A large flatfish that can reach up to 1 metre in length, although fish of this size are very rarely seen today.

In brief

• Large, distinctively-shaped flatfish
• Although it is considered to be of Least Concern globally, it faces increased pressure in Britain and Europe
• Noted as declining, with more data required to accurately assess
• At risk of overexploitation through commercial fishing

Species description: A large flatfish that can reach up to 1 m in length and weigh up to 25 kg (although today such specimens are rare). More commonly 50-80 cm. It has a distinctive asymmetric disk-shaped body, and is left-eyed. It is usually dull brown to grey on top with lots of dark coloured flecks and speckles to help it blend into the surrounding habitat, this colouration is variable and it can adapt it to match the current background. It is bright white on its underside, sometimes with a few dark blotches. There is strong speckling on the tail.

Similar species: Unlikely to be confused with any other species, due to distinctive body shape.

How to see this species: They prefer sandy or gravelly sediment, usually between 20-80 m although juveniles may be spotted closer to shore. Most records for Northern Ireland are off the Irish Sea section of the County Down coast, with a few scattered sightings in Belfast Lough and along the north coast.

Current status: Declining. Data deficient for Northern Ireland. Classified as Least Concern globally but facing increased fishing pressure in Britain and Europe where it has been listed as Vulnerable. It's especially under pressure in the Mediterranean where it is classified as Near Threatened. It is farmed commercially in Spain and some other parts of Europe.

Why is this species a priority in Northern Ireland?

• Criterion 1: Internationally listed species.
• Criterion 2: Decline based on available data and expert judgement.

Threats: They are at risk from overfishing. There is a high demand for this species in some areas driving intensive commercial fishing. This is compounded by the fact they are relatively slow to mature making them vulnerable to overexploitation. Being a benthic species they are also at threat from bottom fishing methods both from capture and habitat destruction. Juveniles are frequently caught as bycatch in trawl nets and discarded. It is currently a non-quota species in Northern Ireland.

Action: Records of new sites for this species, with details of habitat and population are always valuable. Observations with a photograph can be recorded using iNaturalist, find the MBDP-NI iNaturalist project here.

Alternatively, records can be sent to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257, e-mail cedar.records@nationalmuseumsni.org, or via the online portal.

Objectives:

• Develop a catch quota for turbot as currently this is not regulated.
• Assess population levels and fishing effort in a Northern Irish context to better inform conservation measures.
• Monitor populations and maintain at current levels.
• Create areas free from harmful bottom fishing methods to allow this (and many other species) a chance to recover and repopulate.

Conservation:

• Listed as Vulnerable on European Red List.

Distribution Map from NBN: Psetta maxima at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Psetta maxima at iNaturalist World Species Observations database.

WoRMS: Psetta maxima at World Register of Marine Species. Accepted name: Scophthalmus maximus (Linnaeus, 1758). AphiaID: 127149.

Classification: Biota; Animalia; Chordata; Vertebrata; Gnathostomata; Osteichthyes; Actinopterygii; Actinopteri; Teleostei; Pleuronectiformes; Pleuronectoidei; Scophthalmidae; Psetta

Picton, B.E., Keatley, L. & Morrow, C.C. (2026). Psetta maxima. (Linnaeus, 1758). [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=ZG8590. Accessed on 2026-09-13