Fisheries and Resources Monitoring System

Plaice - North Sea
Marine Resource  Fact Sheet
ICES Advice 2012
Plaice - North Sea
Fact Sheet Citation  
Plaice in Subarea IV (North Sea)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
FAO Names: en - European plaice, fr - Plie d'Europe, es - Solla europea, ru - Камбала морская
Geographic extent of Plaice - North Sea
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2012
Biological State and Trend
State & Trend Descriptors
Exploitation rateBelow targetModerate fishing mortality
Abundance levelAbove targetIntermediate abundance
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Demersal/Benthic.  

Plaice is a bottom dwelling species, mainly feeding on annelids and molluscs. Plaice aggregate at spawning grounds in the first quarter of the year. The condition factor for plaice is highest in summer/autumn on the more dispersed feeding grounds. These feeding grounds are generally located more northerly than the spawning grounds.

Environmental influence on the stock

Juvenile plaice have been distributed more offshore in recent years. This could be linked to environmental changes in the productivity or changes in the temperature of the southern North Sea, but these links have not been shown conclusively. The distribution shift of plaice increased the bycatch of small plaice further offshore.
Geographical Distribution
Jurisdictional distribution: Shared between nations

Water Area Overview
Spatial Scale: Sub-Regional

Ecoregion: North Sea
Geo References
Resource Structure
Considered a single stock: Yes

The fisheries

Plaice is predominantly caught by beam trawlers in the central part of the North Sea with a minimum mesh size of 100–120 mm depending on area. A mixed fishery with sole in the southern North Sea takes place with a minimum mesh size of 80 mm. This mesh size catches plaice under the minimum landing size of 27 cm, which causes high discard rates (in the range of 50% by weight). The discard ratio in the catch has declined in recent years.
Catch distribution Total catch (2011) = 108.523 t, where 63% are landings (60% beam trawl, 36% otter trawl, and 5% other gears), 37% are discards and <1% industrial bycatch.

Effects of the fisheries on the ecosystem

The mixed plaice and sole fishery is dominated by bottom trawls, with bycatch of both commercial and non-commercial species and a physical impact on the seabed. Bottom trawling impacts biomass, production, and species richness. For plaice, the size selectivity may lead to a shift in the age and size at maturation, which means individuals start spawning earlier.
Scientific Advice

ICES advises on the basis of the EU management plan (Council Regulation No. 676/2007) that landings of plaice in Subarea IV in 2013 should be no more than 97 070 t. The implementation of stage two of the plan (as stipulated in article 5 of the EC regulation) is not yet defined.
Overall Assessment Results
Figure Plaice in Subarea IV (North Sea). Summary of stock assessment (weights in ‘000 tonnes). Top right: SSB and F for the time series used in the assessment.
Assessment Model

Scientific basis

Assessment type Age-based analytical assessment (XSA).
Input data Three survey indices (BTS-Tridens, BTS-Isis, SNS).
Discards and bycatch Included in the assessment.
Indicators None.
Other information This stock was benchmarked in 2009 (WKFLAT).
Working group report WGNSSK

Management unit: Yes

Management plans

The EU management plan for North Sea plaice and sole (Council Regulation (EC) No. 676/2007, see Appendix 6.4.7). An evaluation of the plan (ICES, 2010) concluded that the management plan is precautionary.
Source of information

The above excerpts are from the first two pages of the ICES advice, the supporting information to this advice can be read in full at the following reference:
ICES. Plaice in Subarea IV (North Sea). Report of the ICES Advisory Committee, 2012. ICES Advice, WKNSSK 2012. Click to open
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