Research Document 2017/026
4X5Y Haddock 2016 Framework Assessment: Modelling and Reference Points
By Wang, Y., Stone, H. H., and Finley, M.
Abstract
The 4X5Y Haddock Framework Assessment: Modeling and Reference Points meeting, held on April 26-27, 2016, was the second of two Maritimes Region of Fisheries and Oceans Canada peer review meetings for 4X5Y Haddock. This meeting was preceded by a 4X5Y Haddock 2014 Framework Assessment: Data inputs and Exploratory Modelling meeting, held on October 22, 2014. This research document summarizes the conclusions from the ‘data inputs’ meeting and describes the methodologies developed for estimating current stock status, fishery reference points, forecasting methodology for providing advice, guidance on inter-framework review activities and events that would trigger an earlier-than-scheduled assessment.
To resolve the retrospective pattern and other model fit issues observed in past 4X5Y Haddock stock assessments, Virtual Population Analysis (VPA) models with random walk in M (natural mortality) for different age groups were explored. A VPA model with M at Ages 10 and older fixed at 0.3, 0.6, and 0.9 for three 5-year time blocks (2000-2004, 2005-2009, and 2010-2014; respectively) was recommended as the new framework model for the 4X5Y Haddock stock assessment. Despite the uncertainties in estimating Fmsy, it was agreed at this framework meeting that an Fref of 0.25 would be a removal fishing mortality reference when the stock is in the Healthy Zone, and an F of 0.15 would be an appropriate target when the stock is in the Cautious Zone. Given that the poor stock recruit relationship precludes the calculation of an appropriate Bmsy, a more conservative Brecover (19,700 metric tonnes (t)) was recommended as Blim for 4X5Y Haddock.
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