Terms of Reference

Evaluation of Available Modelling Frameworks for the Assessment of Southern Gulf of St. Lawrence Winter Flounder (NAFO Division 4T)

Regional Peer Review - Gulf Region

November 16-17, 2023

Moncton, NB

Chairperson: Elizabeth Thompson

Context

The assessment framework meeting will focus on the available data and methodology for estimating the population size and other indicators of the stock status of Winter Flounder (Pseudopleuronectes americanus) in the southern Gulf of St. Lawrence (sGSL, Northwest Atlantic Fisheries Organization (NAFO) Division 4T).

The last full assessment of the Winter Flounder of the sGSL (Surette and Rolland 2019) was completed in March 2017 with advice for the May 2017 to May 2022 fisheries period. An interim update of stock status was also completed in 2019 (DFO 2020) and in 2022 (DFO 2022). This stock did not undergo a full stock assessment in 2021 as was planned in its 5-year assessment cycle since a recovery plan is currently under development.

In anticipation of a new stock assessment and/or rebuilding plan, it is deemed important to update the Winter Flounder population model inputs and assess the modelling framework. This assessment framework meeting will review the data available for the establishment of a new model and examine models of population dynamics of 4T Winter Flounder, in light of increased availability of age estimates.

Objectives

This peer review meeting is to explore whether the availability of new age structure information improves the performance of the Winter Flounder population model, particularly reducing its uncertainty.

The first objective is to examine the available data, and their statistical treatment, which would be used for the population estimation models including catch at age and standardized indices.

The second objective is to evaluate assessment models for the use as the basis for providing science advice on Winter Flounder in the southern Gulf. Specifically, the framework meeting will first provide updated estimates of the stock size (biomass and abundance), recruitment, fishing mortality, and natural mortality of the stock. Overall, this process aims at identifying the modelling framework that can be used to provide stock assessment and rebuilding plan advice.

Expected Publications

• Research Document

Expected Participation

• Fisheries and Oceans Canada (DFO) (Science and Fisheries and Harbour Management)
• External experts

References

• Surette, T., and Rolland, N. 2019. Assessment of the Winter Flounder (Pseudopleuronectes americanus) stock of the southern Gulf of St. Lawrence (NAFO Div. 4T) to 2016 and advice for the May 2017 to May 2022 fisheries. DFO Can. Sci. Advis. Sec. Res. Doc. 2019/026. x + 94 p.
• DFO. 2020. Updated indices of abundance to 2019 for Winter Flounder from NAFO Div. 4T, Witch Flounder from NAFO Divs. 4RST and White Hake from NAFO Div. 4T. DFO Can. Sci. Advis. Sec. Sci. Resp. 2020/008.
• DFO. 2022. Updated index of abundance to 2021 for Winter Flounder from NAFO Div. 4T. DFO Can. Sci. Advis. Sec. Sci. Resp. 2022/025.