Sole, Lemon

Microstomus kitt

Method of production — Caught at sea
Capture method — Seine net
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea, Skagerrak and Kattegat, Eastern English Channel
Stock detail — 4, 3a, 7d
Picture of Sole, Lemon

Sustainability rating three info

Sustainability overview

Updated: February 2020.

Lemon sole is a valuable bycatch species in mixed demersal trawl fisheries and this stock is classed as data limited. The latest stock assessment undertaken in 2019 indicated that fishing mortality was not of concern and was below the proxy for maximum sustainable yield (FMSY). The state of the biomass is unknown in relation to reference points and whilst there is no evidence of overexploitation, there is also no evidence that the stock is increasing. The index of relative population size in this assessment decreased in comparison to previous years, but by less than 20%. Considering this and the likely significant reductions in fishing pressure on the stock in the last decade, the biomass has not been assessed as ‘of concern’ by MCS. The stock is currently managed under a combined total allowable catch (TAC) with witch flounder and whilst this is considered insufficient to manage catches, the International Council for Exploration of the Sea (ICES) have advised that the removal of the TAC for lemon sole would present a low risk of the stock being exploited unsustainably. Benthic seines do interact with the seabed and have the potential to cause some damage to sea floor habitats, but the majority of the interaction comes from ropes which have a lighter impact than otter and beam trawl fisheries.

There is a Fishery Improvement Project (FIP) in place for some UK fleets that are making progress towards being eligible for Marine Stewardship Council (MSC) certification. More info is available here.

Biology

Lemon sole is a widely distributed flatfish which is found in shelf waters of the North Atlantic, from the White Sea and Iceland southward to the Bay of Biscay. Lemon sole appears to prefer sandy and gravelly substrates, living deeper and at higher salinity and lower temperature than plaice or sole. Sexual maturity occurs in males at 3-4 years and at 4-6 years in females and between 20-30 cm. Lemon sole may live for about 17 years and can attain lengths of over 60 cm. They spawn in spring and summer, April to August.

Stock information

Criterion score: 0.25 info

Stock Area

North Sea, Skagerrak and Kattegat, Eastern English Channel

Stock information

The latest stock assessment undertaken by the International Council for Exploration of the Sea (ICES) in 2019 indicated that fishing mortality was not of concern and was below the proxy for maximum sustainable yield (FMSY). The state of the biomass is unknown in relation to reference points and whilst there is no evidence of overexploitation, there is also no evidence that the stock is increasing. The index of relative population size in this assessment decreased in comparison to previous years, but by less than 20%. Considering this and the likely significant reductions in fishing pressure on the stock in the last decade, the biomass has not been assessed as ‘of concern’ by MCS. ICES advises that when the precautionary approach is applied, catches should be no more than 4279 tonnes in each of the years 2020 and 2021.

The stock is considered data limited (ICES category 3) and so the assessment of biomass has drawn on a combination of survey data and catch data to provide an index of relative abundance. The fishing pressure has been estimated using a length-based indicator. ICES indicate that improved information on age and length distributions in landings and discards, from most countries participating in the fishery, would be required in order to conduct a fully analytical assessment. A fishery-independent index covering the entire distribution area of the stock and targeting all length classes of lemon sole could also improve the assessment.

Management

Criterion score: 0.5 info

Lemon sole is considered a valuable bycatch species and there are no specific management objectives for this species in this region. The stock is currently managed under a European Union (EU) combined total allowable catch (TAC) with witch flounder and the International Council for Exploration of the Sea (ICES) have indicated that should TAC management still continue, it should be under single TACs for each stock/species that correspond with the stock areas. The current TAC only covers ICES Division 2.a and Subarea 4 and so no does not cover catches in 3.a and 7.d. In 2018 though, ICES advised that the removal of the TAC for lemon sole would present a low risk of the stock being exploited unsustainably. This was because there was no indication of a targeted fishery for lemon sole - unlike witch in some areas. Catches of lemon sole in recent years have been below those recommended by ICES.

As a bycatch species, management under the EU North Sea Multiannual Management Plan (NSMAP) for demersal stocks (2018) applies. The NSMAP aims to ensure that exploitation of living marine biological resources restores and maintains populations of harvested species above levels which can produce the Maximum Sustainable Yield (MSY) and that the precautionary approach to fisheries management is applied. Bycatch stocks do not have specific targets and limits under the NSMAP but are supposed to be managed in accordance with the best available scientific advice and the precautionary approach when no adequate scientific information is available.

There is no minimum conservation reference size for lemon sole, meaning it can be landed at any size and it is currently subject the EU landing obligation, meaning it should be legally retained by fisheries in this region and not discarded.

There is a Fishery Improvement Project (FIP) in place for some UK fleets that are making progress in addressing issues of environmental concern. The FIP commenced in 2017 and is aiming to be eligible for an unconditional pass of the Marine Stewardship Council standard by 2022. More information is available at fisheryprogress.org.

General EU fisheries management.

In the 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 was supposed to be achieved by 2020, but this seems very unlikely to happen for all fisheries.
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 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: 0.25 info

Lemon sole are generally taken as bycatch in mixed fisheries by otter trawlers (73%), beam trawlers (22%), demersal seines (2%), and gillnets (2%). Bottom trawls and seines disturb seabed habitats and in the North Sea and such gears have reduced the biomass and production of bottom-dwelling organisms. Sustained fishing has resulted in a shift from communities dominated by relatively sessile, emergent and high biomass species to communities dominated by infaunal, smaller bodied and faster growing organisms. Habitat impacts are related to the types of seabed communities and other sources of seabed disturbance such as wave and tidal action. The most sensitive species are emergent epifauna and slow growing reef building communities. Demersal seiners have been reported to have amongst the largest hourly habitat footprints of the major bottom towed gear types, but also have some of the smallest proportions of impact at the subsurface level. As a result, they are deemed to have less benthic impact than otter and beam trawling.

Demersal seine fisheries can encounter bycatch of other species, including juveniles of commercial species, but as lemon sole itself is considered a bycatch species of other targeted fisheries (often for common sole and plaice), this component has not been assessed in this rating. The gear type is likely to encounter occasional bycatch of some vulnerable species like common skate, but ICES information suggests this is more of an issue in the Celtic Seas region as opposed to the North Sea.

Some spatial management is in place but there remains a need to implement management measures in many designated marine protected areas to allow for the protection and recovery of these areas and sensitive designated features. There are MPAs designated to protect seabed features from damaging activities within the region that this assessment applies. The fishery overlaps with parts of these MPAs, but the proportion of the catch coming from these areas is expected to be relatively low in relation to the whole unit of assessment (i.e. less than 20% of the catch) and so these impacts have not been assessed within the scale of this rating. Given the important role that MPAs have in recovering the health and function of our seas, MCS encourages the supply chain to identify if their specific sources are being caught from within MPAs. If sources are suspected of coming from within designated and managed MPAs, MCS advises businesses to: establish if the fishing activity is operating legally inside a designated and managed MPA; and to request evidence from the fishery or managing authority to demonstrate that the activity is not damaging to protected features or a threat to the conservation objectives of the site[s].

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

Eigaard, O.R., Bastardie, F., Breen, M., Dinesen, G.E., Hintzen, N.T., Laffargue, P., Mortensen, L.O., Nielsen, J.R., Nilsson, H.C., O'Neill, F.G., Polet, H., Reid, D.G., Sala, A., SkOld, M., Smith, C., Sorensen, T.K., Tully, O., Zengin, M., Rijnsdorp, A.D., 2016. Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions. ICES Journal of Marine Science, Volume 73, Issue suppl 1. Pages i27-i43. Available at https://academic.oup.com/icesjms/article/73/suppl_1/i27/2573989 [Accessed 9.12.2019].

EU, 2019. Technical measures regulation. EU 2019/1241. Available at https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32019R1241 [Last accessed 13.09.2019].

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].

FAO, 2001. Fishing gear types; bottom trawls. Available at http://www.fao.org/fishery/geartype/205/en [Last accessed 23.09.2019].

Hiddink, J., Jennings, S., Kaiser, M., Queiros, A., Duplisea, D. and Piet, Gerjan. 2006. Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences 63 (2006) 4. 63. 10.1139/f05-266.

ICES, 2019. Bycatch of protected and potentially vulnerable marine vertebrates - review of national reports under Council Regulation (EC) No. 812/2004 and other information. Published 30 August 2019. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/byc.eu.pdf [Last accessed 24.2.2020].

ICES, 2019. Greater North Sea Ecoregion - Ecosystem overview. Published 12 December 2019. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/EcosystemOverview_GreaterNorthSea_2019.pdf [Last accessed 24.2.2020].

ICES, 2019. Lemon sole (Microstomus kitt) in Subarea 4 and divisions 3.a and 7.d (North Sea, Skagerrak and Kattegat, eastern English Channel). ICES Advice on fishing opportunities, catch, and effort Greater North Sea ecoregion. Published 28 June 2019 Version 2: 3 September 2019. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/lem.27.3a47d.pdf [Last accessed 27.02.2020].

ICES, 2018. EU request for ICES to provide advice on a revision of the contribution of TACs to fisheries management and stock conservation. ICES Special Request Advice Northeast Atlantic ecoregions. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/Special_requests/eu.2018.15.pdf [Last accessed 27.02.2020].

Jager, Z., Witbaard, R., Kroes, M., 2018. Impact of demersal & seine fisheries in the North Sea areas Frisian Front and Central Oyster Grounds. Available at https://www.narcis.nl/publication/RecordID/oai:imis.nioz.nl:300074 [Last accessed 27.02.2020].

Lakkeborg, S. 2005. Impacts of trawling and scallop dredging on benthic habitats and communities. FAO Fisheries Technical Paper. No. 472. Rome, FAO. 2005. 58p.

Tillin, H.M., Hiddink, J.G., Jennings, S. and Kaiser, M. J., 2006. Chronic bottom trawling alters the functional composition of benthic invertebrate communities on a sea-basin scale. Marine Ecology Progress Series. Vol. 318. 31-45.