Prawn, Northern, prawns

Pandalus borealis

Method of production — Caught at sea
Capture method — Demersal otter trawl
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea (Skagerrak and Norwegian Deep)
Stock detail — 3.a and 4.a
Picture of Prawn, Northern, prawns

Sustainability rating five info

Sustainability overview

The biomass level is too low for this stock and fishing pressure on it too high. Deep-sea species, e.g. Argentines, roundnose grenadier, rabbitfish and sharks are frequently caught in shrimp trawls in the deeper parts of the Skagerrak and the Norwegian Deep. Sorting grids have been introduced in the Skagerrak to reduce bycatch of non-target fish since February 2013. Grids are compulsorily fitted in nets in all other prawn fisheries in the North Atlantic, including in Norwegian, Canadian and US waters.

Biology

Pandalus borealis, the northern prawn, or cold-water prawn (also known as pink or deepwater shrimp in North America), are crustaceans belonging to the family Pandalidae. The species has a wide distribution throughout the North Atlantic and North Pacific Oceans (the Pacific form is generally regarded as a subspecies, Pandalus borealiseous). The species occurs as far south as the North Sea, Massachusetts, Oregon and Japan. Northern shrimp are hermaphroditic. They develop initially as males, then become female after around 3 years, and complete their lives as females. Life span is around 5 years, although possibly up to 8 years in northern latitudes. They spawn in autumn and females carry the eggs until April/May, when they hatch and the pelagic larvae are released. Total adult length is about 15 cm. This species inhabits areas of soft, muddy sediment with a depth range from 20-1300 m. Prawns migrate vertically at night to feed on zooplankton. Northern prawn are heavily predated on by fish and marine mammals.

Stock information

Criterion score: 1 info

Stock Area

North Sea (Skagerrak and Norwegian Deep)

Stock information

The spawning-stock biomass (SSB) declined after 2010 and has fluctuated at a lower level since then. SSB in 2018 is below MSY Btrigger. Fishing mortality has been above FMSY since 2011, except in 2015 and 2016. Recruitment has been below average since 2008, except for the 2013 year class.

ICES advises that when the MSY approach is applied, catches in 2018 should be no more than 8571 tonnes. Average discard rate of 13.5% in 2012-2014. Discards in 2017 15%.

Management

Criterion score: 0.5 info

No specific management objectives are known to ICES.

Capture Information

Criterion score: 0.5 info

Northern shrimps are mainly caught by 35-45 mm single- and twin-trawl nets (minimum legal mesh size 35 mm). Demersal nets may be towed between 2 boats as in pair-trawling, or one boat may tow more than one net as in twin or multi-rig otter trawling. It is not unknown for some boats to tow up to 8 or 10 nets. A large number of vessels use sorting grids, to reduce bycatch, on a voluntary basis. When sorting grids are not used bycatch species, dominated by saithe and cod, may constitute up to 30% of the landed catch. Deep-sea species, e.g. Argentines, roundnose grenadier, rabbitfish and sharks are frequently caught in shrimp trawls in the deeper parts of the Skagerrak and the Norwegian Deep. Legislation requiring a species-selective grid has been implemented in the Skaggerak since February 2013.

References

ICES 2018. ICES Advice on fishing opportunities, catch, and effort Greater North Sea Ecoregion.Published 26 March 2018 http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/pra.27.3a4a.pdf (Accessed June 2018);
ICES Advice 2015, Book 6 http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2015/2015/pand-sknd.pdf