RASS Records

Plaice in the North Sea and Skagerrak (Subarea 4 and subdivision 3a.20), Demersal otter trawls

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Content Last Updated
14 March 2019

European plaice (Pleuronectes platessa) is a widely distributed bottom-dwelling flatfish that inhabits the temperate waters of the Northeast Atlantic from the White Sea to the Bay of Cadiz most frequently at depths ranging from 0 to 50 m. Adults are usually solitary, burrowing into sandy and muddy habitat, and migrating seasonally between feeding areas and spawning grounds. In this stock most females reach maturity by age 4 and trawl surveys during the spawning period indicate a maximum age of around 10. Spawning occurs in the central and southern North Sea as well as the Eastern English Channel generally between December and March usually at depths ranging from 20 to 40 m. Juveniles in the first two years of life mainly inhabit nursery grounds in estuaries and inshore coastal areas in the southern North Sea before migrating to deeper offshore waters. An offshore shift in the spatial distribution of juvenile plaice has been observed in recent years most likely resulting from higher water temperatures, and juveniles are becoming mature at younger ages and smaller sizes than in the past which may be linked due to fishing activities selectively removing larger individuals and preventing reproduction. Stock size has increased and mortality rates have decreased over the last decade. Plaice feed on worms, molluscs and small crustaceans mainly at night; and they are preyed on by other fish, marine mammals and sea birds.   Landings of plaice in Subarea 4 (North Sea) averaged around 100 000 tonnes per year between 1957 and 2014, and discarding of mostly undersized fish has ranged from 30 to 40% of total international catch weight over the last three years. Plaice are mainly taken by beam trawlers, demersal otter trawlers and demersal seine netters targeting mixed species in the central and southern North Sea. A substantial proportion of plaice caught during the first quarter of the year in the North Sea (50%) consist of spawning migrants from Division 7d (Eastern English Channel). The status of the plaice stock in Subarea 4 has improved over the last decade, with spawning stock biomass increasing since 2007 to a record high and fishing mortality decreasing since 2003 to a record low (ICES, 2017).  


ICES. 2017. Plaice (Pleuronectes platessa) in Subarea 4 (North Sea) and  and subdivision 20 (Skagerrak). ICES Advice on fishing opportunities, catch, and effort. Greater North Sea and Celtic Seas Ecoregions. ICES Advice June 2017

The status of plaice in Subarea 4 (North Sea) and Subdivision 20 (Skagerrak) has been scored a very low risk.  The spawning stock has been at levels consistent with safe and optimal long term yields since 2011 and has been exploited at a rate consistent with maximum sustainable yield since 2009.

This is because spawning stock biomass is above the MSYBtrigger level (the level above which high optimal term yields are expected) and fishing mortality has been close to the FMSY reference point since 2009, which should result in optimal long term yields. 

The management of this stock has been scored a moderate risk. 

The stock is assessed annually by ICES, and control measures appear to have contributed to a healthy increase in stock size over the past decade. However, there is some uncertainty as to the effect of the implementation of the Landings Obligation will have on control and accounting for catches because there is a risk of continued undocumented discarding.

The bycatch risk in this fishery has been scored a high risk. This is because otter trawls have the potential to take relatively high quantities of bycatch (> 40% of catch weight). However, the incoming EU landings obligation is intended to reduce discarding.

There are also catches of demersal elasmobranchs and protected, endangered and threatened (e.g. sharks and rays) species in certain circumstances.   


The habitat risk of this fishery has been scored a high-moderate  risk.  This is because, although otter trawls are considered to have a potential to cause significant habitat damage, damage to vulnerable and sensitive marine habitats is likely to be minimised given that the footprint of the fishery is within core areas, typically historically fished ground.   Spatial management to reduce potential interactions with vulnerable habitats are being developed, as there remains uncertainties about the location of some sensitive seabed habitats so these remain at risk.

TypeCurrent Risk StatusOutlookReason
StockVery LowImproving

The status of the stock is likely to continue to improve in the future given the recent increase in spawning stock biomass to a record high and the decrease in fishing mortality to that assoeciste with Maximum Sustainable Yield.


A multi-annual plan is under development for the mixed demersal fisheries of the North Sea and the precise form this will take is not yet finalised. A new framework for technical measures is also under development. North Sea Plaice is currently subject to the EU landings obligation for a limited number of fisheries, but will come fully under the landing obligation in 2019. All of these developments mean that that is currently some short-term uncertainty around the management of plaice fisheries, but overall management is likely to remain stable.

BycatchHighImprovingBycatch of non-target species in this fishery is relatively high with poor selectivity. However, with technical and spatial management measures continuously under development and the incoming EU landings obligation intended to reduce discarding of managed species, the bycatch risk is likely to reduce in the future.
HabitatModerateImprovingOtter trawls have the potential to affect seabed habitats, but spatial management measures are continuously being developed and will likely reduce the risk. As planned networks of Marine Protected Areas become established, larger areas of sensitive habitat will become protected from trawling.

Nutrition information from 100g raw product

Rich in:
Vitamin B12
Good Source Of:
Vitamin B6
76 (kcal)
1.2 (g)
0.2 (g)
0 (g)
0.37 (g)