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, English Channel (East)
Stock detail — 4, 3a, 7d
Picture of Witch, Witch flounder, Torbay sole

Sustainability rating four info

Sustainability overview

Updated: July 2020.

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 taken as bycatch in the mixed-species demersal otter trawl fishery. Bottom trawling can have impacts on the seabed and bycatch a wide variety of species.

Biology

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: 0.5 info

The stock of witch in the North Sea is in a good state, but fishing pressure is above sustainable levels.

Spawning stock biomass (SSB) was below Blim (3069 tonnes) in 2010, but increased to above MSY Btrigger (4745 tonnes) in 2014 and in 2020 was 5644 tonnes. MSY Btrigger was set equal to Bpa as it was not considered likely that the stock had been fished at FMSY in the last 5 years. Until 2013, fishing mortality (F) was above FMSY (0.154) and Fpa (0.2). Since then, it has fluctuated around Fpa and in 2019, F was equal to Fpa.

Recruitment of the stock has shown a decreasing trend since 2009 and catches have increased in the same period. Despite two large recruitment events in 2009 and 2010, recently recruitment has been fluctuating at a low level. The decreasing recruitment in the last decade, combined with the increasing catches may potentially reduce the biomass of the stock below the biological reference points.

North Sea witch landings declined from a peak in the 1990s to a low at the end of the 2000s, but from 2011 a general increasing trend is observed. ICES advises that when the MSY approach is applied, catches should be no more than 1733 tonnes. Catch advice has increased by 5% due to continued high SSB and a reasonable recent recruitment. Previous advice was given using a precautionary approach and in 2020, this has changed to an MSY advice basis.

Management

Criterion score: 0.75 info

Management of witch in the North Sea is not following scientific advice, and overfishing is being allowed to take place.

Witch and lemon sole are largely caught by different fisheries in different areas but are managed under a combined species Total Allowable Catch (TAC). Furthermore, the TAC area (Subarea 4 and Division 2.a) does not coincide with the stock area (Subarea 4 and Divisions 3.a and 7.d). This may hinder effective management and could potentially lead to the overexploitation of witch. As witch is mainly a bycatch species in mixed fisheries, a TAC alone may not be appropriate as a management tool. The International Council for Exploration of the Sea (ICES) recommends that a single-species TAC for the entire witch stock (Subarea 4 and Divisions 3.a and 7.d) would be more appropriate.

The Landings Obligation does not apply to bycatch species. Discards from 2002-2018 ranged between 9.5% and 23.3% of total catches. There is no official Minimum Landing Size (MLS) specified in EU waters. However, in most of the countries reporting catches, the landing of witch below 28cm is prohibited.




The UK is due to leave the EU on 31st December 2020, and new UK Fisheries legislation is being developed during 2020. MCS will update ratings with new management information when new legislation comes into force.

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.

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 (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 2.07.2020].

ICES. 2020. Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK). ICES Scientific Reports. 2:61. 1140 pp. http://doi.org/10.17895/ices.pub.6092 [Accessed on 12.07.2020].

ICES. 2020. 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, 2020. ICES Advice 2020, wit.27.3a47d. https://doi.org/10.17895/ices.advice.5936. [Accessed on 12.07.2020].

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 09.07.2020].