Native fish species under pressure in the Engadine and Poschiavo
From 2010 to 2014, a total of 26 prealpine lakes were studied as part of Projet Lac, with over 60 fish species being recorded. In 2012, in cooperation with Canton Graubünden's Hunting and Fishery Office, surveys were carried out on Lake Sils in the Engadine and Lago di Poschiavo. The results, now available, show that both of these lakes harbour a commercially attractive salmonid community. However, both lakes' historical diversity has been significantly affected by the introduction of fish species from several other catchments – in particular, the Arctic char (Salvelinus alpinus), Canadian lake trout (Salvelinus namaycush) and brown trout (Salmo trutta). Genetic analyses indicate that the non‑native fish have interbred with indigenous species, leading to substantial losses of biodiversity. The distinctiveness of the original Lake Poschiavo trout, for example, has largely been lost. In Lake Sils, however, an indigenous population of Black Sea trout (Salmo labrax) seems to have...