Sole, Dover sole, Common sole

Solea solea

Method of production — Caught at sea
Capture method — Gill or fixed net
Capture area — North East Atlantic (FAO 27)
Stock area — English Channel: East
Stock detail — 7d
Picture of Sole, Dover sole, Common sole

Sustainability rating three info

Sustainability overview

Updated: July 2019.

Eastern English Channel sole is in a poor state, and fishing mortality has only recently fallen to sustainable levels. Management includes a mixture of catch limits and technical measures, but there is no recovery plan in place, although some specific measures were brought in some years ago in response to the poor stock status. Recent TACs and catches have been, on average, 30% above the scientific advice. This stock is caught by a mixture of bottom trawling (otter and beam) and trammel netting. Trawling can have significant habitat impacts, especially beam trawling, and a number of species can be bycaught by it - especially plaice. Trammel netting tends to have few habitat impacts, but bycatch can also be an issue with this gear. Bycatch of harbour porpoise in the North Sea and Eastern Channel is not considered to be a threat to the population, but localised depletion may be an issue in some areas.

Biology

Sole is a right-eyed flatfish (eyes on the right hand side of the body) and belongs to the family of flatfishes known as Soleidae. It spawns in spring and early summer in shallow coastal water, from April to June in the southern North Sea, from May-June off the coast of Ireland and southern England, and as early as February in the Mediterranean. Common sole become sexually mature at 3-5 years, when 25-35cm long, the males being somewhat smaller than the females. It can attain lengths of 60-70cm and weigh 3kg.The maximum reported age is 26 years. Sole is a nocturnal predator and therefore more susceptible to capture by fisheries at night than in daylight.

Stock information

Criterion score: 0.5 info

Stock Area

English Channel: East

Stock information

Eastern English Channel sole is in a poor state, and fishing mortality has only recently fallen to sustainable levels.

The spawning-stock biomass (SSB) has decreased since a peak of 22,898 tonnes in 2013, and in 2018 was 14,294 - close to Blim (13,751t) and below MSY BTrigger (19,251t). Fishing mortality (F) has been decreasing since 2014 and is just below FMSY (0.256) in 2017, at 0.24. Recruitment has been fluctuating without trend, and there has been no strong recruitment since 2011.

ICES advises that when the MSY approach is applied, catches in 2019 should be no more than 2571 tonnes, a third lower than advised for catches in 2018. The decrease is owing to a combination of an overestimation of the 2015 recruitment in the assessment last year, and because SSB(2019) is well below MSY Btrigger. This advice would lead to a 9% increase in SSB, reaching 16,615t. To reach MSY BTrigger by 2020 would require 0 fishing mortality.

There is a decreasing trend in weight- and length-at-age from 2004 onwards, which is of concern. New strong year classes are not entering the population, and the older fraction of the population is being fished.

Management

Criterion score: 0.5 info

This stock is covered by the EU’s Western Waters Multi Annual management Plan (MAP), which uses ranges for target fishing pressure (F) when the stock is above MSY BTrigger. As this stock is below MSY BTrigger, F is reduced and ranges are not used.

Between 2013 and 2017, TACs averaged 130% of the advice, although in 2018 the TAC was 88% of the advice. Since 2016, advice has been given for total catch (landings + discards). Total catches between 2013 and 2017 were in line with or just below TACs, with discards making up 10% of the catch on average. This results in catches being around 30% above the advice (in 2015 they were double the advice). The stock is close to BLim.

Sole in the eastern English Channel is fully under the landing obligation since 2018 (partially since 2016). However, there is no indication that sole that would formerly have been discarded are now being landed and reported as Below Minimum Size (BMS). This is based on the observation that BMS landings reported to ICES are currently much lower than the estimates of unwanted catches from observer programs, which are estimated at 8.0% of the total catch.

Management of sole in the eastern English Channel is by TAC and technical measures (see capture method tab for details).

The trammel net eastern Channel sole fishery was certified by the Marine Stewardship Council, but this is currently suspended owing to the poor stock status.


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: 0.5 info

Catch in 2017 was 2428 tonnes, of which 8% was unwanted. Of the wanted portion of the catch, trammel or gillnets accounted for 43%, beam trawls: 39%, and otter trawls: 17%.

Technical measures applicable to the mixed flatfish beam-trawl fishery affect both sole and plaice. The minimum mesh size of 80 mm for the sole fishery generates high discards of plaice, which have a larger minimum conservation reference size (MCRS) (27cm) than sole (24cm). The use of larger mesh sizes would reduce the catch of undersized plaice and sole, but would also result in a loss of marketable sole in the short term.

Mesh size restrictions in place are 80 mm for beam trawling and otter trawlers. Fixed nets for the sole fisheries are required to use 100 mm mesh since 2002, although an exemption to permit 90 mm has been in force since that time. In response to the drop in SSB and the poor recruitment in 2012, the two main countries participating in the fishery (France and Belgium) implemented additional conservation measures, mainly focussed on trawling. France engaged in 2016 to strengthen the protection of nursery areas; increase the area closed to fishing within the nursery areas; and increase the MCRS to 25cm, where appropriate. From 11 March until 31 December 2017, the MCRS for Belgian vessels also increased to 25 cm.

Trammel nets are a wall of net divided into three layers. An inner fine-meshed net is sandwiched between two outer, larger meshed nets. The net is anchored at the base and floated by the headline, allowing it to hang vertically. The inner net is looser than the outer ones, ensuring that the fish become entangled within it. This is a method with little or no impact on the seabed but it can be associated with bycatch, including harbour porpoises, seals, rays, skates and seabirds. Reports indicate that there is concern regarding the bycatch of cetaceans, particularly harbour porpoise, by gillnets. One of the areas of most concern is off the South West of England, where areas of higher gillnet fishing effort coincide with areas of larger harbour porpoise populations. However, these reports are based on highly uncertain data which cannot indicate the likelihood of bycatch either causing populations to decline or preventing populations from recovering. Progress on this issue is being made in some areas, with Defra leading work to improve monitoring and mitigation of cetacean bycatch (“Hauling Up Solutions”). A pilot project trialling self-reporting of bycatch is taking place in Cornwall, potentially backed up by electronic monitoring and VMS in time, and trialling the use of pingers and other mitigation technologies, which are known to deter harbour porpoise from entanglement in nets. MCS is pleased to see this progress, but notes that if catch rates of harbour porpoise do not show a decrease then scoring of this capture method may be affected. Because of gillnets’ durability (they are made of nylon), if lost, they can continue to fish for several weeks before becoming tangled and bundled up, a phenomenon known as ‘ghost fishing’. However, static nets, as with all gear, represent an investment by fishermen, and therefore there are incentives to avoid losing or damaging gear.

Fish caught in trammel nets are often very good quality as they are not damaged by the capture process.

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)
Megrim
Plaice
Sole, Dover sole, Common sole
Turbot (Caught at sea)
Turbot (Farmed)

References

EU, 2019. Regulation (EU) 2019/472 of the European Parliament and of the Council of 19 March 2019 establishing a multiannual plan for stocks fished in the Western Waters and adjacent waters, and for fisheries exploiting those stocks. Available at https://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1554387217276&uri=CELEX:32019R0472 [Accessed on 12.07.2019].

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 15.07.2019].

ICES, 2018. Sole (Solea solea) in Division 7.d (eastern English Channel). ICES Advice 2018, sol.27.7d, Version 3: 14 November 2018. doi: 10.17895/ices.pub.4456. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/sol.27.7d.pdf [Accessed on 15.07.2019].

Marine Stewardship Council, 2019. FROM Nord North Sea and Eastern Channel trammel net sole. Available at https://fisheries.msc.org/en/fisheries/from-nord-north-sea-and-eastern-channel-trammel-net-sole/@@assessments [Accessed on 15.07.2019].

Sustainable Fisheries Partnership, 2014. FishSource profile: Common sole, Western English Channel. Available at https://www.fishsource.org/stock_page/768 [Accessed 15.07.19].

Seafish, 2019. RASS Profile: Sole, Division 7d (Eastern English Channel), Trammel nets. Available at https://www.seafish.org/risk-assessment-for-sourcing-seafood/profile/sole-in-eastern-english-channel-division-7d-trammel-nets [Accessed on 22.07.2019]