Science Response 2015/003
Western Component (4Xopqrs5) Pollock Harvest Control Rule Update Report
Context
Pollock in NAFO Areas 4VWX5 comprise two population components: a slower-growing Eastern Component including Divisions 4V and 4W, as well as Unit Areas 4Xm and 4Xn, and a faster-growing Western Component (WC) including 4Xopqrs and Canadian portions of Area 5. The WC has been the main focus of past analytical assessments, but scientific advice on stock status and catch limits using Virtual Population Analysis (VPA) modeling has been highly variable, especially since the mid-2000s. For example, the 2008 assessment indicated that age 4+ population biomass was at 27,000 metric tonnes (mt) (Stone et al. 2009), while the 2010 assessment update indicated 4+ population biomass was either 23,000 mt or 17,000 mt, depending on whether the very low 2010 Fisheries and Oceans Canada (DFO) Research Vessel (RV) survey indices were excluded or included from the analysis (Stone 2011). Consequently, the Canadian fishing industry recommended exploration of alternative approaches that would provide more stability in future catch limits to allow for better business planning and a more stable fishery.
In 2011, fisheries managers and the fishing industry decided to manage WC Pollock using a risk-management approach and embarked on a Management Strategy Evaluation (MSE) process, with the help of government scientists and outside experts (DFO 2011). MSE is a technique to explicitly consider the uncertainty in stock assessment assumptions and models, and to compare the likely consequences to Management Objectives when a predetermined Management Procedure (MP) incorporating a Harvest Control Rule (HCR) is applied. The Pollock MP was selected on the basis of satisfying three medium-term objectives agreed upon for management of the resource which relate to sustainability, catch levels and the extent of annual catch changes. The MP model was built around an HCR, which either increased or decreased future catch limits based on results from ongoing monitoring from the annual DFO summer RV survey. An Exceptional Circumstances Protocol was put in place to cover situations that fall outside the range for which the MP was simulation tested and, if necessary, to allow for some form of intervention.
Recently, DFO Fisheries and Aquaculture Management posed the following question to DFO Science: What is the Western Component catch level for fishing year (FY) 2015-2016 generated by the Harvest Control Rule described in SAR 2011/054 “Western Component Pollock Management Strategy Evaluation”? This report provides an update to the 2013 report (DFO 2014) on the Western Component Pollock Harvest Control Rule and provides advice on the FY 2015-2016 catch limit generated by the Pollock MP and HCR using updated information from the 2014 summer RV survey. It also describes current status with respect to the provisions in the Exceptional Circumstances Protocol. The HCR with updated monitoring data for 2014 generated a catch limit of 2,781 mt for FY 2015-2016, down 9% from 3,072 mt for FY 2014-2015. The RV survey biomass index decreased from 28.45 kg/tow in 2013 to 8.53 kg/tow in 2014, but this decline did not trigger the exceptional circumstance provision of the RV survey biomass index being < 6 kg/tow for two consecutive years and the Survey Index Ratio being < 0.2.
This Science Response Report results from the Science Response Process of December 4, 2014, on the Western Component Pollock Harvest Control Rule 2014 Stock Status Update.
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