Capture method — Demersal otter trawl
Capture area — North East Atlantic (FAO 27)
Stock area — Celtic Sea, west of Ireland, Bay of Biscay
Stock detail — 7b-k, 8a, 8b, 8d
Updated: December 2019
Two species of megrim are landed to west of Britain and in the Bay of Biscay, megrim (Lepidorhombus whiffiagonis) and four-spot megrim (L. boscii). The former is more common and the only one assessed. The spawning-stock biomass of L. whiffiagonis has been above target points (MSY BTrigger) since 2008 and continues to increase - in 2019 it was 100,393 tonnes, the highest on record. Fishing mortality has decreased since 2005, and in 2018 it was below the target threshold (FMSY) for the first time. Management measures are in place, but as catch limits apply to both species this hinders the ability to prevent overexploitation of either species. However, currently the stock is in a good state and total catches have been equal to or below the advice. In 2018 trawling accounted for 97% of landings. There are a number of Protected, Endangered and Threatened species in the Celtic Seas and Western Channel, including basking sharks, commons skates and spurdog, which can be vulnerable to trawling. Demersal otter trawls use doors to hold nets open that penetrate the seabed, resulting in the abrasion of habitat features. Beam trawling, especially using chain-mat gear, is more damaging to the seabed as it is a heavy gear that is designed for trawling over rough grounds. There are now several areas of deep water seabed on which all bottom trawling is banned to protect vulnerable deep water habitats within Celtic Sea and Biscay.
A common flatfish found in shelf seas throughout the northeast Atlantic. Megrim spawns in spring in deep water off Iceland, and between January and April along the edge of the continental shelf to the southwest and west of the British Isles. It is found at depths ranging from 50-800 m, but with the highest abundance around 100-300 m. For both sexes combined, 50% of individuals mature at about 20 cm at 2.5 years old. Males reach first maturity at a lower length and age than females. Megrim can attain a length of about 60 cm, although more usually 35-45 cm, and a maximum age of 14-15 years.
Criterion score: 0 info
Celtic Sea, west of Ireland, Bay of Biscay
Two species of megrim are landed to west of Britain and in the Bay of Biscay, megrim (Lepidorhombus whiffiagonis) and four-spot megrim (L. boscii). The former is more common and the only one assessed.
The spawning-stock biomass (SSB) of L. whiffiagonis has been above MSY Btrigger (41,800 tonnes) since 2008 and continues to increase. In 2019 it was 100,393 tonnes - the highest point in the time series. Fishing mortality (F) has decreased since 2005, and in 2018 it was 0.179 - below FMSY (0.191) for the first time. Recruitment (R) has been relatively stable throughout the time series, although the last two years were above average.
ICES advises that when the EU multiannual plan (MAP) for Western waters and adjacent waters is applied, catches in 2020 that correspond to the F ranges in the MAP are between 13,218 and 28,838 tonnes. According to the MAP, catches higher than those corresponding to FMSY (19,982 tonnes) can only be taken under conditions specified in the MAP, while the entire range is considered precautionary when applying the ICES advice rule. This is a 6% increase in advice from the previous year, owing to the decrease of fishing mortality and the above average recruitment.
Management of catches of the two megrim species, L. whiffiagonis and L. boscii, under a combined species TAC prevents effective control of the single-species exploitation rates, and could lead to overexploitation of either species.
Criterion score: 0.75 info
Management measures are in place, but as catch limits apply to both species this hinders the ability to prevent overexploitation of either species. However, currently the stock is in a good state and total catches have been equal to or below the advice.
The EU multiannual plan (MAP) for stocks in in the Western Waters and adjacent waters applies to these stocks. According to the MAP, for data-limited species such as four-spot megrim (L. boscii), fishing opportunities should be based on the best available scientific advice - but no ICES assessment has been requested and therefore there is no advice for this species. For megrim (L. whiffiagonis), which is fully assessed, the MAP includes upper and lower ranges for fishing pressure (F). The two megrim species are not totally separated in the landings and a single Total Allowable Catch covers them both, although species-specific landings are estimated by ICES. ICES considers that a combined TAC prevents effective control of individual species’ exploitation rates, and could lead to overexploitation of either species, although currently L. whiffiagonis is in a healthy state and, as of 2018, is not being overfished.
On average from 2015-2019, TACs have been set 4% above the advice. From 2014-2018, landings averaged 75% of the TAC, although in the most recent two years they were over 90%. Discards in that time have averaged 17% of the total catch, and total catches (including discards) have been equal to or below the advice.
The minimum landing size of megrim was reduced from 25 to 20 cm length in 2000.
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).
Criterion score: 0.5 info
In 2018 trawling accounted for 97% of landings. Most catches are by France, the UK (England and Wales), Spain and Ireland. They are bycatch in demersal fisheries, as well as in targeted mixed fisheries for megrim, hake, anglerfish, Nephrops and others. Otter trawlers account for the majority of Spanish landings from ICES area 7. Most UK landings of megrim are made by beam trawlers fishing in the southwest of England and Wales. Irish megrim landings are largely made by multi-purpose vessels fishing in to the west and south of Ireland for gadoids such as cod and haddock, as well as plaice, sole and anglerfish.
There are a number of Protected, Endangered and Threatened species found in the Celtic Seas, including the Western Channel, including basking sharks, commons skates and spurdog. These can be vulnerable to demersal trawling. Other potentially impacted species and habitats in the Southwest UK include the pink sea fan Eunicella verrucosa, which is listed as ‘vulnerable’ by the IUCN. Reduced feeding success and growth rates of benthivorous fish are potential secondary effects of trawling impacts, which has been observed for European plaice in gravel substrates in the Celtic Sea. Trawling in the Celtic Sea has also been associated with declining length-weight ratios for lemon sole, megrim and cod, implying that reduced prey availability imposed by trawling may lead to reduced carrying capacity, and these effects may compromise recovery of threatened stocks and ecosystems.
Demersal otter trawls use doors to hold nets open that penetrate the seabed, resulting in the abrasion of habitat features. The ground ropes, sweeps and bridles of the trawl can also be abrasive. Most otter trawling occurs within the same historical areas, where yields are high and it is safe to trawl. Bycatches of non-target species can make up a high proportion of catch weight in demersal otter trawls, and there may also be bycatch of protected, endangered and threatened species in certain circumstances. For example, bycatch of skates, rays and sharks (elasmobranchs) take place in most European otter trawl fisheries. EU vessels are required to report significant catches of corals and sponges to assist mapping these communities and move fishing operations at least 2 miles when they are encountered. There are now several areas of deep water seabed on which all bottom trawling is banned to protect deep vulnerable deep water habitats within Celtic Sea and Biscay.
A number of areas are closed to fishing at certain times of the year, e.g. the Trevose box, an area of sea around 11,400 square miles extending from Trevose head in Cornwall to the Gower peninsular in South Wales from January - March. This is the spawning period for a number of demersal stocks, so while it is primarily intended to reduce catches of spawning cod, other stocks are likely to benefit. However, beam trawlers have been allowed to fish there since 2005.
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)
Sole, Dover sole, Common sole
Turbot (Caught at sea)
ReferencesICES, 2018. ICES Stock Annex: Megrim (Lepidorhombus whiffiagonis) in divisions 7.b-k, 8.a,b,d (west and southwest of Ireland, Bay of Biscay). Available at https://www.ices.dk/sites/pub/Publication%20Reports/Stock%20Annexes/2018/meg.27.7b-k8abd_SA_2018.pdf [Accessed on 12.12.2019].
ICES, 2019. Megrim (Lepidorhombus whiffiagonis) in divisions 7.b-k, 8.a-b, and 8.d (west and southwest of Ireland, Bay of Biscay). In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, meg.27.7bk8abd, https://doi.org/10.17895/ices.advice.4763 [Accessed on 11.12.2019].
ICES. 2019. Working Group for the Bay of Biscay and the Iberian Waters Ecoregion (WGBIE). ICES Scientific Reports. 1:31. 692 pp. http://doi.org/10.17895/ices.pub.5299. [Accessed on 12.12.2019].
Seafish, 2016. RASS Profile: Megrim, Western Approaches and Bay of Biscay, deepwater otter trawl. Available at https://www.seafish.org/risk-assessment-for-sourcing-seafood/profile/megrim-western-approaches-and-bay-of-biscay-deepwater-otter-trawl [Accessed on 12.12.2019]
Seafish, 2016. RASS Profile: Megrim, Celtic Sea, Beam trawl. Available at https://www.seafish.org/risk-assessment-for-sourcing-seafood/profile/megrim-celtic-sea-beam-trawl [Accessed on 12.12.2019]