Softmouth trout - Salmo obtusirostris

The softmouth trout is endemic to the Adriatic river system of the western Balkans and was first described from the Rivers Zrmanja, Jadro and Vrljika as Salar obtusirostris (Heckel, 1851). Subsequently, morphological differences characteristic for different softmouth trout populations gave rise to the description of three additional putative subspecies: Salmo obtusirostris oxyrhynchus (Steindachner, 1882) from the River Neretva, Bosnia and Herzegovina, Salmo obtusirostris salonitana (Karaman, 1927) from the river Jadro, Croatia, and Salmo obtusirostris krkensis (Karaman, 1927) from the River Krka, Croatia. Softmouth trout-like salmonids from the River Zeta, Montenegro are also sometimes regarded as a subspecies of Salmo obtusirostris as Salmo obtusirostris zetensis (Hadžišče, 1961).

The softmouth trout is characterized by its striking similarity in appearance to both trout and grayling. Its most peculiar morphological characteristics are an elongated snout, a small and flashy mouth, relatively large scales and high body depth. It is a spring spawning obligatory freshwater fish.

Historically softmouth trout has been considered an archaic salmonid. Owing to its morphological peculiarities, its taxonomic position was rearranged on many occasions as obvious from a number of different scientific names such as Thymallus microlepis (Steindachner, 1874), Salmothymus obtusirostris (Berg, 1908) and Salmo obtusirostris (Behnke, 1968). Recent comparative morphological studies place the softmouth trout as close to or even within Salmo (Svetovidov, 1975; Sanford, 2000) with the notable exception of Stearley and Smith (1993), who placed it into Salmothymus. More recently, our own genetic data (Snoj et al., 2002), as well as previous studies place softmouth trout clearly within the genus Salmo, appearing, together with Belvica from Lake Ohrid, as phylogenetic intermediates between brown trout and Atlantic salmon.

Berg L.S. 1908. Annuaire du Musée Zoologique de l’Academie Imperiale des Sciences de St. Petersbourg 12: 500-514.
Hadžišče S. 1961. Internationale Vereinigung für theoretische und angewandte Limnologie Verhandlungen 14: 785-791.
Heckel J.J. 1851. Akad. Wiss. Wien 347-390.
Karaman S. 1927. Bulletein de la Societé Scientifique de Skoplje 2: 253-268.
Sanford C.P. 2000. Theses Zoologicae, 33, 1-264.
Stearley R.F., Smith GR. 1993. Transections of the American Fisheries Society, 122: 1-33.
Steindachner F. 1874. Anz. Akad. Wiss. Wien, 171-172.
Steindachner F. 1882. Sitzungsber. Akad. Wiss. Wien, 61-82.
Svetovidov A. 1975. Zoologicheskii Zhurnal, 54, 1174-1190.
Snoj, A., Melkič, E., Sušnik, S. 2002. Biol. J. Linn. Soc., 77, 3, 399-411.