Stocking of alien species of fishing interest European regulatory framework, dates of first introduction in Italy, ecological impacts

The Habitats Directive of the European Union requires Member States to regulate the introduction of alien species into their territory, avoiding any adverse impact on natural habitats or native fauna and flora. Italy has implemented this obligation by adopting a general prohibition on the introduction of non-native species into the environment. The Ministry of the Environment (MASE) may, however, authorize the introduction of alien species if there is no prejudice to habitats and native species. As part of the work carried out by the Research and Evaluation Unit established to analyze the conditions for applying this ban on fish species, ISPRA was asked to conduct further studies on 1) the regulatory framework in other European countries regarding the introduction of alien fish, 2) the regional distribution and year of first introduction of key alien species of fishing interest, 3) the presence of naturalized populations of these species and 4) the impacts of these species on native species and ecosystems. The evaluations focused on Coregonus lavaretus, Salvelinus umbla, Oncorhynchus mykiss, and Salmo trutta. A comparative analysis of how other European countries implemented the Habitats Directive revealed a universal ban on the release of alien species into the wild. Furthermore, 84% of the countries have adopted derogation systems for non-native species introductions. The assessment of the dates of the first introductions in Italy showed that most alien fish species were introduced in the second half of the nineteenth century, leading to the establishment of naturalized populations of all fish species of fishing interest in many basins across the country. Fifty-one native species protected by regulations are susceptible to significant impacts from Oncorhynchus mykiss and Salmo trutta. Over 60% of these native species are in an unfavourable conservation status, as documented in the latest report submitted by Italy to the European Commission.