Science Response 2019/013

Stock Status Update of Cusk (Brosme brosme ) in NAFO Divisions 4VWX5YZ

Context

Cusk, Brosme brosme, is caught as bycatch in certain directed fisheries. Most landings are in the groundfish longline fisheries. Commercial catch rates for Cusk declined after the 1980s. Changes to management measures (e.g., reductions to trip limits, overall caps, and bycatch percentages) may have contributed to this reduction in catch rates (and landings); however, it is thought the decline in Catch Per Unit Effort (CPUE) is also due to a decline in Cusk abundance (Harris and Hanke 2010). The extent of the decline in abundance is not known.

The Industry-DFO Halibut Fixed Station Longline Survey (Halibut Survey) catch per station has been accepted as the ongoing index for monitoring Cusk biomass. The Upper Stock Reference (USR) and Limit Reference Point (LRP) for Cusk were set at 26.6 kg and 13.3 kg, respectively (Harris et al. 2012). The 3-year geometric mean of the biomass index was accepted as the metric for monitoring Cusk status relative to the USR and LRP.

Cusk was assessed as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2003 and later reassessed as endangered (COSEWIC 2012). In response to the 2003 assessment, the Governor in Council decided in 2013 not to add Cusk to the List of Wildlife Species at Risk set out in Schedule 1 of the Species at Risk Act (SARA) (Minister of Justice, Canada 2013).

Fisheries and Oceans Canada (DFO) Resource Management Sector asked DFO Science to assess the 3-year geometric mean of the Cusk index from the Halibut Survey relative to the USR and the LRP. The information will be used by DFO Resource Management as background for discussions with various industry stakeholders on management measures.

The current 3-year geometric mean (2016-2018) of the Cusk biomass index remains above the LRP at 16.7 kg.

This Science Response Report results from the Science Response Process of December 5, 2018, on the Stock Status Update of Cusk in NAFO Division 4VWX5YZ.

Complete document (PDF, 261 KB)

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