Terms of Reference

Assessment Framework for Scotian Shelf and Southern Grand Banks Atlantic Halibut (Div. 3NOPs4VWX5Zc) - Part 2: Assessment

Regional Peer Review – Maritimes Region

December 8-9, 2014
Dartmouth, Nova Scotia

Chairperson: Dr. Don Bowen

Context

Atlantic halibut (Hippoglossus hippoglossus) is the largest of the flatfishes and ranges widely in the waters off the East Coast. The management unit (3NOPs4VWX5Zc) is based largely on tagging results that indicated Atlantic halibut move extensively throughout the Canadian North Atlantic. The last assessment framework for 3NOPs4VWX5Zc Atlantic halibut was held November 3-6, 2014, using a length-based, age-structured catch-at-length model fitted to the total catch, length compositions in the catch, and to the catch rate and length composition of halibut caught in the trawl and longline surveys. The last assessment of 3NOPs4VWX5Zc Atlantic halibut was conducted in November 2011 (DFO 2011), during which the 2011 population spawning stock biomass (SSB) was projected to be above BMSY (i.e., in the healthy zone). A stock status update was provided in 2014 (DFO 2014), which indicated that the 3NOPs4VWX5Zc Atlantic halibut stock appeared to be increasing despite moderate increases in total allowable catch (TAC).

Under the current multi-year assessment cycle, the 3NOPs4VWX5Zc Atlantic halibut assessment is scheduled every 5 years.

Objectives

The objectives for this science advisory assessment meeting are:

• Review biological and fishery information on 3NOPs4VWX+5 Atlantic Halibut stock. In particular, update the RV survey index of abundance and the halibut survey index of biomass to include 2014.
• Review the assessment model performance, including a retrospective analysis and sensitivity of model to assumptions about M and discarding mortality, and the biomass and recruitment trends.
• Evaluate the current status of the stock relative to the biological reference points (Blim=minimum biomass that produced 50% of the maximum recruitment, Bupper=highest SSB in 1970-2013 time series) developed at the framework meeting held November 3-6, 2014.
• Generate forecasting advice assuming a range of Natural Mortalities (M) including the currently estimated M of 0.15. Estimate probability of falling below biological reference points over 2 generations associated with various harvest strategies, including:
  • Fishing mortality (F)=M, where M=0.1, 0.15, and 0.2, while limiting annual changes in the TAC to no more than 15%
  • Constant TAC
  • Voluntary release of live halibut >125 pounds (167 cm)
  • Minimum legal size 83 cm or 85 cm.
• Report on the bycatch of non-target species in the 3NOPs4VWX+5 Atlantic Halibut fishery and identify any notable changes in the occurrence of these species relative to previous years.

Expected Publications

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

Participation

• Fisheries and Oceans Canada (DFO), Science, Resource Management, Ecosystem Management, and Policy & Economics sectors 
• Province of Nova Scotia and Province of New Brunswick
• International (France and U.S. NOAA)
• Academics
• Aboriginal communities/organizations
• Fishing Industry
• Other invited experts

References

DFO, 2011. Assessment of Atlantic Halibut on the Scotian Shelf and Southern Grand Banks (NAFO Divisions 3NOPs4VWX5Zc). DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2011/001.

DFO, 2014. Stock Status Update of Atlantic Halibut on the Scotian Shelf and Southern Grand Banks (NAFO Divs. 3NOPs4VWX5Zc). DFO Can. Sci. Advis. Sec. Sci. Resp. 2014/016.