Huchen
The huchen or Danube salmon (Hucho hucho) is the largest freshwater fish in the salmon family in Slovenia. Adult huchen reaches up to 1.35 m in length and more than 30 kg in weight. It has an elongated body with a large head. The huchen is a typical predator with slender body, large head and a large mouth with strong teeth. The back is a green-brown to grey-brown colour and patterned with numerous dark spots, the sides are reddish-grey with a copper-coloured gloss, and the belly is silvery-white.
The huchen is endemic to the Danube basin, and it has also been introduced in other basins. In Slovenia is present in the following rivers: Sava Bohinjka, Sava, Ljubljanica, Sora, Mirna, Drava, Krka, Kolpa and their tributaries. In the past, it was present in Mura, but in the 60th years completely disappeared. During spawning sexually mature specimens travel to upriver into smaller tributaries to spawn in pairs on the gravel floor. The photo shows the huchens spawning in the confluence of the rivers Small and Large Ljubljanica. Smaller fish feed on the larvae of water insects; the larger individuals are predators of other species of fish.
Threats
The hucher is among trouts the most sensitive to changes in water courses. Species is threatened by water pollution, management and regulation of watercourses and placement of hydroelectric power plants, which disconnects the connection between fish populations and prevent the migration of fishes upstream. A large problem is the impoundment of the upper parts of rivers where huchen was once common. Due to a series of interventions in the trout band and the consequent deterioration of the living conditions the huchen become more common in the grayling and barbel band. Currently in Slovenia the huchen has a status of endangered species (Red List), which indicates the species whose survival in the Republic of Slovenia is unlikely if the factors of threats will continue (Rules on the inclusion of endangered plant and animal species in the Red List).
