Fish introductions can result in their establishment in the wild, with invasion risk assessments identifying those non‐native species with a high probability of developing invasive populations. The North American fathead minnow Pimephales promelas was imported to Europe for decades for both ornamental and scientific (toxicology research) purposes. In North America, the fathead minnow has been introduced widely into areas outsi...

Although the European Water Framework Directive (WFD) does not refer explicitly to alien species (AS), it is clear that invasive AS (IAS) are considered a pressure on WFD water bodies. This article discusses the results of a questionnaire sent to all EU Member States, demonstrating considerable variability in the way that AS data are used in implementing the WFD. Responses were received from 18 countries. Most countries define...

Invasive non‐native species (NNS) are internationally recognized as posing a serious threat to global biodiversity, economies and human health. The identification of invasive NNS is already established, those that may arrive in the future, their vectors and pathways of introduction and spread, and hotspots of invasion are important for a targeted approach to managing introductions and impacts at local, regional and global scal...

The European Non‐native Species in Aquaculture Risk Analysis Scheme (ENSARS) was used to assess one of the most popular aquaculture species in the world, the striped catfish Pangasianodon hypophthalmus (Sauvage, 1878), in two locations of southern Anatolia (Turkey). The overall mean risk score generated for P. hypophthalmus by the ENSARS Organism module (which assesses the risks of introduction, establishment, dispersal and im...

The European Union ( EU ) has recently published its first list of invasive alien species ( IAS ) of EU concern to which current legislation must apply. The list comprises species known to pose great threats to biodiversity and needs to be maintained and updated. Horizon scanning is seen as critical to identify the most threatening potential IAS that do not yet occur in Europe to be subsequently risk assessed for future listin...

The European Non‐native Species in Aquaculture Risk Analysis Scheme ( ENSARS ) was developed in response to European ‘Council Regulation No. 708/2007 of 11 June 2007 concerning use of alien and locally absent species in aquaculture’ to provide protocols for identifying and evaluating the potential risks of using non‐native species in aquaculture. ENSARS is modular in structure and adapted from non‐native species risk assessmen...

Developed for carrying out risk assessments under the European Commission ( EC ) Council Regulation No 708/2007 concerning the use of alien and locally absent species in aquaculture ( ASR ), the European Non‐native Species in Aquaculture Risk Assessment Scheme ( ENSARS ) is briefly summarised, and the ‘Organism’ module is applied to the 24 species listed in ASR 's Annex IV . Four other ENSARS modules (Infectious Agent, Facilit...

A high level of freshwater fish endemism in the Balkans Region emphasizes the need for non-native species risk assessments to inform management and control measures, with pre-screening tools, such as the Fish Invasiveness Screening Kit (FISK) providing a useful first step. Applied to 43 non-native and translocated freshwater fishes in four Balkan countries, FISK reliably discriminated between invasive and non-invasive species,...

External morphology in black bullhead Ameiurus melas , a fish species considered to have high invasive potential, was studied in its four non‐native European populations (British, French, Italian and Slovak). The aim of this study was to examine this species' variability in external morphology, including ontogenetic context, and to evaluate its invasive potential. Specimens from all non‐native populations reached smaller body...

Gibel carp, Carassius gibelio (Bloch), impacts on native fish species have been reported but little studied despite a long history of introductions in Europe. This species is able to reproduce gynogenetically, which involves the use of sperm from males of other species to activate egg development, so reproductive competition is a likely but virtually unstudied impact of gibel carp on native fishes. This study evaluates the imp...

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 populatio...

Scale samples from crucian carp, Carassius carassius (L.), collected over a 10‐year period from a population in an ornamental pond were used to examine patterns in growth as a function of environmental factors, including water temperatures. Back‐calculated standard lengths (SL) at age differed between year classes in most cases. Annual SL increments were related to temperature and age using a non‐linear growth model. Growth de...

To assess the colonization success of pumpkinseed Lepomis gibbosus on the Iberian Peninsula, life‐history attributes of pumpkinseed populations from Spanish water bodies were compared to populations in the northern and southern parts of its native range, as well as to those of English water bodies where introduced populations have shown minimal natural range expansion. Discriminate function analysis using five population chara...