Introduction and distribution of alien freshwater fishes on the island of Sardinia (Italy): an assessment on the basis of existing data sources

Data on the occurrence and distribution of alien freshwater fishes in Sardinia are provided based on historical data and recent reports. A total of 14 introduced fish species are established in Sardinian fresh waters. These species comprise members of the Cyprinidae (carp, Cyprinus carpio; tench, Tinca tinca; goldfish, Carassius auratus; rudd, Scardinius erythrophthalmus; bleak, Alburnus alburnus alborella), Centrarchidae (pumpkinseed, Lepomis gibbosus; largemouth bass, Micropterus salmoides), Salmonidae (rainbow trout, Oncorhynchus mykiss; brown trout, Salmo trutta), Cobitidae (spined loach, Cobitis taenia), Ictaluridae (black bullhead, Ameiurus melas), Percidae (European perch, Perca fluviatilis), and Poeciliidae (mosquitofish, Gambusia holbrooki). The species most recently introduced into Sardinia is the topmouth gudgeon, Pseudorasbora parva (Cyprinidae). The majority of alien fishes documented here match those that have already established self-maintaining populations elsewhere in Mediterranean-type eco-regions. Since the late nineteenth century, fish identified as potential sources of food have been introduced for aquaculture and stock enhancement purposes. Other introductions have subsequently occurred for the purposes of biological control, ornamental use or sport fishing activities. Some species are notably widespread and common (e.g. mosquitofish and tench), whereas the presence of others seems to be more restricted and may still be confined to a few hydrographic regions (e.g. bleak, rudd, pumpkinseed and topmouth gudgeon)