Terms of Reference

Assessment Framework for Atlantic Halibut Scotian Shelf and Southern Grand Banks (Div. 3NOPs4VWX+5Zc)

Regional Science Advisory Process – Maritimes Region

Fall 2007 – Winter 2008 – Spring 2009
Dartmouth, NS

Context

A single management area encompassing the Scotian Shelf and southern Grand Banks (3NOPs4VWX+5Zc) has been established for Atlantic Halibut on the basis of tagging experiments conducted during 1958-73 which suggested that Atlantic halibut move extensively throughout most of the Canadian Northwest Atlantic. Halibut caught near the borders of the 3NOPs4VWX+5Zc management unit may belong to other management units (i.e. sub area 4RST) and requires a more precise definition of the boundaries of the 3NOPs4VWX+5Zc halibut management unit.

Prior to 1998, the assessment of the Atlantic halibut resource was hindered by absence of a reliable time series of abundance. The annual Department of Fisheries & Oceans (DFO) summer bottom trawl survey is thought to provide information on incoming recruitment (<81 cm), however, it does not monitor the complete geographic range of the stock and lacks information on the adult (≥ 81 cm) portion of the population. In cooperation with DFO Science, the halibut industry initiated a long line survey in 1998 that catches the full size/age structure over most of the stock area. Since its implementation, halibut stock status has been largely based on this survey’s catch rate trends. While it was concluded that the industry/DFO long line halibut survey has the capacity to monitor the general magnitude and direction of change in halibut population status, by itself, it provides little insight into total abundance or exploitation rate, consequently there is a need for an assessment framework to guide resource management decisions.

In August 2004, members of the Atlantic Halibut Council, the fishing industry, DFO Science, and other agency scientists (other DFO regions and the International Pacific Halibut Commission (IPHC)) convened a two-day workshop at BIO to identify the research requirements of the assessment framework of Atlantic halibut. This framework requires elements additional to the industry/DFO survey time series, for example an assessment model incorporating the survey times series, commercial information, and age-length information. A tag-recapture program providing independent estimates of fishing mortality and abundance can also be incorporated into the assessment framework.

The current review is to establish the assessment framework for Atlantic Halibut. It is to be conducted over three meetings. The first and second meetings (30 – 31 October 2007; 8 – 10 January 2008) will review the management unit, data inputs and indices of abundance, while the third meeting (16 – 17 June 2009) will review the model(s) used to determine stock status.

Objectives

Review of Management Unit, Fishery Data Inputs and Indices of Abundance (30 – 31 October 2007; 8 – 10 January 2008)

• Review information (e.g. tagging, distribution, morphometrics, meristics, growth) on the biological basis of the management unit in support of subsequent decisions on the management unit definition by Fisheries and Aquaculture Management (FAM) and industry, including
  • Interrelations of halibut with populations to the north and south of the management unit
• Review fishery data inputs, including
  • Sampling: Commercial and survey catch, distribution, size and age composition
  • Biology: Growth, age, life history, sex, fecundity, natural mortality, spawning location and timing, recruitment
  • Ecosystem information: Bycatch, trophic information, temperature
• Review indices of abundance, including
  • Fixed station and commercial index
  • All relevant research vessel surveys (southern Gulf northern, Gulf, Newfoundland, and US)

Review of Model(s) to Assess Status and Productivity (16 – 17 June 2009)

• Determine the methodology to estimate the current state 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 harvest levels
• Provide guidance on inter-framework review activities, including
  • Review procedure and frequency of providing fisheries management advice
  • Review events that would trigger an earlier-than-scheduled assessment

Outputs

• CSAS Science Advisory Report outlining the assessment framework
• CSAS Proceedings of the discussion of meetings
• CSAS Research Documents

Participation

• DFO Science, Maritimes and Newfoundland regions
• DFO FAM, Oceans Maritimes, and Newfoundland
• Committee on the Status of Endangered Wildlife in Canada (COSEWIC)
• Aboriginal communities / organizations
• Nova Scotia and New Brunswick Provincial representatives
• Fishing industry
• Non-Government Organizations (NGOs)
• External experts