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Technical Expertise in Stock Assessment (TESA): Maximum Sustainable Yield (MSY) Reference Points and the Precautionary Approach when Productivity Varies

National Workshop, National Capital Region

December 13-15, 2011
Montreal, Quebec

Co-Chairs: Noel Cadigan and Daniel Duplisea


Fisheries and Oceans Canada (DFO) has committed to using a precautionary approach (PA) when managing fisheries. The basis of the PA framework has been outlined in the Sustainable Fisheries Framework released by DFO in April 2009 and described in A fishery decision-making framework incorporating the Precautionary Approach (see The framework identifies three stock status zones: healthy, cautious, and critical, according to upper stock and limit reference points (LRP). The framework also sets the removal rate at which fish may be harvested within each stock status zone, and adjusts the removal rate according to stock status and on pre-agreed decision rules.

An LRP marks the boundary between the cautious and critical zones. When stock size falls below this point, there is a high probability that its productivity is so impaired that serious harm has occurred. An LRP is therefore related to the classic concept of recruitment overfishing and is determined by scientific best practice. However, the productivity of a stock may not be only related to the size of the stock as captured in LRP concepts. For example, the productivity of most cod stocks in eastern Canada decreased in the mid to late 1980s when these stocks were still fairly abundant. Most of these stocks collapsed within 5-6 years of this change. A more detailed understanding of changes in productivity regimes should have implications on setting plausible management goals, LRPs, and removal rates. This is a key component of DFO’s A New Ecosystem Science Framework in Support of Integrated Management (see

At the World Summit on Sustainable Development in 2002 (WSSD), Canada committed to achieving the maintenance or restoration of depleted fish stocks to levels that can produce maximum sustainable yield (MSY). MSY reference points have been adopted by several inter-government fishery organisations (e.g., IWC, ICCAT, IATTC, ICES, NAFO) and other countries (e.g. US, New Zealand). Given this widespread adoption, it is important to consider what are sensible MSY based reference points for the types of variations in productivity (e.g. regimes) that may occur with Canadian stocks. It is also important to consider if, and how, MSY reference points should be incorporated into the PA framework. Stakeholders have criticized some aspects of standard applications of the PA because they do not address changes in stock productivity.

DFO submitted a letter of intent to be an Associated Partner in the European Union Seventh Framework Programme (EU FP7) Beyond MSY proposed project: Beyond Maximum Sustainable Yield (MSY) in fisheries: defining management targets and their consequences (MYFISH). This project will provide definitions of MSY variants, evaluations of the effect and desirability of aiming for these variants and an operational framework for their implementation.

TESA Background

The DFO Technical Expertise in Stock Assessment (TESA) program was created in 2008 to help rebuild capacity in fish stock assessment and to develop technical approaches in a common venue separate from science advisory meetings. The TESA program is composed of three related elements: 1) Stock Assessment Methods Committee (SAMC); 2) annual National Stock Assessment Methods Workshop; 3) Stock Assessment Technical Training/Upgrading program. TESA is led by a Steering Committee composed of the chair (Noel Cadigan), one stock assessment expert from each region, a champion from the National Ecosystem, Oceans and Science Director Committee (NEOSDC) and a Science manager.


TESA is proposing an initial workshop to detail problems with deriving MSY and PA reference points for stocks with varying (i.e. non-stationary) productivity conditions or regimes. A secondary objective is to explore integrating MSY reference points and the PA such that management regimes neither collapse stocks nor forego unnecessary amounts of potential yield. The motivation for the workshop comes from the numerous stocks that are regularly assessed by DFO (e.g. Northern cod) in which data suggests there have been substantial changes in productivity processes.

The aim of the workshop is primarily scoping; to propose research recommendations and possibly solutions. This workshop is the first step in a two step process. Following this initial workshop, TESA proposes to develop and test strategies through a working group to derive MSY and PA reference points for stocks with non-stationary productivity. This may be linked with research on best practices for management strategy evaluations. The results of this working group will be reviewed at a future workshop.

Specific workshop objectives are:

  1. A brief overview of MSY-based PA methods and frameworks around the world
  2. Review working papers of case studies where productivity has varied over time, and what aspects of the PA framework have been addressed.
  3. Review working papers that describe how time-varying productivity conditions (regimes) should influence the calculation of MSY or other PA reference points.
  4. Describe when regime-specific reference points are appropriate, and what are the risks of not considering regime changes.
  5. Contribution to the EU MYFISH project proposal (described above).
  6. The ultimate goal of the study group is to propose MSY options for PA reference points. This could include developing a decision plan to guide DFO when implementing the PA for stocks under changing productivity. This decision plan will be considered at the initial workshop. At a future workshop, the decision plan will be fully developed for establishing PA reference points with specific case studies.
Proposed approach

The participants of the workshop will review approaches used by other agencies/researchers to address PA LRPs and MSY reference points when stock productivity varies. Invited experts will describe their experiences and approaches for dealing with varying productivity when calculating reference points. The workshop will also review case-studies selected from proposals from DFO regions.

Expected Publications

Proceedings Document, and Research Documents if appropriate, will be produced to summarize the workshop discussions and conclusions for computing MSY and PA reference points for the Canadian stocks chosen as case studies whose productivity regimes have changed over time.


Participation will include DFO stock assessment staff (especially those who proposed case studies considered at the workshop), members of TESA, invited experts, and other local university researchers.


Participation to CSAS peer review meetings is by invitation only.

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