Terms of Reference

Framework Review for Atlantic Halibut on the Scotian Shelf and Southern Grand Banks in NAFO Divisions 3NOPs4VWX5Zc: Part 1 - Review of Data Inputs

Regional Advisory Process – Maritimes Region

November 23 – 26, 2021
Virtual meeting

Chairperson: Michelle Greenlaw

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 sized 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.

This meeting will be the first of a two-part assessment framework review to review data inputs and development of new modelling approaches.

Objectives

This meeting will review fishery data inputs, biological information, and ecosystem impacts of the fishery and survey indices of abundance, and prepare data inputs for the assessment model:

• Consider the ecosystems where the assessed stock occurs, including relevant summaries of oceanographic conditions, biological community structure and trends, and pertinent knowledge of ecological interactions (e.g. predator, prey) and stressors (e.g. anthropogenic impacts).
• Review indices of abundance and size and sex composition from the longline Halibut survey (stratified random and fixed station, and commercial index) and all relevant DFO research vessel surveys (Scotian Shelf and Newfoundland).
• Review fishery data inputs including spatial and temporal distribution and size composition.
• Update the growth model for Halibut, including testing of differences in growth rate across the stock area.
• Review estimates of natural and fishing mortality from the multiyear mark-recapture analysis.
• Review the indices produced by the longline Halibut stratified random survey and hook occupancy model.
• Review ecosystem impacts of the fishery: describe and review the methodology used to estimate incidental catch of non-target species and identify any notable changes in the occurrence of these species relative to previous years
• Prepare data inputs and present an update to the Statistical Catch at Length (SCAL) stock assessment model (Cox et al. 2016).

Expected Publications

• Proceedings
• Research Document(s)

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.