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. There are a light olive green colour with a pronounced silvery strip running down their side 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).

Habitat: 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.

Distribution: 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.

Similar Species: The sand smelt Atherina presbyter, an unrelated marine species, and the argentine (Argentina silus) 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.

Key Identification Features:

• Slender, silvery fish with large mouth
• Distinctive cucumber smell
• Light olive green with silvery strip down side
• Large mouth gape
• Relatively large scales

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

iNaturalist: Osmerus eperlanus at iNaturalist World Species Observations database.

GBIF data for Osmerus eperlanus

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