10 20 40 60 cm
mittakaava > 60 cm
Gösta Sundman: Suomen Kalat (Kansalliskirjasto, The National Library of Finland), Lauri Urho, Petri Savola (Uudenmaan ympäristökeskus), Jouko Lehmuskallio. All rights reserved.
- Family: Freshwater eels – Anguillidae
- Other eel-like species: brook lamprey, river lamprey, rock gunnel, snake blenny, viviparous blenny
- Size: Female 50-100 cm, 0.5-2 kg, max. 3-4 kg. Male smaller, usually under 50 cm.
- Appearance: Elongated cylindrical snake-like body compressed laterally towards the tail. Long dorsal fin continuous with caudal and anal fins. No caudal fin as such. Pelvic fins also absent. Lower jaw longer and protruding. Gill openings small and restricted to sides. Scales small and elongated, almost invisible to the naked eye. Eyes become enlarged on migration to the sea.
- Colouring: Immature (yellow) eels are dark olive green with a yellowish belly. As they prepare for their spawning migration the skin on the back becomes blackish brown, the belly almost white, and the sides acquire a metallic sheen.
- Reproduction: In terms of its reproductive cycle, the eel is perhaps the strangest and most mysterious of Finland’s fishes. At a time when even the human genome has yielded to science, it is remarkable that the eel’s spawning ritual is still not completely understood. Having left freshwater, adult eels migrate to the Sargasso Sea in the western Atlantic, where they disappear into the depths. It is from here that, drifting with the Gulf Stream, the tiny leaf-like eel larvae (leptocephalus) begin the long homeward journey. As they near their home coasts they lose their transparency, acquire pigmentation and finally enter estuaries as elvers. These tiny eels run rivers seeking freshwater lakes inland. Today, dams and other constructions prevent many eels from reaching their destination, and the planting of immature forms and elvers from the sea into freshwater is the only way to maintain inland waterway stocks.
- Food: Bottom invertebrates and small fish.
- Distribution and habitat: All eels found in inland waters in southern Finland have been introduced by stocking. Although some natural migration may take place, this seems to have declined considerably. Eels thrive in many waters but seem to favour warm, shallow water rich in food. Active mainly at night, when it seeks its prey. Spends daylight hours and probably the entire winter lying hidden on the bottom.
- Endangerment: Critically endangered (also globally).
Eels have a reputation for being powerful, resilient fish, qualities they need to complete the long and arduous migration from freshwater to their Atlantic spawning grounds. Muscular and slippery, eels are difficult to grip. To escape from the boat an eel only has to get its tail over the side. Eels will writhe around even after being gutted and decapitated! Can survive on dry land for long periods thanks to the small gill openings.