A Preliminary Study to Develop an Abundance Index for Cusk from thier Bycatch in the Gulf of Maine
Cusk (Brosme brosme) is a solitary, sedentary, slow swimming groundfish species that is listed as a Species of Concern in the US, and is currently assessed as threatened and under consideration for addition to Canada’s Species at Risk Act. The cusk fishery in the US is currently not under management, there is little information on cusk life history, the stock structure is unknown, and the biomass is considered to be low. Cusk are found in moderately deep water, on hard bottom substrates, and in relatively cold temperatures on both sides of the North Atlantic. The greatest concentration of cusk is found in the central Gulf of Maine (GOM) extending onto the Western Scotian Shelf. This location of cusk coincides with the Maine lobster trap fishery, and therefore cusk are found as bycatch in lobster traps.
Stock assessment for most groundfish species in the northeast USA depends on the use of fishery-independent abundance index derived from NMFS bottom trawl survey program. However, for species like cusk, because of low catchability and lack of coverage of main habitats by the bottom trawl survey gear, few cusk were caught in the trawl survey program (the Mane DMR only caught 2 cusk over its 11 years of survey duration). Developing an abundance index from cusk bycatch in the lobster fishery becomes a cost-effective way to monitor the dynamics of the cusk stock.