Terms of Reference

Framework Review for Atlantic Halibut on the Scotian Shelf and Southern Grand Banks in NAFO Divisions 3NOPs4VWX5Zc: Part 2 - Review of Modelling Approaches

Regional Advisory Meeting – Maritimes Region

March 1–4, 2022
Virtual Meeting

Chairperson: Tara McIntyre

Context

The Atlantic Halibut (Hippoglossus hippoglossus) is the largest of the flatfishes and ranges widely over Canada’s East Coast. The management unit definition (3NOPs4VWX5Zc) is based largely on tagging results that indicate that Atlantic Halibut move extensively throughout the Canadian North Atlantic with smaller fish moving further than larger fish. The Atlantic Halibut fishery was unregulated until a total allowable catch (TAC) was implemented in 1988 and a legal size limit (≤ 81 cm total length) was set in 1994. While the Fisheries and Oceans Canada (DFO) research vessel (RV) survey provides a useful index of abundance for incoming recruitment, it does not provide an index of exploitable biomass (≤ 81 cm total length) since larger fish are captured infrequently. An industry-DFO longline Halibut Survey on the Scotian Shelf and southern Grand Banks (3NOPs4VWX5Zc) was initiated in 1998 to better estimate adult biomass. A commercial index is conducted in conjunction with the longline Halibut Survey. The longline Halibut Survey provides an index for exploitable biomass of Halibut from the Scotian Shelf and southern Grand Banks. The commercial index provides data on the population size structure. A tagging study was initiated in 2006, wherein both recruits and commercial size325d fish were tagged and released. Recoveries are used to estimate exploitation rate.

A new assessment model and assessment procedures were peer-reviewed in November 2014, to inform Fisheries Management (FM) of the status of the Halibut resource and to provide harvest level advice based on standardized catch rates from the industry-DFO Halibut Survey and stratified mean numbers per tow from the RV survey. Science advice has since been provided through annual updates and evaluation of abundance indicators, landings, and estimates of fishing mortality from tagging data.

In November of 2021, the first peer review meeting of a two-part assessment framework review took place for review of the data inputs. This meeting is the second peer review meeting of the assessment framework review and will focus on a review of the modelling approaches and science advice on harvest strategies.

Objectives

• Incorporate suggestions from previous framework meeting into the spatially integrated statistical catch-at-length (SISCAL) model, including new growth parameters and adding NL survey and observer data.
• Use SISCAL model to estimate the current status of the stock, including total biomass and fishing mortality.
• Present analysis of hook competition in the stratified random survey.
• Determine methodology and characterize stock productivity including reference points for fishing mortality and spawning stock biomass (LRP, USR, removal reference).
• Incorporate, where possible, environmental conditions in the stock assessment.
• Determine forecasting methodology for providing advice on a range of harvest levels associated with various harvest strategies. Evaluate performance of Management Procedures, against approved Management Objectives.
• Provide catch advice for each of the Management Procedures that meet the approved Management Objectives.
• Consider fixed survey and stratified random survey as indices of abundance for the HCR and how to transition to random survey.
• Evaluate the impact on yield of moving from the current minimum legal size of 81 cm to a new value.
• Evaluate voluntary release of large live Halibut.
• Provide guidance on inter-framework review activities, including the procedure and frequency of providing fisheries management advice on stock status and harvest advice, as well as identifying events that would trigger an earlier-than-scheduled assessment.

Expected Publications

• Proceedings
• Research Document(s)
• Science Advisory Report

Expected Participation

• DFO Science
• DFO Resource Management
• Indigenous Communities/Organizations
• Industry stakeholders
• Provincial representative
• Non-government organizations
• Other invited experts
• French Research Institute for Exploitation of the Sea (IFREMER)

References

• Cox, S.P., Benson, A., and den Heyer, C.E. 2016. Framework for the Assessment of Atlantic Halibut Stocks on the Scotian Shelf and Southern Grand Banks. DFO Can. Sci. Advis. Sec. Res. Doc. 2016/001.