Identification of potentially invasive freshwater fishes, including translocated species, in Turkey using the Aquatic Species Invasiveness Screening Kit (AS-ISK)

Screening tools are being increasingly used to identify more effectively non-native species that pose an elevated risk of being invasive. Of the available decision-support tools, the Fish Invasiveness Screening Kit (FISK) has been widely used, but has recently been replaced by a generic screening tool, the Aquatic Species Invasiveness Screening Kit (AS-ISK), which is applicable to any aquatic species and complies with the minimum requirements for risk tools under the new EC alien invasive species Regulation. With its unique zoogeography and rich native fauna, Turkey is highly susceptible to non-native species’ introductions and translocations. In order to inform non-native species policy and management regarding fishes in Turkey, AS-ISK was used to re-assess species previously screened using FISK and to assess additional non-native and translocated fish species. In this first calibration study of AS-ISK for Turkey, a basic score threshold of 28 was achieved, which reliably distinguished between potentially invasive (high risk) and potentially non-invasive (medium to low risk) fishes. Of the 64 species assessed, only one was ranked as ‘low risk’, 40 were categorised as ‘medium risk’, and the remaining 23 as ‘high risk’ of which five were translocated. Non-native species currently not present in Turkey, but that pose a high risk of being invasive, were Ameiurus melas, Ameiurus nebulosus, Hemiculter leucisculus, Hypophthalmichthys molitrix, Micropterus salmoides, Perccottus glenii, Pimephales promelas; whereas, the highest scoring translocated species were Cyprinus carpio, Esox lucius and Silurus glanis. When the potential effects of climate change on the assessments were considered, risk scores increased for some (sub)tropical fishes of which two are translocated species.