Terms of Reference

Workshop to Review Stock Assessment Models for Northern Shrimp

27-28 April 2010

Ramada St. John's
St. John's, Newfoundland

Chairperson: Brian Healey

Context

DFO developed a provisional framework for setting Total Allowable Catch (TAC) for shrimp in Shrimp Fishing Areas (SFA) 0-7 in 2009 which was included as part of the Northern Shrimp Integrated Fisheries Management Plan (IFMP). However, for SFAs 1 and 7, DFO considers this framework a guideline for planning purposes only as the fisheries are subject to NAFO decision making. As mentioned in the IFMP, the provisional framework is to remain in place until it is reviewed and amended. Evaluation of the framework is to take place no later than December 31, 2014.

A nearly identical provisional TAC setting framework had been suggested in 2009 by Industry as a Canadian proposal to NAFO for the shrimp fishery in NAFO Div. 3L. However, in September 2009, it was decided that the domestic provisional framework should be scientifically peer-reviewed before tabling a proposal at NAFO.

Regarding the review of the framework, the IFMP states that “the review of this provisional framework would be enhanced by way of a Management Strategy Evaluation (MSE) process that would include testing and potential re-casting of harvest control rules into mathematical expression, as part of an iterative risk management process including fisheries managers, scientists and industry. Whether or not a full MSE process is engaged, DFO Science will be requested to attempt to calculate FMSY, and evaluate the robustness of the following potential values for SFA 6 TAC-setting “rules” (below), the results of which would inform any process to refine the provisional framework.”

In order to evaluate the current domestic provisional framework and ultimately make recommendations for a proposal to NAFO, several steps will be taken.  SFA 6, having the best dataset of all SFAs, will be used as the test area in the development of a Management Strategy Evaluation (MSE) procedure in consultation with industry.  The final goal of this process, if successful in SFA 6, would the transfer of the MSE procedure to the remaining SFAs of the northern shrimp fishery.  Steps to the final MSE are outlined below:

1. Scientific technical meeting to evaluate two potential quantitative models applied to SFA6 (April 2010).
2. Apply and evaluate the operational model developed in step 1 to the remaining SFAs 1-5 and 7.
3. Complete the development of feedback simulation software and conduct preliminary feedback simulations implementing the operating model, data choices, assessment method, and provisional harvest control rules outlined in the IFMP.
4. Initiate the consultative MSE process with managers and stakeholders reporting initial findings from preliminary feedback simulations by identifying conservation objectives, yield objectives and corresponding performance statistics.
5. Meeting(s) as required with managers and stakeholders to evaluate the performance of candidate management procedures based on the results from the MSE feedback simulations.
6. Final inclusive peer-review of the proposed MSE procedure applied to SFAs 2-6 which could be proposed to NAFO for SFA 7 results and identify management procedures that meet fishery objectives.

Specific objectives of the April meeting (Step 1):

The overall objective will be to complete step 1 of the list outlined above. Specifically:

• Review modeling work undertaken by Quebec Region scientists on the Gulf of St. Lawrence shrimp stock and stock production model applied on the Greenland stocks through NAFO.
• As a test case, evaluate whether the models above can be applied to the SFA 6 shrimp stock as this is the area with most available data in the Newfoundland region.
• Identify key strengths and gaps of each model and select the one appropriate for the northern shrimp SFAs.
• Identify further work required to initiate the MSE process (Step 2).

More specifically participants will address the following questions:

1. To what degree can the model be simplified so a common assessment can be applied to all shrimp stocks of interest?
2. What features of shrimp biology and fishery dynamics are essential in the design of an operating model capable of generating “realistic” recruitment, mortality and fishing processes for shrimp stocks?
3. What features of the model are likely to be well-known with “good” parameter estimates and where are the significant uncertainties?
4. What criteria should be used to judge the suitability of a population model fitting for use as an assessment model for determining next year's TAC versus using it to parameterize an operating model in an MSE context?
5. What is the appropriate balance between fitting an operating model to the available data to get parameter estimates versus inputting these parameter values from other sources, particularly with regard to accounting for observation and process error, including covariances and autocorrelation in the simulations?
6. How can the uncertainty in future shrimp stock productivity be adequately modeled with respect to density dependent vs. environmental (temperature, predation) effects in the operating model?

Working Papers

The following papers will be considered at the workshop:

1. The status of the shrimp resource within SFA 6. (Dave Orr)
2. Management Strategy Evaluation 101 (Peter Shelton)
3. An Assessement Model and Management Stategy Evaluation work for Northern Gulf of St-Lawrence Pandalus borealis (Mathieu Desgagnés)
4. Greenland Stock Production model (Carsten Hvingel)

Outputs and Documentation

The outcomes of the meeting will guide further steps in the development of an MSE procedure for the northern shrimp stocks in SFA0-7.  The MSE procedure will improve the current provisional framework for domestic fisheries and increase consistency through a potential extension of the framework to SFA 7 managed under NAFO.

The results of the meeting are expected to be documented through:

• CSAS Research Documents consisting of the technical reports reviewed during the meeting.
• CSAS Proceedings (to document the discussion of the meeting).

Participation

Given the preliminary, developmental and technical nature of the first three steps, participation will be limited to experts from DFO as well as invited external experts.  Future meetings to address steps 4-6 (of context section) will include broader participation with managers and stakeholders.