Salmonid Fish Species: Opportunities for Sustainable Use under Multiple Pressures and Current Climatic Change

Abstract

The chapter covers the current status of salmonid fishes in the Western Balkans in the Adriatic, Aegean, and Danube drainage basins on the territories of Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, and North Macedonia. Salmonids (family Salmonidae) are freshwater and anadromous fish native to the northern hemisphere. The family is composed of three subfamilies: Salmoninae, Thymallinae, and Coregoninae. Only species of the families Salmoninae and Thymallinae occur naturally in the inland waters of the Western Balkans; these species do not normally migrate to the sea in this area. Of the Salmoninae, in addition to the Danube salmon (Hucho hucho), a large number of trout species (Salmo spp.) can be found here, which is hard to find anywhere else in their distribution range. Two species of the Thymallinae are represented, the European grayling (Thymallus thymallus), which has its southernmost distribution limit in this region, and the Adriatic grayling (Thymallus aeliani) from the northern Adriatic basin. In addition, exotic salmonid species—e.g. rainbow trout (Oncorhynchus mykiss), brook char (Salvelinus fontinalis), and lake char (Salvelinus umbla)—have been introduced and naturalized in a number of water bodies.

In the inland waters of the Western Balkans, salmonids play an important economic and social role in both commercial and recreational fisheries. Unfortunately, this has long since led to the fact that many of the stocks have been severely depleted, in some cases almost destroyed, by the pressure of fishing. To counteract this, stocking with hatchery fish is common in many places. However, stocking with non-native brown trout has often resulted in genetic introgression into the autochthonous populations of Salmo trouts and loss of their genetic integrity. Other threats to the survival of salmonid populations include water pollution from agriculture and sewage, as well as dam construction, which has particularly increased recently. The increased demand for drinking water as a result of the growing tourism industry poses an additional threat to aquatic ecosystems and could be exacerbated by climate change.