Fauna and flora in Slovakia – the danube salmon

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The Danube salmon or huchen (Hucho hucho) is endemic to the Danube basin and is the only native salmonid species in Slovakia. This predatory fish, the largest European salmonid, can grow up to around 150 cm in length, weigh more than 50 kg, and have a lifespan exceeding 15 years. Its body is torpedo-shaped, with a large head and a terminal mouth extending beyond the back edge of the eye. An adipose fin is located between the caudal and dorsal fins. Coloration ranges from grey-green to reddish-brown, with dark spots. Juveniles are lighter in colour with dark stripes along the sides of the body. The Danube salmon inhabits fast-flowing submontane rivers with cold, well-oxygenated water. When young, it feeds on invertebrates and smaller fish; as an adult, its diet consists mostly of fish. Spawning occurs between March and April, following upstream migration. The female uses her tail to make a shallow depression (redd) in the gravel riverbed, where the eggs are laid and fertilised. Juveniles remain in shallower currents or smaller tributaries, while older individuals occupy deeper river sections. In Slovakia, the Danube salmon occurs in the foothill reaches of the Hron, Váh, Turiec, and Orava rivers, as well as in the Danube River itself, and has been introduced into the Poprad and the Dunajec rivers.
The Danube salmon is an endangered species of European conservation importance. It is threatened primarily by river impoundment and resulting migration barriers, as well as by water pollution and other environmental changes. Fishing is permitted only under strict conditions and requires a special licence.