canary Rockfish in BC waters relative to the selected reference points. If necessary, provide evidence to support the separation of this species into spatially distinct stocks, and if required, provide advice on the status of these stocks.
3. Using probabilistic decision tables, evaluate the consequences of a range of harvest policies on projected biomass (and exploitation rate) relative to the reference points and provide additional stock metrics.
4. Provide guidance, if needed, to be used by a management rebuilding plan under the DFO PA framework for Canary Rockfish to satisfy recent legislation (Bill C-68). Provide probabilistic decision tables that demonstrate a high probability of the stock growing out of the Critical Zone (i.e., above the LRP) within a reasonable timeframe (1.5-2 generations) if the stock is assessed to be in the Critical Zone.
5. Describe sources of uncertainty related to the model (e.g., model parameter estimates, assumptions regarding catch, productivity, carrying capacity, and population status).
6. Recommend an appropriate interval between formal stock assessments, indicators used to characterize stock status in the intervening years, and/or triggers of an earlier than scheduled assessment (DFO 2016). Provide a rationale if indicators and triggers cannot be identified.
7. Explore environmental effects on the stock assessment with the understanding that their incorporation at this point is exploratory. There is no proven functional system that can be used in population reconstruction and there is very limited ability to interact with black-box platforms like Stock Synthesis. At best, environmental indices might exhibit correlations with population components (e.g., recruitment, growth, natural mortality); however, these correlations can only be explored as sensitivity analyses and should not be used for primary harvest advice.

Expected Publications

• Science Advisory Report
• Proceedings
• Research Document

Expected Participation

• Fisheries and Oceans Canada (DFO) (Science and Fisheries Management)
• Commercial and Recreational Fishing Representatives
• Environmental Non-government Organizations
• First Nations
• Province of BC
• USA Government Agencies (National Oceanic and Atmospheric Administration, Alaska Fish and Game)

References

• DFO. 2009a. Stock assessment update for British Columbia Canary Rockfish. DFO Can. Sci. Advis. Sec. Sci. Resp. 2009/019. 39 p.

  DFO. 2009b. A fishery decision-making framework incorporating the Precautionary Approach.

  DFO. 2016. Guidelines for providing interim-year updates and science advice for multi-year assessments. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2016/020.

  Stanley, R.D., Starr, P. and Olsen, N. 2009. Stock assessment for Canary Rockfish (Sebastes pinniger) in British Columbia waters. DFO Can. Sci. Advis. Sec. Res. Doc. 2009/013. xxii + 198 p.

  Thorson, J.T. and Wetzel, C. 2016. The status of canary rockfish (Sebastes pinniger) in the California Current in 2015. PFMC groundfish stock assessment documents 2016/05. iv + 678 p.