Invasive alien species (IAS) are one of the major drivers of change that can negatively affect biodiversity, ecosystem functions and services and human health; islands are particularly vulnerable to biological invasions. Horizon scanning can lead to Electronic supplementary material The online version of this article (

Recent years have seen a global and rapid resurgence of fungal diseases with direct impact on biodiversity and local extinctions of amphibian, coral, or bat populations. Despite similar evidence of population extinction in European fish populations and the associated risk of food aquaculture due to the emerging rosette agent Sphaerothecum destruens, an emerging infectious eukaryotic intracellular pathogen on the fungal–animal boundary, our understanding of current threats remained limited. Long-term monitoring of population decline for the 8-year post-introduction of the fungal pathogen was coupled with seasonal molecular analyses of the 18S rDNA and histological work of native fish species organs. A phylogenetic relationship between the existing EU and US strains using the ribosomal internal transcribed spacer sequences was also carried out. Here, we provide evidence that this emerging parasite has now been introduced via Pseudorasbora parva to sea bass farms, an industry that represents over 400 M€ annually in a Mediterranean region that is already economically vulnerable. We also provide for the first time evidence linking S. destruens to disease and severe declines in International Union for Conservation of Nature threatened European endemic freshwater fishes (i.e. 80% to 90 % mortalities). Our findings are thus of major economic and conservation importance.

The underlying mechanisms responsible for ecological plasticity and consequent invasive character of non‐native freshwater fish species, variations in growth and life history traits in gibel carp Carassius gibelio (Bloch) were compared in natural and artificial water bodies of Turkey. Females significantly outnumbered males in all natural and most artificial waters. Discriminate function analysis differentiated gibel populations into three separate groups (natural lakes, artificial water bodies and running waters), with significant differences among separated groups in growth index, standard length and age at maturity, relative fecundity and gonado‐somatic index, but not in egg diameter and both generalised and relative condition. Growth features (e.g. growth index and relative condition) and reproductive features (e.g. relative and absolute fecundity) positively correlated with water body area. No correlations were found for any growth or life history trait with depth, latitude and altitude. With the exception of smaller size at maturity, all traits were higher in populations from artificial water bodies than those inhabiting running waters, suggesting gibel carp is required to exert more reproductive effort to invade natural ecosystems than artificial waters.

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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. K E Y W O R D SAnatolia, FISK, introduced species, non-indigenous, non-native, Thrace

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Summary Length–weight relationships were calculated for nine freshwater fish species belonging to two families using 1020 specimens from 15 water sources in the western part of Anatolia, Turkey. This study is the first reference on length–parameters for these species, eight of which are endemic, and with new maximum length records for three of the species.