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Tusk (Brosme brosme)

19.03.2013 // Based on the ICES approach for data-limited stocks, ICES advises that catches should be no more than 9040 t. This is the first year ICES is providing quantitative advice for data-limited stocks.

The last years there has been a reduction in the amount of fishing vessels and this has increased the stock. The Norwegian fisheries in the EU, Faroe and Iceland Economic Zones are regulated by quotas and bilateral agreements.  

Based on historical catch per unit of effort (CPUE) there’s a continuous decline from 1998 to 2004. From 2004 until 2009 there has been an increasing CPUE. The assessment is based on CPUE trends and the harvest is influenced by regulations aimed at other benthic species, e.g. cod and haddock. 

Management and technical regulations of the fishery

For vessels from other countries there’s an annual quota in the Norwegian Zone. While the Norwegian vessels get quotas in other zones negotiated through bilateral agreements.  

The tusk fishery in Norway is regulated through access limitations and by gear and area regulations.  

Ecosystem/Biology

Tusk is considered a benthic species preferring rocky bottom on the continental shelf and on the slope from 100 until 1000 meters. The diet seems to be fish and crustaceans. Tusk has a northerly distribution compared with e.g. ling and blue ling. In the northeast Atlantic, the range extends from southern Ireland to Svalbard and the Kola Peninsula.

Tusk is abundant around Iceland and the Faroe Islands and in the deeper parts of the North Sea and Skagerrak. It is also common in the northwest Atlantic, off Greenland, and along the Reykjanes Ridge.

Spawning is widespread. The age of first maturation is eight to ten yrs, but varies within its geographic range. Maximum age is uncertain, but it can exceed 20 years, maximum length is about 100 cm, maximum weight about 9 kilos. 

It is likely that several populations are found within its wide distribution area, but currently there is insufficient evidence to delineate populations. Very little is known about migrations. The species does not seem to form aggregations, e.g., during spawning or wintertime.  

About the fishery

Tusk has been harvested for centuries over most of its range, often taken as a by-catch species in other directed fisheries.

Tusk is taken in mixed fisheries with ling and as a by-catch in fisheries for cod, mainly in long line and gillnets fisheries but there are also by-catches by other gears, i.e. trawls and hand line.  Tusk is taken in a mixed fisheries with ling and as a bycatch in fisheries for cod, mainly in longline fisheries. The exploitation is influenced by regulations aimed at other groundfish species, e.g. cod and haddock. Catches are primarily by Norwegian vessels and since 2003, EU vessels have been subject to a restricted TAC.

The major fisheries are the Norwegian longline and gillnet fisheries, but there are also bycatches by other gears, i.e. trawls and handline. Other nations catch tusk as a bycatch in trawl fisheries.

Legislation enacted in 2000 to regulate the cod fishery has resulted in a continuous reduction in the number of longliners in the fishery for tusk, ling, and blue ling. By 2011 only 37 vessels above 21 m were in the fishery. 

Total catch (2011) was 11 700 tons, (90% longlines, 9% gillnets, and 1% other gear types.

Map of distribution of tusk

Distribution of tusk in the North Sea

 


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