Softmouth trout

What it is

This fish belongs to the salmon family. It has a distinctively long snout and a small, fleshy mouth. Its body is deep with relatively large scales. The colour varies among populations but is usually green with red and black spots. Unlike the brown trout found in the same region, it lacks vertical stripes on its sides.

Where it lives

The species lives in four main river systems flowing into the Adriatic Sea. These include the Neretva-Vrljika network, the Jadro, and the Morača-Zeta system. It may have once lived in the Krka river near Knin, but it is likely gone from there now. In the 1960s, humans moved some fish from the Jadro to the nearby Žrnovnica river. The Vrljika river is unique because it sinks underground, separating its fish population from the main Neretva group.

How it lives

It is an obligatory freshwater fish, meaning it does not migrate to the sea. It prefers rivers with abundant water and wide beds. While it shares habitats with brown trout, the two species have different spawning times. This timing difference limits natural mixing. However, they do live side by side in the same rivers. Hybrids, known locally as kosor, appear occasionally in the Neretva.

Breeding and life cycle

Spawning takes place in early spring. The reproductive cycles of this trout and the brown trout overlap only slightly every few years. This slight overlap allows for rare natural hybridisation events. Experimental studies have confirmed that these two species can breed together. The separation of populations, such as in the Vrljika, likely occurred when ancestral groups were split by geological changes.

Fish and people

Anglers value this trout as a game fish in the Western Balkans. It is a target for sport fishing in its native rivers. Local communities recognise hybrids between this species and brown trout. The fish holds ecological importance in the karst river systems where it resides. Conservation efforts focus on protecting its remaining habitats from human interference.

Status and threats

Dams pose a major threat to its survival by altering river flow. Hybridisation with introduced brown trout reduces genetic purity. Overfishing also pressures wild populations. The Krka population is presumed extinct. Habitat fragmentation separates groups, such as those in the Vrljika and Neretva, making them vulnerable to local extinction.

Questions people ask about Softmouth trout

Good reading and sources

• Salmo obtusirostris on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data