Research Document - 2011/088
Pre-COSEWIC Review of Atlantic Wolffish (Anarhichas lupus), Northern Wolffish (A. denticulatus), and Spotted Wolffish (A. minor) in the Maritimes Region
By J. Simon, S. Rowe, and A. Cook
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) examined the status of Atlantic wolffish in 2000 and recommended that it be listed as a species of special concern; while in 2001, the status of Northern and Spotted wolffish were recommended to be listed as threatened for the Canadian Atlantic. COSEWIC is required to track the status of wildlife species previously designated as endangered, threatened, and special concern by preparing updated status reports. As part of this process COSEWIC has called for a re-evaluation of the three species of wolffish and DFO, as the department responsible for the management of these species, is required to provide up to date information on the status of these species. This paper examines the DFO research vessel (RV) and industry surveys, extending the analysis to include USA RV surveys and examines observer and commercial landings data within the Maritimes Region. Collectively the data suggest that although Atlantic wolffish is found throughout the Maritimes Region, there are two primary areas of concentration on the Scotian Shelf. On the eastern Scotian Shelf (Divs. 4VW), the abundance of mature individuals has declined by 99% since 1970, while the abundance of immature individuals has increased over the same period. On the western Scotian Shelf (Div. 4X), both immature and mature abundance has declined since 1970. Although these two concentrations exhibit differing trends in abundance, there is no evidence to suggest that they are separate designatable units. On the northeast peak of Georges Bank, there is a small aggregation of Atlantic wolffish that appears to be spatially discrete from the remainder of the surveyed area (Div. 5Z) and that has declined dramatically since 1986. Although there are no directed fisheries for wolffish (assumed to be Atlantic wolffish) in the Maritimes Region, the species is caught as bycatch in other fisheries. Fishers have been known to make directed sets for wolffish within a trip, but they are no longer permitted to direct for the species. Annual landings of wolffish by Canada in Div 5Z have generally been below 100 t since 1963, with recent landings near zero. In Divs. 4X5Y, landings peaked in the late 1970s at 1,600 t and subsequently have declined to less than 100 t in recent years. In Divs. 4VW, landings ranged from 400 to 700 t between 1963 and the early 1980s then declined sharply until 1993 when all directed fishing for cod and haddock ended. Since 1993, wolffish landings have been near zero. An examination of wolffish landings in Div. 4X revealed that wolffish were concentrated on the western peak of Browns Bank, west of German Bank, and in three isolated areas inshore of the 50 fathom line. These inshore areas are not surveyed by the DFO RV surveys and should be examined in more detail as they are potentially areas of critical habitat. The 2001 review of the status of Northern wolffish and Spotted wolffish indicated that both species were near the southern limit of their range in the Maritimes Region. This review confirms that conclusion with the composite distribution pattern from all data sources in the Maritimes Region indicating that both species are restricted primarily to the eastern Scotian Shelf, with some fish found along the shelf edge in Divs. 4WX. Abundance in each survey examined has always been very low with both species occurring in less than 0.5% of the sets.
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