Past, present and future of Lake Orta fish community

Lake Orta, one of the largest lake in Italy, underwent dramatic changes in its fish community during the last two hundred years mainly due to species introductions and chemical pollution which markedly shaped the fish assemblages. Although quantitative data from standardized monitoring are lacking for the past, literature informations indicate an important role of typical pelagic fish species in commercial harvest, especially after the introduction of the European whitefish Coregonus lavaretus at the beginning of the XX century. Indeed European whitefish, landlocked shad (Alosa agone), bleak (Alburnus alborella) and trout (Salmo trutta) were the most important part of the commercial catches together with the littoral perch (Perca fluviatilis). Since the 1930s however, the fish community soon started to be affected by chemical pollution and in a few years the fish community was almost completely destroyed. In the 1990s soon after the liming and the actions addressed to the reintroduction of fish species coordinated by the Province of Novara and the "Istituto italiano di Idrobiologia" of the CNR, Lake Orta fish community slightly recovered. At present, standardize monitoring an overwhelming abundance of perch but, still, the total absence of "typical" pelagic species such as the native landlocked shad and the European whitefish. Additionally, new native species, such as the roach and the pikeperch, became significantly important. In the light of this scenario, Lake Orta appears today as a very delicate environment where the management of fish community need a strong scientific support to be effective.