Plaice

Pleuronectes platessa

Method of production — Caught at sea
Capture method — Beam trawl
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea, Skagerrak
Stock detail — 4, 3a.20
Picture of Plaice

Sustainability rating two info

Sustainability overview

Updated: July 2019.

The plaice stock in the North Sea and the Skagerrak is not overfished and not subject to overfishing. However, discards are very high and should be reduced. Both beam and otter trawls can take high levels of bycatch and cause damage to the seabed. Beam trawling has higher bycatch rates, including some shark and ray species.

Several MSC-certified plaice fisheries operate in the North Sea.

Biology

Plaice is a bottom-dwelling flatfish. It spawns in the early months of the year (January to March) and sometimes makes long spawning migrations. North Sea plaice reach between 35 and 45 cm in their 6th year. It is a long-lived species, becoming sexually mature at 3-7 years (females) 2-6 (males) and living 30 years or more. Maximum reported age 50 years.

Stock information

Criterion score: 0 info

Stock Area

North Sea, Skagerrak

Stock information

The stock is in a very good state, and fishing pressure is at sustainable levels.

From 1957 to 2007, the spawning-stock biomass (SSB) was below sustainable levels (MSY BTrigger, 564,599 tonnes). However, it has markedly increased since then, reaching 967,508t in 2018 - well above sustainable limits. This follows a substantial reduction in fishing mortality (F) since 1999. Fishing mortality reached sustainable levels (i.e. below FMSY, 0.21) for the first time in 2009, and has stayed just below this limit ever since, being at 0.187 in 2018. Recruitment has been fluctuating around the long-term average since the mid-1990s. There is some uncertainty in assessing the abundance of older fish (10+), and therefore some uncertainty in the estimates of SSB.

ICES advises that when the MSY approach is applied, catches in 2020 should be no more than 131 439 tonnes. This is a 7.6% decrease from the year before owing to recruitment fluctuations. Recent Total Allowable Catches (TACs) have been in line with scientific advice, and catches have been in line with TACs.

Survey data implies that older fish are likely migrating to the north-western part of the North Sea, where the targeted fishing effort is low, and this has partly resulted in reduced fishing mortality at older ages, and an upward trend of SSB in recent years (in 2018, plaice aged five and older contributed to 85% of the SSB). Plaice in the Skagerrak (area 3a.20) is considered to have an Eastern and a Western component, with the Western component missing with plaice migrating in from the North Sea. Most of the catches are on summer feeding aggregations in the Western Skagerrak. North Sea plaice also migrates into the eastern English Channel (area 7d) during January-March, so 50% of the mature animals from that area during Q1 are included in the North Sea plaice assessment.

It is possible that the high population of plaice could have other ecosystem impacts, for example the ability of benthic prey populations to support such a high plaice population. This, and warming North Sea waters, could be the causes of slower growth rates seen in the stock recently.

Management

Criterion score: 0.25 info

The 2007 recovery plan successfully brought fishing pressure down to sustainable levels, and the stock has since dramatically increased in size. However, discards are high, at 50%, and landings of small fish are below what monitoring programmes suggest they should be, indicating better monitoring and enforcement of the Landings Obligation might be needed.

This stock is covered by the EU’s North Sea Multi Annual management Plan (MAP), and although the MAP has not been adopted by Norway, joint TACs are agreed through the EU-Norway Agreement. Total Allowable Catches (TACs) currently follow ICES’ MSY-based approach and are at sustainable levels.

Since 2016, large mesh trawlers have been under the landing obligation in the North Sea. In 2019 the fleets that contribute most to the total discards will also fall under landing obligation in the North Sea, with de minimis exemptions in certain fisheries. In 2018, 52% of the total catch in the North Sea and 19% in the Skagerrak was discarded. The reported Below Minimum Size landings for fleets that are under the landing obligation in the North Sea are currently much lower than would be suggested by information from catch monitoring programmes.

The Scottish Fisheries Sustainable Accreditation Group (SFSAG) is MSC certified for haddock, whiting, hake, plaice and saithe in the North Sea. 20 of its boats have trialled CCTV to help with monitoring catches, and the whole fleet has improved its gear to reduce bycatches of cod and spurdog. All nets are governed by the same mesh regulations, which require 120mm mesh cod-ends. In 2017, 27% of the overall TAC was allocated to this certified fishery.


In the European Union (EU), EU fishing vessels can fish up to 12 nautical miles of any Member State coast, and closer by agreement. There is overarching fisheries legislation for all Member States, but implementation varies between fisheries, Member States and sea basins.
The EU Common Fisheries Policy (CFP) is the primary overarching policy. Its key environmental objectives are to restore and maintain harvested species at healthy levels (above BMSY), and apply the precautionary and ecosystem-based approaches to fisheries management. To achieve the MSY objective, the MSY exploitation rate is supposed to be achieved by 2020, but this seems unlikely to happen.
The CFP also introduced a Landing Obligation (LO) which bans the discarding at sea of species which are subject to catch limits. Some exemptions apply to species with high post-capture survival, and where avoiding unwanted catches is very difficult. These exemptions are outlined in regional discard plans. Despite quota ‘uplift’ being granted to fleets under the LO, available evidence suggests there has been widespread non-compliance with the policy, and illegal and unreported discarding is likely occurring.
Multi-Annual Plans (MAPs) are a tool for implementing the CFP regionally, with one in place or being developed for each sea basin. They specify fishing mortality targets and ranges for the main targeted species, as well as lower biomass reference points. If populations drop below these points it should trigger a management response. The MAPs also empower Member States to jointly apply measures such as closures, gear or capacity limits, and bycatch limits. There is concern however that the MAPs do not provide adequate safeguards to maintain all stocks at healthy levels.
The EU Technical Measures regulation addresses how, where and when fishing can take place in order to limit unwanted catches and ecosystem impacts. There are common measures that apply to all EU sea basins, and regional measures that vary between sea basins. Measures include Minimum Conservation Reference Sizes (MCRS, previously Minimum Landing Sizes, MLS), gear specifications, mesh sizes, closed areas, and bycatch limits.
The Control Regulation, which is being revised in 2019, addresses application of and compliance with the above, e.g. keeping catches within limits, recording and sharing data, and satellite tracking of vessels over 12 metres (VMS).

Capture Information

Criterion score: 0.75 info

Plaice is mainly taken by beam trawlers in a mixed fishery with sole in the southern and central part of the North Sea. Beam trawl accounted for 52% of catches in 2018, otter trawl, 37%, and other gears, 11%. The overall capacity and effort of the North Sea beam trawl fleet has been substantially reduced since 1995, likely due to a number of reasons, including effort limitations between 2008 and 2016 for the recovery of the cod stock. Fishing effort of the beam trawl fleet has shifted towards the southern North Sea to target sole over the past decade. Juvenile plaice tend to be relatively abundant there, leading to relatively high discarding rates of small plaice. In addition, the minimum mesh size of 80 mm selects sole at the minimum conservation size, but generates high discards of plaice, which have a larger minimum size (27cm, although approximate size at which 50% of females mature or first spawn is around 30-34cm). With the recent substantial increases in biomass of the plaice stock, and higher proportion of older (and larger) fish in the northern North Sea, targeting plaice further north may become more economically favourable again. Mesh enlargement would reduce the catch of undersized plaice, but would also result in loss of marketable sole.

Technical management measures have caused a shift towards two categories of vessels: 2000 HP (the maximum engine power allowed) and 300 HP. The 300 HP vessels are allowed to fish within the 12-nautical mile coastal zone and in the Plaice Box - a partially closed area along the continental coast that was implemented in 1989. The area has been closed to most categories of vessels higher than 300 HP all year round since 1995. The most recent EU-funded evaluation reported the Plaice Box as having very little impact on the plaice stock.

Beam trawls have the potential to take relatively high quantities of bycatch (> 50% of catch weight) including demersal elasmobranchs and occasionally protected, endangered and threatened (PET) species (e.g. sharks and rays) in certain circumstances. Under the North Sea MAP, bycatch species should be managed under the precautionary approach if scientific information is not available, and otherwise managed according to the key CFP objectives. If stocks fall below trigger levels, measures can be brought in such as limits on characteristics or use of gear (e.g. mesh size, depth); time/area closures; and minimum conservation reference sizes.

Beam trawls interact with the seabed, potentially modifying bottom topography including damage and removal of some biogenic features and interacting with vulnerable marine habitats and benthic communities. However, the risk due to damage to vulnerable marine habitats is likely to be reduced given that most of the footprint of the gear occurs on core fishing grounds. Some spatial management is in place and is continually being developed, which will restrict the footprint of this gear on the seabed. However, there remains some uncertainty about the location of some sensitive seabed habitats so these remain at risk.

Alternatives

Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Dab
Halibut, Atlantic (Farmed)
Halibut, Pacific
Megrim
Plaice
Sole, Dover sole, Common sole
Sole, Lemon
Turbot (Caught at sea)
Turbot (Farmed)

References

EU, 2018. Regulation 2018/973 establishing a multiannual plan for demersal stocks in the North Sea and the fisheries exploiting those stocks. Available at https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0973&from=EN [Accessed on 02.07.2019].

EU, 2019. Bilateral Agreements: Norway Northern Agreement. Available at https://ec.europa.eu/fisheries/cfp/international/agreements/norway [Accessed on 02.07.2019].

ICES, 2018. Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 24 April - 3 May 2018, Oostende, Belgium. ICES CM 2018/ACOM: 22pp. Available at http://ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/acom/2018/WGNSSK/01-WGNSSK%20Report%202018.pdf [Accessed on 02.07.2019].

ICES. 2019. Plaice (Pleuronectes platessa) in Subarea 4 (North Sea) and Subdivision 20 (Skagerrak). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, ple.27.420, doi: 10.17895/ices.advice.4870. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/ple.27.420.pdf [Accessed on 03.07.2019].

MSC, 2019. Marine Stewardship Council Track a Fishery: SFSAG Northern Demersal Stocks. Available at https://fisheries.msc.org/en/fisheries/sfsag-northern-demersal-stocks/about/ [Accessed on 03.07.2019].

Seafish, 2019. RASS Profile: Plaice in the North Sea and Skagerrak (Subarea 4 and subdivision 3a.20), Beam trawls. Available at https://www.seafish.org/risk-assessment-for-sourcing-seafood/profile/plaice-in-the-north-sea-and-skagerrak-subarea-4-and-subdivision-3a-20-beam-trawls [Accessed on 03.07.2019].

WWF, 2019. Remote Electronic Monitoring in UK Fisheries Management 2017. Available at https://www.wwf.org.uk/sites/default/files/2017-10/Remote%20Electronic%20Monitoring%20in%20UK%20Fisheries%20Management_WWF.pdf [Accessed on 02.07.2019].