Research Document - 2013/089
An update on the biology, population status, distribution, and landings of wolffish (Anarhichus denticulatus, A. minor, and A. lupus) in the Canadian Atlantic and Arctic Oceans
By M.R. Simpson, D. Chabot, K. Hedges, J. Simon, C.M. Miri, and L.G.S. Mello
This paper presents the most recent information on trends in abundance, distribution, and fishery removals of Anarhichus denticulatus (Northern Wolffish), A. minor (Spotted Wolffish), and A. lupus (Atlantic Wolffish) in the Northwest Atlantic and Arctic Oceans; and presents new biological research, in support of a 5-year review of progress made in achieving the objectives of the Recovery Strategy and Management Plan for these species. Previously, all three species were listed on Schedule 1 of Canada’s Species at Risk Act (SARA) as being at risk, due to significant declines in relative abundance indices and reduction in area occupied during the 1980s and early 1990s. Their status was recently (November 2012) upheld by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Signs of population recovery have been detected in some, but not all, regions. For example, indices of relative abundance and distribution for some wolffish species tended to increase in a number of areas surveyed in the Newfoundland and Labrador (NL) Region during the last decade. In recent years, there was a very gradual increase in catch rates of Northern Wolffish during the Fisheries and Oceans Canada (DFO) spring research survey in Div. 3LNO, and during the fall survey in Div. 2J3K and Div. 3LNO. Additionally, in recent years, during the DFO fall research survey in Div. 2J3K and Div. 3LNO, catch rates of Spotted Wolffish were generally increasing. However, during the spring survey, following a general increase in Div. 3LNO over 1995-2006, catches of this species have been declining. In the Maritimes Region, annual mean number per tow for Atlantic Wolffish in the DFO research surveys has declined since 1990, while area of occupancy for this species has exhibited a persistent decline from approximately 60,000 km² in 1975, to about 10,000 km² in 2012.
Due to their status under SARA, mandatory release of Northern Wolffish and Spotted Wolffish is required of fishers operating in Canadian waters. Commercial fishing records of wolffish remain unspeciated, and do not report discards at-sea (except for Canadian Fisheries Observers’ data). Species at Risk Act logbook data from fishers aboard > 35 foot commercial vessels fishing in Canada’s exclusive economic zone (EEZ) indicated that a large percentage of wolffish were released alive in 2005-10, with apparent decreases in the percent alive for Northern Wolffish and Atlantic Wolffish since then.
In the Gulf of St. Lawrence (GSL), dissolved oxygen levels where some wolffish are found were shown to reduce growth rates of Spotted Wolffish in laboratory studies. Further research is required to determine the effects of reduced oxygen on survival, maturation, fertility, egg development, and hatching success of all three wolfish species.
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