Report of the Working Group on methods of fish stock assessment (WGMG)

The ICES’ Working Group on Methods of Fish Stock Assessment [WGMG] was established to provide a forum for the development of new methods and the investigation of the properties of fish stock assessment methods. Sound assessment methods are a basic requirement for the provision of sound and credible advice, and the group is regularly tasked by the ICES’ Advisory Committee on Fishery Management [ACFM] to address specific problems identified by ICES’ stock assessment working groups.
This report is the work of a meeting held in Galway, Ireland from 21–26 June 2006 at the Marine Institute under the chairmanship of Carl O’Brien (UK).
The meeting was originally scheduled to end on the 28 June 2006 but was shortened, after consultation with the ICES Secretariat and the Chair of RMC, to allow participants to attend the ICES Symposium on Fisheries Management Strategies, 27–30 June 2006 held in Galway, Ireland. In future, the group suggests that meetings of WGMG should extend for a period of 10-15 days, if possible, in order to ensure adequate time for the development of methods and collaborative working. The shortening of the meeting by two days necessitated changes in the programme of work of the WGMG but the group addressed its original terms of reference (ToRs) by reviewing on-going work within national institutes. In addition to its original ToRs, WGMG was requested by ACFM at its spring 2006 meeting to consider how best to update limit reference points and develop target reference points for use within long-term management strategies. This additional ToR necessitates further work but the group discussed and agreed an approach to the evaluation of long-term management strategies. Three illustrative examples are presented to demonstrate the proposed approach for single species applications.
At its meeting in 2004, WGMG proposed a road map for deriving harvest control rules (HCRs) to aid in the long-term provision of advice and at this meeting in 2006, WGMG further developed the approach using three illustrative case studies – North Sea haddock, northern hake and Irish Sea cod. As a priority, ICES should develop illustrative HCRs for a limited number of priority stocks using the framework proposed in this report as a prerequisite to the development of generic strategies for mixed fisheries management.
The report is organized in Sections. Section 2 describes the overall structure of the report and the ToRs are then addressed within the two main Sections of the report – Section 3 addresses aspects of the sensitivities of stock assessment methods to known data problems and Section 4 addresses issues related to reference points and HCRs. The various working documents and background material presented at the meeting are listed in Section 5; together with their assigned code for ease of reference.
Finally, the group proposes that it should meet in 2007 to continue its work.