Science Response 2016/014

Status of Cusk (Brosme brosme) in NAFO Divisions 4VWX5Z Under the Precautionary Approach Framework

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 have declined since 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. 

In 2003, Cusk was assessed asThreatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 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). In November 2012, however, Cusk was reassessed as Endangered by COSEWIC and is subsequently under re-consideration for listing pursuant to SARA.

The Industry-DFO Halibut Fixed Station Longline Survey (Halibut Survey) catch per station has been accepted as a biomass index for Cusk (with the catch at each of 57 stations used in the index standardized to kilograms/1000 hooks).  Reference points have been identified based on the DFO (2009) policy document “A fishery Decision-making Framework Incorporating the Precautionary Approach” (PA Framework). The Upper Stock Reference (USR) and Limit Reference Point (LRP) for Cusk were set at 26.6 kg and 13.3 kg, respectively, in the Halibut Survey (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.

DFO’s Resource Management Sector asked Science to determine the three-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 guidance in discussions with various industry stakeholders on recommendations for management measures.

The current 3-year geometric mean (2013-2015) of the Cusk biomass index remains above the LRP at 19.0 kg., but is within the cautious zone.

The following Science Response Report results from the Science Response Process of December 7, 2015, on the 2015 Stock Status Update for 4VWX5 Cusk.

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