Witch, Witch flounder, Torbay sole

Glyptocephalus cynoglossus

Method of production — Caught at sea
Capture method — Demersal otter trawl
Capture area — North East Atlantic (FAO 27)
Stock area — North Sea, Skagerrak and Kattegat, eastern English Channel
Stock detail — 4, 3a, 7d
Picture of Witch, Witch flounder, Torbay sole

Sustainability rating five info

Sustainability overview

Updated: July 2019.

While this stock is currently not in an overfished state, the approach to setting Total Allowable Catches (TACs) has allowed significant overfishing to take place throughout the history of the fishery. In addition, management is not following scientific advice as there is a combined TAC with lemon sole: a single-species TAC would be preferable. Witch is bycaught in the mixed-species demersal otter trawl fishery. Bottom trawling can have impacts on the seabed and bycatch a wide variety of species.


Witch is common in the northern North Sea, west of the British Isles, in Icelandic waters and along the North American east coast. It is a right-eyed flat fish (both eyes on the right-hand side of the body) belonging to a group of fish known as the family Pleuronectidae. Witch spawn in summer, have a slow growth rate, and reach sexual maturity in 3-4 years. Witch on average live for about 14 years, but the maximum reported age is 25 years. The species is mainly found on soft sea bottoms, mostly clay or clean sand, around 100-400 m depth. Their main diet consists of crustaceans, worms, brittle stars and fish.

Stock information

Criterion score: 0.75 info

Stock Area

North Sea, Skagerrak and Kattegat, eastern English Channel

Stock information

The stock is in a good state, but fishing pressure is considerably above sustainable levels.

Fishing mortality (F) has been above FMSY (0.154) and Fpa (0.2) since the beginning of the time-series in 1950, except in 2013 when it was 0.195. It fluctuated around Flim (0.3) from 1950-1998, increasing to a high of 0.43 in 2002, and then dropping below it in 2011. In 2018 it was 0.24 - above Fpa but below Flim. Spawning-stock biomass (SSB) was below Blim (3,069t) in 2010, but increased to above MSY BTrigger in 2014 and 2018 was 5,217t. MSY Btrigger is the same for this stock as Bpa - 4,745t. Recruitment of young fish into the stock has declined since 2010 and current levels are among the lowest on record.

As part of the EU multiannual plan (MAP) for demersal fisheries in the North Sea, in which this stock is considered bycatch, the EC requested that ICES provide advice based on the precautionary approach (Fpa) rather than MSY. ICES advises that catches of up to 1,651 tonnes are considered to be in line with Fpa, which is projected to lead to an 11.7% decrease in the stock between 2020 and 2021. However, even under a 0 fishing pressure scenario, ICES predicted that the stock would drop below MSY BTrigger in 2020. The precautionary advice is a 31% decrease owing to a changed perception of the stock: in 2018 ICES carried out a benchmark for this stock, moving it from category 3 (data limited) to category 1 (meaning that reference points are now available). This would suggest that in future years, advice should be given based on an MSY approach rather than the precautionary approach.


Criterion score: 0.75 info

Management is not following scientific advice, and overfishing is being allowed to take place.

Witch is mainly a bycatch species in mixed fisheries. Witch and lemon sole are largely caught by different fisheries in different areas but are managed under a combined species TAC. This may hinder effective management and could potentially lead to the overexploitation of witch: a single-species TAC for the entire witch stock (areas 3a, 4, 7d), would be more appropriate. In recent years, while advised catches for witch have been around 2,200-2,900t, total catches have been above 3,000t. Furthermore, as it is mainly a bycatch species in mixed fisheries, a TAC alone may not be appropriate as a management tool.

This stock is covered by the EU’s North Sea Multi Annual management Plan (MAP), under which it is considered to be a bycatch species. According to the MAP, bycatch species are managed using the precautionary approach, rather than an MSY-based approach, “when no adequate scientific information is available”. Up until 2018, this was a category 3 stock and the precautionary approach was appropriate. However, in 2019 this is now a category 1 stock, meaning information regarding stock size and fishing pressure is available, and the European Commission could request advice according to an MSY approach. However, the EC requested advice according to the precautionary approach, resulting in catch advice for 2020 being above FMSY. This could be cause for concern, but it remains to be seen whether the EC will act on this advice. It is of note, however, that fishing pressure has been above FMSY and Fpa since the beginning of the time-series in 1950, and has fluctuated around Flim for most of that time. Meanwhile, even under a 0 fishing pressure scenario, ICES predicted that the stock will drop below MSY BTrigger in 2020.

The Landings Obligation does not apply to bycatch species. Discards from 2002-2018 ranged between 9.5% and 23.3% of total catches.

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

Bottom otter trawl accounted for 90.5% of catches in 2018. Bottom trawling can have impacts on the seabed and bycatch a wide variety of species. If trawlers visit the same grounds repeatedly, the disruption to the seabed can cause long-term changes in the local ecosystem. In a mixed fishery, such as this one, in which witch is bycaught, making gear more selective can be challenging as different target species have different selectivity requirements.

This stock is mostly caught by Denmark and the UK, with some catches by Norway, Sweden, and the Netherlands. There is no official Minimum Landing Size specified for this stock, but most of the countries reporting catches prohibit the landing of witch below 28cm. Witch mature at around 30-34 cm. Females mature at a later age and larger size than males.


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.

Halibut, Atlantic (Farmed)
Sole, Dover sole, Common sole
Turbot (Caught at sea)
Turbot (Farmed)


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].

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. Witch (Glyptocephalus cynoglossus) in Subarea 4 and divisions 3.a and 7.d (North Sea, Skagerrak and Kattegat, eastern English Channel). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, wit.27.3a47d, doi: 10.17895/ices.advice.4879. Available at http://ices.dk/sites/pub/Publication%20Reports/Advice/2019/2019/wit.27.3a47d.pdf [Accessed on 10.07.2019].

Seafish, 2017. RASS Profile: Witch sole, Northern stock, demersal trawl. Available at https://www.seafish.org/risk-assessment-for-sourcing-seafood/profile/witch-sole-northern-stock-demersal-trawl [Accessed on 10.07.2019]