Terms of Reference

Assessment Framework for Scotian Shelf and Southern Grand Banks Atlantic Halibut (Div. 3NOPs4VWX5Zc) - Part 1: Framework

Regional Peer Review Process – Maritimes Region

November 3-6, 2014
Dartmouth, Nova Scotia

Chairperson: 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 completed in 2010 (Trzcinski et al. 2011) 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 2012), during which the 2011 population spawning stock biomass 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.    

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

Objectives

The objective of this meeting is to review the data inputs and indices of abundance for 3NOPS4VWX+5 Atlantic Halibut, as well the model(s) used to determine stock status, reference points, risk analysis and the inter-framework assessment strategy. Specifically,  
Review of Fishery Data Inputs and Indices of Abundance:

• Review fishery data inputs including spatial and temporal distribution, size and age composition.
• Review estimates of natural and fishing mortality from multiyear mark-recapture analysis of tagging.
• Review indices of abundance, including halibut survey fixed station and commercial index catch rates, and all relevant research vessel surveys (Scotian Shelf and Newfoundland).

Assessment of Model(s) to Monitor Stock Status and Productivity:

• Determine the methodology to estimate the current status of the stock, including methods for estimating stock size and fishing mortality.
• Determine the methodology to characterize stock productivity including reference points for fishing mortality and spawning stock biomass.
• Determine forecasting methodology for providing advice on a range of harvest levels associated with various F strategies, including Fref, along with the probability risk of falling below biological reference points over the longer term 15-20 years while limiting annual changes in the TAC to no more than 15%.
• Determine the methodology to estimate the impact on yield of alternative management actions, including:
• Voluntary release of live halibut >125 pounds or 170 cm.
• Determine the minimum legal size that would produce maximum yield:
• Evaluate the impact on yield of moving from the current minimum legal size of 81 cm to a new value (e.g., 83cm or 85cm.)
• Evaluate the impact on yield of moving in a single step or incrementally in [2] cm steps over a short period, (consecutive years or with a one year lag).

Evaluation of Ecosystem Information:

• Describe and review the methodology used to estimate incidental catch of non-target species in the Atlantic halibut fishery.

Establish Annual Review Process and Science Workplan 

• Provide guidance on inter-framework review activities, including the procedure and frequency of providing fisheries management advice and events that would trigger an earlier-than-scheduled assessment.
• Review research program and, based on the assessment needs, develop 5-10 year research priorities.

Expected Publications

• Proceedings
• Research Document(s)

Participation

• Fisheries and Oceans Canada (DFO), Science, Resource Management, Ecosystem Management, and Policy sectors 
• Province of Nova Scotia
• Academics
• Aboriginal communities/organizations
• Fishing Industry  
• Other invited experts  

References

Trzcinski, M.K., S.L. Armsworthy, S. Wilson, R.K. Mohn, and S.E. Campana. 2011. A Framework for the Assessment of the Scotian Shelf and Southern Grand Banks Atlantic Halibut Stock. DFO Can. Sci. Advis. Sec. Res. Doc. 2011/002.
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.