Adriatic salmon  (Salmo obtusirostris)

The Adriatic salmon is classified as Endangered (EN) on the IUCN Red List (1).

The Adriatic salmon (Salmo obtusirostris) differs from most other salmon species by not spending any period of time in the ocean. Instead, the Adriatic salmon is a true freshwater fish that spends its entire life in rivers (2). The Adriatic salmon has a long, slender body and pointed snout, which minimises drag in the water, making it an efficient swimmer (2). The upperparts are greenish-brown, the belly is yellowish-brown, and the sides are patterned with numerous red and black spots (2). The large tail fin is unforked or just slightly forked (2).

Although similar in appearance to the brown trout (Salmo trutta), the Adriatic salmon can be distinguished by a thicker upper jaw and by the mouth, which is positioned lower on the face (2).

The Adriatic salmon occurs in Croatia, Bosnia-Herzegovina and Montenegro, where it is restricted to a few rivers in the Krka, Jardo, Nereveka and Zeta river basins. It has also recently been introduced into the Zrnornica River (1). Although it does not, like many other salmon, migrate into the ocean, it does migrate up and down the rivers it inhabits (2).

This freshwater fish inhabits cold streams and small rivers at high altitudes, where it favours deep, undisturbed places (3).

The Adriatic salmon, which usually occurs in shoals (3), feeds on small fish, insects, and other small aquatic invertebrates (2).

It spawns in April or May (3). A small number of the population reach maturity and begin to spawn in their third year, but the majority spawn in their fourth year of life (4).

The Adriatic salmon faces a number of threats, including overfishing for sport and for food, as well as habitat destruction and competition with introduced species (1).

Accidentally introduced trout (often escapees from fish farms) can be aggressive predators, which outcompete the Adriatic salmon for food and suitable areas of habitat (2). Hybridisation with these invasive trout is also a concern (1).

This already endangered species is further threatened by the destruction of its habitat (1). Dams, created for hydroelectric power, block the movement of the Adriatic salmon up and down rivers as it searches for food or suitable areas in which to spawn (2).

Climate change also poses a long-term threat to the Adriatic salmon (1), as an increase in global temperatures is predicted to result in a decrease in freshwater in the Mediterranean basin region (6).

There are currently no known conservation measures in place for the Adriatic salmon (1) (5). It has been recommended that a number of key rivers in which this species occurs should be given full protection and guarded from any habitat alteration (5).

Further research into the ecology and biology of the Adriatic salmon is also required, which will help inform any future conservation measures for this endangered fish (5). 

Learn more about how climate change will impact the Mediterranean basin:

• WWF: Climate Change in Mediterranean Basin:
  http://wwf.panda.org/about_our_earth/aboutcc/problems/rising_temperatures/hotspot_map/mediterranean_basin.cfm