Terms of Reference

Science Advisory Process on Assessment Framework for SW Nova Scotia / Bay of Fundy Herring

Meeting I: 31 Oct. – 1 Nov. 2006
Hache Conference Centre
Biological Station
St. Andrew’s, N.B.

Meeting II: 9-11 January 2007
NAFO Headquarters
2 Morris Drive, Suite 100
Dartmouth, N.S.

Context

The current management plan for the 4VWX herring stock complex pursues three conservation objectives:

1. To maintain the reproductive capacity of herring in each management unit through:
   • persistence of all spawning components in the management unit
   • maintenance of biomass of each spawning component above a minimum threshold
   • maintenance of a broad age composition for each spawning component
   • maintenance of a long spawning period for each spawning component
2. To prevent growth overfishing
   • continue to strive for fishing mortality at or below F0.1
3. To maintain ecosystem integrity/ ecological relationships (“ecosystem balance”)
   • maintain spatial and temporal diversity of spawning
   • maintain herring biomass at moderate to high levels

If during the current review, biological processes become apparent for which additional objectives might be required, these would be proposed to the Scotia-Fundy Herring Advisory Committee for approval.

The 2005 and 2006 assessments of the status of the SW Nova Scotia / Bay of Fundy Management Unit (SWNS/BoF) of the 4VWX stock complex highlighted the need for an in-depth review of the data and models used to assess progress against these objectives. For instance, the population model (VPA) and acoustic surveys estimates of current biomass differ substantially, which has focused attention on whether or not the acoustic survey biomass estimates should be considered absolute or relative as well as the veracity of the VPA.

This review is to be conducted over three sequential meetings scheduled to ensure that modifications identified in a meeting can be incorporated into the preparations and deliberations of the following meeting. The first meeting (31 October – 1 November 2006) will review the stock structure and fishery data inputs. The second meeting (9 – 11 January 2007) will review indices of abundance, including the acoustic survey. The third meeting (26 February – 2 March 2007) will review the models used to determine stock status, productivity, and harvest implications of various management options. The third meeting will also outline the assessment procedure to follow until the next framework review. The framework will be used for the first time in March/April 2007 in support of the 2006/07 fishery.

Throughout the review, recommendations will be made to improve the framework in the longer term. These will be recorded in the proceedings for later discussion and prioritization in a postframework joint DFO – industry herring research program planning meeting, anticipated to occur before 31 May 2007.

Objectives

Definition of the Management Unit and Fishery Data Inputs (31 October – 1 November 2006)

• Review information (e.g. tagging, spawning bed distribution, morphometrics, meristics, growth) on the biological basis of the SWNS/BoF management unit in support of subsequent decisions on the management unit definition by FAM and industry, including
  • Inter-relationships of herring from the SWNS/BoF management unit with herring from the Offshore Scotian Shelf Banks, Coastal (South Shore, Eastern Shore and Cape Breton) and SW NB Migrant Juvenile management units, as well as herring caught in the winter fishery off Cape Cod
• Review precision and bias of current commercial sampling protocols, including
  • Sampling protocol to ensure it is not responsible for the low representation of older fish in the catch at age in recent years
  • Catches and reporting including observer coverage and verification of landing weights
  • Construction of catch at age including protocols for grouping and weighting of samples and catches
• Review estimation procedures of by-catch of other species in the fishery
• Review precision and bias of current aging protocols, including
  • Findings of the 2006 Canada / US Aging Workshop and subsequent otolith exchange
• Review protocols to estimate growth and size at maturity

Review of Indices of Abundance (9 – 11 January 2007)

• Review precision and bias of the industry / DFO Science acoustic survey to evaluate most appropriate use of current data and required changes to utilize these data in alternate ways, including
  • Survey design including survey area, sampling unit (e.g. transect) definition and allocation, and survey sampling timing (both seasonally and on the spawning beds to avoid potential double counting of spawners)
  • Protocols used to estimate post-survey relative indicators of abundance and biomass
  • Influence of spatial and temporal changes in herring distribution and behaviour on the survey results
  • Estimation of survey abundance at age using sampling from the survey
• Document the index of spawning biomass estimated from the historical Bay of Fundy Larval Abundance Survey
• Review the 4VWX summer bottom trawl survey series and explore options including age disaggregated indices
• Consider other sources of abundance indicators that may be available

Review of Models to Assess Status and Productivity (26 February – 2 March 2007)

• For each conservation objective and subobjective, determine biological indicators and the biological consequences of different levels of these (i.e. what does ‘persistence of all spawning components’ mean in real terms?)
• Determine the methodology, exploring a range of models, to estimate the current state of the stock
• Determine the methodology to characterize stock productivity
• Determine the methodology to provide short, medium and long-term yield forecasts
• Provide guidance on the assessment procedure to be used during interim years, recommended timing of subsequent reviews, as well as procedures to verify the on-going efficacy of the framework

Outputs

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

Participation

• DFO Science Maritimes and other regions
• DFO Maritimes FAM
• Scotia – Fundy Herring Advisory Committee
• Provincial representatives
• External reviewers