Research Document - 2016/016
Weight-at-age growth models and forecasts for Northern cod (Gadus morhua)
By Cadigan, N.
Abstract
A Von Bertalanffy growth model is presented to estimate beginning-of-year and mid-year weights-at-age for Northern cod (Gadus morhua) during 1983‑2014 and ages 2‑20. This information is required in stock assessment to estimate beginning-of-year spawning stock biomass and for evaluating fishery biomass landings using mid-year weights. Model parameters are estimated using the Department of Fisheries and Oceans (DFO) autumn Research Vessel (RV) bottom trawl survey mean weights-at-age. The model is applied by cohort but the model is formulated in a mixed-effects framework with fixed parameters for all cohorts and random auto-correlated cohort interactions. This model and time-series structure is also used to provide short-term forecasts, to 2017.
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