Salmo obtusirostris, also known as the Adriatic trout, Adriatic salmon, and softmouth trout, is a species of salmonid fish endemic to the rivers of Western Balkans in southeastern Europe. The scientific name has changed several times through history; synonyms include Thymallus microlepis, Salmothymus obtusirostris and Salar obtusirostris.
This species spawns in the early spring and is an obligatory freshwater fish. They are an important game fish.
Salmo obtusirostris is found naturally in four drainages of the Adriatic Sea, in Croatia, Bosnia and Herzegovina and Montenegro: the Neretva-Vrljika system, the Jadro, the Morača-Zeta system, and possibly the Krka river drainage around Knin although it is presumed extinct for some time now.
In addition, sometimes during 1960's, it has been introduced from the Jadro river to the nearby Žrnovnica river, both being small karst, single river drainages, of very short course, in vicinity of Split.
Although the Vrljika belongs to the Neretva River drainage it's a sinking river, divided in several on surface and underground segments, hence separated from the Neretva River in significant manner regarding softmouth trout populations. However, the Vrljika softmouth trout is apparently most similar to the Neretva's subspecies, while some autapomorphies exist in the Vrljika population. The Vrljika softmouth trout appears to have originated from a vicariance that split a common ancestral population into large (Neretva) and small (Vrljika) fragmented populations.
The different populations are sometimes classified into subspecies:
Salmo obtusirostris oxyrhynchus: Neretva and its tributaries the Buna, the Bregava, the Rama, the Trebižat in Bosnia and Herzegovina and the Vrljika within both Bosnia and Herzegovina and Croatia
Salmo obtusirostris salonitana: the Jadro River and the Žrnovnica River in Croatia
Salmo obtusirostris krkensis: the Krka river in Croatia
Salmo obtusirostris zetensis: the Zeta River and the Morača River in Montenegro.
