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Legal Listing consultation workbook of Cusk
Cusk, Brosme brosme is a slow-moving, sedentary and solitary bottom-dwelling Gadoid fish. It can be distinguished from other cod-related fishes by its single dorsal and anal fins. Cusk can grow to approximately 100 cm in length and 12 kg in weight. They vary in color from reddish brown to green shading to cream to white on the belly.
In Canada, cusk are found primarily in the Gulf of Maine and on the southeastern edge of the Scotian Shelf.
Cusk generally prefer a rocky bottom but are occasionally found over gravel and mud (rarely over sand). They are often caught in deep water (> 200m) and, based on DFO summer survey data, in a temperature range of 6-100 C .
Spawning on the Scotian Shelf occurs from May to August, peaking in June but may be earlier in the Gulf of Maine.
The diet of cusk is difficult to determine because, when brought to the surface, their stomachs are often everted. However, cusk are thought to feed primarily on marine invertebrates (crab, shrimp and krill) and occasionally on fish.
COSEWIC provides the following rationale for designating the cusk as threatened:
The main population of this large, slow-growing, solitary, bottom-living fish resides in the Gulf of Maine/Southeastern Scotian Shelf and has been in decline since 1970. Over three generations, the decline rate is over 90 %, and the fish occurs in fewer and fewer survey trawls over time. Fishing, unrestricted until 1999, is now capped but remains a source of mortality. This species is a monotypic North Atlantic genus.
Threats to Cusk
Current threats to cusk are poorly understood. However, fishing mortality is thought to be the biggest threat facing the recovery of this species. Although there is no directed commercial fishery for cusk, they are known to be taken as bycatch in a number of fisheries including longline fisheries that target other groundfish species such as cod and haddock and trap fisheries.
In 1999, a bycatch cap of 1000 tons was placed on cusk landings in the 4VWX fixed gear fishery. This cap was reduced to 750 tons in 2003.
Since cusk is primarily taken as bycatch in other fisheries, it may be difficult to limit catches of cusk without affecting landings of the target species.
Potential Impacts on Stakeholders
Once added to the List of Wildlife Species at Risk, cusk will be protected. If particular activities are assessed to be a threat to the survival and recovery of a listed species, management measures will be put in place to limit those activities and ensure the protection of species at risk.
These measures may lead to a variety of impacts on stakeholders, including additional costs. The following list is not exhaustive; please use this consultation as an opportunity to list omissions.
Management strategies that could affect aboriginal people fishing for commercial species in areas inhabited by cusk may be considered.
It is important to fully determine the extent of potential threat to cusk by any fishing activities. If a particular fishing activity is identified to be a threat to the survival and recovery of a listed species, management measures will be taken to address the threat. These measures could include increased observer coverage in certain areas, closed areas, gear modifications, or other measures developed in collaboration with industry that willhelp prevent and minimize interactions.
Oil and Gas Industry
The effects of the oil and gas industry on groundfish populations are poorly understood. Seismic testing may have a deleterious effect on demersal fish, eggs and larvae. Proposed oil and gas activities that fall under the Canadian Environmental Assessment Act (CEAA) will need to address the impacts on SARA listed species in accordance with this legislation.
Maritime Forces Atlantic may be asked to prepare guidelines for naval exercises or underwater site remediation in areas of cusk habitat. They may be asked to refrain from undertaking specific types of exercises in these areas or in areas that could impinge on critical habitat (if and when identified). As identified in SARA, these requirements would be waived in emergencies or if national security were affected.
Those wishing to carry out research on cusk or in areas of their habitat may be required to comply with strict guidelines. This may limit the types and/or durations of research permitted on cusk and may lengthen the preparation time required for planning research projects.
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