Sole, Dover sole, Common sole

Solea solea

Method of production — Caught at sea
Capture method — Beam trawl
Capture area — North East Atlantic (FAO 27)
Stock area — Irish Sea
Stock detail — 7a
Picture of Sole, Dover sole, Common sole

Sustainability rating four info

Sustainability overview

Updated: July 2019.

This stock is slowly recovering, but not yet at sustainable levels, while fishing pressure is close to 0. While there has been no management or recovery plan for this stock, decreasing Total Allowable Catches and the introduction of technical measures seem to have successfully reduced the fishing pressure. Trawling can have impacts on the seabed, particularly beam trawling.

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

Irish Sea

Stock information

This stock is slowly recovering, but not yet at sustainable levels, while fishing pressure is close to 0.

Spawning stock biomass (SSB) was below Blim (2,500t) between 2004 and 2017, and reached a record low of 883t in 2014. It then increased to 2,627t in 2018, between Blim and MSY Btrigger (3,500t). Fishing mortality (F) has been declining since the late 1980s and in 2018 was 0.0138, far below FMSY (0.20) and the lowest on record. Recruitment from 2011-2014 was the lowest on record, although higher recruitment was observed in 2016 and 2018.

ICES advises that when the MSY approach is applied, catches in 2020 should be no more than 561 tonnes. This is a 36% increase on the previous year’s advice owing to the increase in stock size, and is projected to result in a 6% decrease in SSB.

Management

Criterion score: 0.5 info

The EU’s Western Waters Multi Annual management Plan (MAP), which came into force in March 2019, does not cover sole in the Irish Sea, and so there is no management plan for this stock.

In most years between 2007 and 2018, scientific advice was for zero catch. TACs during that time slowly reduced from 620t to 40t since 2016. Catches have reduced, in line with TACs, and fishing pressure is now close to 0. Discard rates of sole are low (averaging 3.5% between 2016 and 2018). This would suggest that measures have been successful in managing fishing pressure on this stock.


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

Sole are predominantly caught by beam trawlers (66% of 2018 catch) and otter trawls (30% of 2018 catch) in the Irish Sea. Whilst discards of sole are known to be low, there can often be high amounts of discarding of other species and bycatch of cod and whiting are of concern as these stocks are in a very poor condition in the Irish Sea. Minimum mesh sizes are in place (80-120mm), and beam trawlers fishing with mesh sizes equal to or greater than 80 mm are obliged to have 180 mm mesh sizes in the entire upper half of the anterior part of their net to allow escapes. Beam trawling, especially using chain-mat gear, is known to have a significant impact on the benthic communities, although less so on soft substrates. Full square mesh codends are being tested in order to reduce the capture of benthos and improve selectivity.

Beam and otter trawling can have impacts on the seabed. Beam trawlers often use tickler chains to disturb fish from the seabed. Beam trawling is not a well targeted fishing activity, with poor selectivity and the potential to catch a wide variety of non-target species, including benthic invertebrates disturbed from the seabed. Some beam trawlers use benthic drop-out panels that release about 75% of benthic invertebrates from the catches. A seasonal closure of the spawning grounds for cod in the western part of the area doesn’t affect the sole fishery, which mainly operates in the east.

Minimum landing size for sole in EU waters is 24cm. Sole mature at 30cm.

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

ICES. 2019. Working Group for the Celtic Seas Ecoregion (WGCSE). ICES Scientific Reports. 1:29. 1078 pp. doi: 10.17895/ices.pub.4982. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/Fisheries%20Resources%20Steering%20Group/2019/WGCSE/01_WGCSE_2019.pdf [Accessed on 12.07.2019].

ICES. 2019. Sole (Solea solea) in Division 7.a (Irish Sea). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, sol.27.7a, https://doi.org/10.17895/ices.advice.4803. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/sol.27.7a.pdf [Accessed on 12.07.2019].