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...

The bleak Alburnus alburnus is a medium body-size leuciscid fish that is naturally distributed across central European and western Asian fresh waters. However, during the last two decades A. alburnus has been widely introduced elsewhere in Europe and in northern Africa, mostly as a forage species for game fishes. Given its relatively recent history of invasion in non-native Eurasian waters, where it can become highly abundant,...

This review provides a meta‐analytical assessment of the global patterns and clines in the growth of Cyprinus carpio as measured by length‐at‐age ( L t ) or von Bertalanffy growth function ( VBGF ) parameters, mass–length relationship ( W–L t ) and condition factor, based on literature data. In total, 284 studies were retrieved spanning 91 years of research and carried out on 381 waterbodies–locations in 50 countries in all fi...

This paper presents the first phase in the development and validation of a simple and reliable environmental (e) DNA method using conventional PCR to detect four species of non‐native freshwater fish: pumpkinseed Lepomis gibbosus , sunbleak Leucaspius delineatus , fathead minnow Pimephales promelas and topmouth gudgeon Pseudorasbora parva . The efficacy of the approach was demonstrated in indoor tank (44 l) trials in which all...

The Fish Invasiveness Screening Kit ( FISK ) version 2 was used to assess the invasiveness potential of 40 introduced and translocated freshwater fish species to Croatia and Slovenia. Based on a priori classification of invasiveness, receiver operating characteristic analysis of FISK scores from two independent assessors resulted in a statistically significant calibration threshold of 11.75. This indicated that FISK was able t...

The invasion of non‐indigenous freshwater fish species is one of the most important threats to aquatic biodiversity. Similar to other Mediterranean countries, Greece is considered a hot spot for freshwater biodiversity, with many range‐restricted endemics of high conservation concern. The aim of this study was to undertake a risk screening assessment to evaluate the invasive potential of non‐native, translocated and traded aqu...

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...

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...

The movement of barbel Barbus barbus free embryos in the interstitial zone and the timing of larval emergence were studied for 12 days in an artificial stream. After egg fertilization (day 1), hatching occurred on day 6, downstream interstitial movements of free embryos on day 9 and emergence and downstream movement of all larvae on day 12, with density of free embryos decreasing as day of emergence approached. The results sug...

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...

The extent and causes of crucian carp Carassius carassius decline were assessed during an initial study of c. 25 ponds in north Norfolk, eastern England, U.K., which was then replicated (a validation study) on another c. 25 ponds in an adjacent area. Of these ponds, c. 40 are known to have contained C. carassius during the 1970s–1980s. In the initial and validation studies, C. carassius were found in only 11 of these ponds, yi...

Heated and ambient temperature experimental ponds were used to examine competition between introduced pumpkinseed Lepomis gibbosus and native perch Perca fluviatilis in England, U.K., and how these interactions are likely to change under climate warming conditions. Results from three sets of two‐week experiments indicated that in both species and in all sets, growth was faster in heated than in ambient temperature ponds. Growt...

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...

In an experimental comparison of pumpkinseed Lepomis gibbosus reproduction under ambient and climate change water temperature regimes, spawning occurred earlier in the season, which is likely to lead to greater young‐of‐the‐year survival with concomitant implications in the U.K. under warmer climatic conditions.

This review provides a contemporary account of knowledge on aspects of introductions of non‐native fish species and includes issues associated with introduction pathways, ecological and economic impacts, risk assessments, management options and impact of climate change. It offers guidance to reconcile the increasing demands of certain stakeholders to diversify their activities using non‐native fishes with the long‐term sustain...