These silvery fish are distantly related to trout and salmon. They are small shoaling fish that are found in relatively shallow coastal and estuarine waters throughout Western Europe. In some parts of Europe smelt are harvested for food as well as for making fish-meal. Very little is known about the occurrence and biology of the smelt in Northern Ireland but it has been investigated to a limited extent in the Republic of Ireland. Much of the relevant information on their biology comes from studies on the River Cree (Wigtownshire, Scotland).

In brief

• Smelt have been recorded in Lough Foyle, Larne Lough and Belfast Lough.
• Found in shallow coastal and estuarine waters.
• Spawns in the lower reaches of rivers around the tidal limit.
• Can be seen in lower reaches of rivers and estuaries during spawning, February to March.
• Current status in Northern Ireland is unknown, but it is likely to be in decline.
• Threatened by water pollution, dredging and habitat change.
• More detailed study of its distribution, occurrence and biology in Northern Ireland is required.

Species description: A slender silvery fish with a large mouth, rarely exceeding 20 cm in length but can grow up to 35 cm, with a very distinctive cucumber smell when fresh. Fishermen call smelt ‘stinkers’ due to the strong smell left by dead fish in boats and nets. When fresh, the back is a light olive green colour and the sides often have a pronounced silvery strip from head to tail. As with its relatives the salmonids, smelt possess a small fleshy dorsal fin just in front of the tail (adipose fin).

Life cycle: Smelt are anadromous (freshwater-sea migratory) although, in Scandinavia, purely freshwater populations exist. Adults live in estuarine or coastal waters and come into the lower freshwater or brackish reaches of rivers to spawn, normally in February and March. The eggs are often deposited in moss on walls and rocks above, or just around, the tidal limit of the river. After hatching the larvae drift passively downstream and feed on animal plankton. Larger individuals feed on crustaceans and small fish. They can live for up to 8 years.

Similar species: The sand smelt, an unrelated marine species, and the argentine are superficially similar but there are no other similar species that enter freshwater. Shoals of descending salmon and trout smolts might also be confused with smelt. However, smelt can be distinguished by the large gape of its mouth with the jaws extending well past the level of the rear edge of the eye and its relatively large scales.

How to see this species: Smelt are regularly caught in the Foyle estuary during salmon netting. They have previously been recorded from the water-intake screens at Kilroot (Belfast Lough), Ballylumford (Larne Lough) and Coolkeeragh (Lough Foyle) power stations. They can be seen in lower reaches of rivers and estuaries during spawning, February to March.

Current status: Unknown in Northern Irish waters, however it is likely to be in decline. Smelt have been recorded from Belfast, Larne and Foyle loughs but few recent records are available other than for the Foyle where it is likely that spawning still occurs. The species has declined in other parts of Western Europe and it is therefore likely that it has declined in Northern Ireland. The current status of smelt in the above loughs, Carlingford Lough, Strangford Lough, and main river estuaries should be determined. The importance of smelt as a food for other fish (for example, sea trout) and for birds also requires investigation.

Why is this species a priority in Northern Ireland?

• Criterion 1: Internationally listed species.

Threats: As smelt are short-lived they are very vulnerable to high mortality in a single cohort as a result of river and estuarine pollution. River dredging and other habitat changes can damage spawning areas and the erection of regulation barriers at the tidal limit can prevent smelt ascending to these areas. Collecting of smelt for use as fishing-bait is a potential threat elsewhere but it is not known if this occurs 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:

• Maintain the number of viable populations of the species
• Establish appropriate management on appropriate historic sites ensuring that river management plans take account of the needs of smelt
• The current distribution, abundance and biology in Northern Ireland waters needs to be determined
• Identify potential spawning sites based on requirements elsewhere.

Conservation:

• Listed on Irish and Global Red List as Least Concern.
• Protected under Foyle Fisheries Act (Northern Ireland).

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

iNaturalist: Osmerus eperlanus at iNaturalist World Species Observations database.

WoRMS: Osmerus eperlanus at World Register of Marine Species. Accepted name: Osmerus eperlanus (Linnaeus, 1758). AphiaID: 126736.

Classification: Biota; Animalia; Chordata; Vertebrata; Gnathostomata; Osteichthyes; Actinopterygii; Actinopteri; Teleostei; Osmeriformes; Osmeroidei; Osmeridae; Osmerus

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Adapted from text by Professor Andrew Ferguson (2026). Osmerus eperlanus. (Linnaeus, 1758). [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=ZG830. Accessed on 2026-09-13