This report summarizes discussion at the Stock Assessment Workshop and provides staff responses to questions posed. In conjunction with the workshop, an external scientific peer review of the assessment was also conducted.
- Stock Assessment Workshop news release
- Stock Assessment Workshop Final Report (pdf)
- External peer review of stock assessment and IPHC staff response
The links below lead to slides of the presentations.
Morning of June 27, starting at 8:00
Bruce Leaman. Welcome and introductions.
Steve Martell. Objectives of the workshop; ground rules; schedule.
Bruce Leaman. Fishery and management overview. (Commercial vessels and gear. Short history of Commission management: seasons, catch limits, gear restrictions, size limits. Sport and subsistence fisheries. Bycatch fisheries and caps. Present harvest policy: constant harvest rate and proportional harvest. The Commission process. Why the 2006 assessment was kept under wraps until December.)
Heather Gilroy. Commercial fishery removals. (Landings, logbook data, otolith sampling, estimates of legal-sized and sublegal wastage.)
Gregg Williams. Other removals (bycatch, sport catch, personal use).
Bill Clark. Data compilation and preprocessing: hook spacing adjustment, fixed and snap gear; sex decomposition; age misclassification; estimation of size at age; estimation of sampling variances.
Bill Clark. The assessment model: observations, parameters, natural mortality, equations, outputs. Evolution of assessment methods. Detailed discussion of alternative parameterizations of selectivities and catchabilities.
Fitting the model: error structure; log likelihood; penalties; weights. Quality of fits. Retrospective performance. Variances.
Bill Clark. Alternative model fits and model selection.
Steve Martell. Discussion of assessment issues. Selection of alternative fits to be done overnight.
Steve Martell. Discussion of area apportionment issues.
June 28, starting at 8:00
Steven Hare. Stock dynamics and harvest policy. Treatment of bycatch, sport and subsistence catch, and commercial discards of sublegals. Implications of the F35% harvest rate in conjunction with the B30% threshold.
Steve Martell and Bruce Leaman. Summation, reflection, prospection. Possible discussion of alternative review processes.
As part of the ongoing review of the IPHC stock assessment, the Commission contracted with the Center for Independent Experts (CIE) to conduct a peer review of the assessment. The reviewers were Drs. Chris Francis (New Zealand) and Paul Medley (United Kingdom). The terms of reference of the review, the reports of the reviewers, and the IPHC staffs response to them are presented here.
- Statement of Work for External Peer Reviewers
- Report on the 2006 Assessment and Harvest Policy of the International Pacific Halibut Commission by R.I.C.C. Francis
- International Pacific Halibut Commission (IPHC) stock assessment and harvest policy review by Paul A. Medley
- Staff response to the CIE reviewers' reports