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Assessment of Petrale Sole in British Columbia in 2024

Regional Peer Review - Pacific Region

July 2-3, 2024

Virtual meeting

Chairperson: Steven Schut

Context

Petrale Sole (Eopsetta jordani) is a right-eyed flounder that lives in deep waters along the Eastern Pacific Ocean from California to the Bering Sea, and is caught in the trawl fishery in British Columbia (BC). Petrale Sole was last assessed in 2007 as a single coastwide stock in the combined Areas 3CD5ABCD (west coast Vancouver Island, Queen Charlotte Sound, and Hecate Strait; Starr 2009). Data from the west coast of Haida Gwaii (Area 5E) were not included in the modelled stock at that time due to low catch levels and data. A delay difference model was used for the 2007 stock assessment with data from 1966 to 2006 (Starr 2009); however, given an additional 15 years of data and the development of the groundfish multispecies synoptic trawl surveys, more data-intensive modelling approaches can now be considered (e.g., statistical catch at age models).

Under the Fish Stock Provisions of Canada’s revised Fisheries Act, there is a legal requirement to maintain major fish stocks at levels necessary to promote sustainability, and to develop and implement rebuilding plans for stocks that have declined below their Limit Reference Points. These provisions reinforce previously established Fisheries and Oceans Canada (DFO) policies to manage stocks consistent with the precautionary approach, including DFO’s Fishery Decision-Making Framework Incorporating the Precautionary Approach (DFO PA Policy; DFO 2009). Although Petrale Sole has not been prescribed as a major fish stock under Regulations associated with the Fisheries Act, they may be in the future. Furthermore, characterization of stock status relative to reference points identified in the DFO PA Policy are still required to support fisheries management.

Fisheries and Oceans Canada (DFO) Groundfish Management Unit has requested that Science Branch provide an assessment of Petrale Sole relative to reference points that are consistent with the DFO’s PA Policy, including the implications of various harvest strategies on expected stock status. Given the 15-year time lapse since the last Petrale Sole assessment in BC, a new assessment framework using the Stock Synthesis statistical catch-at-age modelling tool will be developed (Methot et al. 2020).

Objectives

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

Mazur, M.D., Holt, K., and English, P. Assessment of Petrale Sole in British Columbia in 2024. CSAP Draft Research Document. Request ID 213.

The specific objectives of this review are to:

  1. Assess the suitability of a new assessment model framework for Petrale Sole in BC implemented via the Stock Synthesis program (Methot et al. 2020). Various model structures, including age- and size-structured assessment models, and data sets will be considered and reviewed.
  2. Discuss and recommend a limit reference point (LRP), including the biological considerations and rationale used to make such a determination, as well as candidate upper stock reference (USR), candidate removal reference (RR) and candidate target reference points (TRPs) for Petrale Sole in BC. Provide a rationale if the LRP, candidate USR, and candidate RR differ from the PA Policy default reference points (0.4 BMSY, 0.8 BMSY, and FMSY, respectively).
  3. Describe sources of uncertainty related to input data and model assumptions and explore how these uncertainties affect model predictions of productivity, reference points, and trends in biomass and recruitment.
  4. Identify the preferred approach using a base model, or reference set of models to be combined using an ensemble approach, that can be used to characterize stock status for Petrale Sole in BC. Assess the current status of Petrale Sole in BC waters relative to the recommended reference points.
  5. Using probabilistic decision tables, evaluate the consequences of a range of harvest policies on projected biomass (and exploitation rate) relative to the reference points out to 10 years.
  6. If the stock status is estimated to be below the LRP, provide guidance consistent with the development of rebuilding plans under the PA framework for Petrale Sole, to satisfy recent legislation (Fisheries Act).
  7. Examine how environmental conditions and aspects of the species biology may affect the stock as required in the “Guidelines for Implementing the Fish Stocks provisions in the Fisheries Act.
  8. Recommend an appropriate interval between formal stock assessments presented at a regional peer review meeting, 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.

Expected Publications

Expected Participation

References

Notice

Participation to CSAS peer review meetings is by invitation only.

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