Research Document - 2012/026

Reference Points for Cusk (Brosme brosme) in NAFO Divisions 4VWX5Z Under the Precautionary Approach Framework

By L.E. Harris, G. Somers, and D.S. Clark

Abstract

Commercial fishery catch rates for cusk have declined since the 1980s. Management measures may have contributed to the reduction in catch rates; however it is thought the decline in catch per unit effort (CPUE) is also due to a decline in cusk abundance. Presently, there are no surveys dedicated to sampling cusk to estimate abundance or biomass. The commercial CPUE trend data based on landings by longliners catching groundfish were used as an index of biomass for developing reference points under the precautionary approach for cusk in NAFO Divisions 4VWX5Z. The average of the commercial CPUE from the period of higher catch rates (1986-1992) was used as a proxy for Maximum Sustainable Yield (MSY). The LRP and USR were calculated as 40% and 80%, respectively, of this MSY proxy. The commercial CPUE data were scaled to the Halibut Industry survey so that the reference points can be established relative to this on-going series. The proposed USR and LRP are 26.6 kg/1000 hooks and 13..kg/1000 hooks, respectively. The Halibut Industry survey provides an ongoing time series to be used for monitoring stock status. The 3-year mean CPUE from the Halibut Industry Survey is 18.2, which suggests that the stock is in the cautious zone.

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