Terms of Reference

Yellowmouth Rockfish (Sebastes reedi) stock assessment for British Columbia in 2021

Regional Peer Review – Pacific Region

September 8-9, 2021
Virtual meeting

Chairperson: Greg Workman

Context

In 2010, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed the coastal population of Yellowmouth Rockfish (Sebastes reedi) in British Columbia (BC) as ‘Threatened’, based on a decline in abundance and the threat from commercial fishing. As a result, the species was considered for legal listing under the Species at Risk Act (SARA). In a 2011 stock assessment (also acting as a recovery potential assessment), Edwards et al. (2012) modelled the biomass of Yellowmouth Rockfish as 0.614 (0.431, 0.829)^{Footnote 1} of the unfished equilibrium spawning biomass (B₀), and 1.606 (2.685, 4.573) of the spawning biomass at maximum sustainable yield (B_MSY), which is above the upper stock reference for a healthy stock in the Sustainable Fisheries Framework (DFO 2009).

In 2017, a decision was made not to list Yellowmouth Rockfish under Schedule 1 of the SARA. While DFO will continue to manage this species under the Fisheries Act, actions to address conservation concerns were outlined in the order not to list (SI/2017-24 May 3, 2017). In 2019, Bill C-68 was enacted to amend the Fisheries Act, which prompted a review of 57 stocks in BC with the aim to implement sustainable fisheries management plans for the stocks over five years. Bocaccio, Yelloweye Rockfish, and Sablefish were the first groundfish to be assessed in a set of Batch 1 stocks in 2020/21. Yellowmouth Rockfish is slated for Batch 2 assessment in 2021/22.

The bulk of the BC population of Yellowmouth Rockfish is centred in Queen Charlotte Sound (central BC coast), specifically in association with the three main gullies – Goose Island, Mitchell’s, and Moresby. There are also density ‘hotspots’ off the southwest coast of Haida Gwaii (near Cape St. James), off Rennell Sound, off the northwest coast of Haida Gwaii, and off the northwest coast of Vancouver Island. Densities of Yellowmouth Rockfish appear to be low off the west coast of Vancouver Island south of Brooks Peninsula. Preliminary analyses showed no strong evidence for stock separation along the BC coast based on growth and size frequency; therefore, the coastwide population will be assessed, as it was in 2011.

Data for Yellowmouth Rockfish are sufficient (index series and age structures) to conduct a statistical catch-at-age analysis. In 2011, 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. 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 will also provide a bridging analysis comparingtfits to the data using Awatea and SS3 during this transition between modeling platforms.

In the absence of updated science advice, there is uncertainty about the risks posed to the BC Yellowmouth Rockfish stock by current levels of catch. Fisheries and Oceans Canada (DFO) Fisheries Management has requested that DFO Science Branch provide advice regarding the assessment of this stock relative to reference points that are consistent with the DFO’s Fishery Decision-Making Framework Incorporating the Precautionary Approach (DFO 2009), including the implications of various harvest strategies on expected stock status. The advice arising from this Canadian Science Advisory Secretariat (CSAS) Regional Peer Review (RPR) will be used to inform fisheries management decisions to establish catch levels for the species. This work will also inform and supplement decisions external to DFO, specifically COSEWIC.

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. 2021. Yellowmouth Rockfish (Sebastes reedi) stock assessment for British Columbia in 2021. CSAP Working Paper 2019GRF02

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 provisional 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, 0.2B₀, 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 Yellowmouth Rockfish in BC waters relative to the 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. If the data are insufficient to quantitatively evaluate BC Yellowmouth Rockfish in terms of the selected reference points and decision tables, summarise what is known about the status of this species, and discuss the implications for harvest advice.
4. Provide guidance, if needed, to be used by a management rebuilding plan under the DFO PA framework for Yellowmouth 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).
5. Provide probabilistic decision tables to inform a COSEWIC assessment or a subsequent DFO Recovery Potential Assessment. This includes projections up to 3 generations to address COSEWIC’s assessment criteria (indicators A1 and A2) using probability tables of future population status (with respect to the reference criteria) at various catch levels, as well as estimates of the time taken to attain them (with different levels of confidence).
6. Describe sources of uncertainty related to the model (e.g., model parameter estimates, assumptions regarding catch, productivity, carrying capacity, and population status).
7. 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.

The specific objectives of this review are to:

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 & Game)

References

• DFO. 2009. 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.
• Edwards, A.M., Haigh, R. and Starr, P.J. 2012. Stock assessment and recovery potential assessment for Yellowmouth Rockfish (Sebastes reedi) along the Pacific coast of Canada. DFO Can. Sci. Advis. Sec. Res. Doc. 2012/095. iv + 188 p.