Risk assessments are crucial for identifying and mitigating impacts from biological invasions. The Fish Invasiveness Scoring Kit (FISK) is a risk identification (screening) tool for freshwater fishes consisting of two subject areas: biogeography/history and biology/ecology. According to the outcomes, species can be classified under particular risk categories. The aim of this study was to apply FISK to the Iberian Peninsula, a Mediterranean climate region highly important for freshwater fish conservation due to a high level of endemism. In total, 89 fish species were assessed by three independent assessors. Results from receiver operating characteristic analysis showed that FISK can discriminate reliably between noninvasive and invasive fishes for Iberia, with a threshold of 20.25, similar to those obtained in several regions around the world. Based on mean scores, no species was categorized as "low risk," 50 species as "medium risk," 17 as "moderately high risk," 11 as "high risk," and 11 as "very high risk." The highest scoring species was goldfish Carassius auratus. Mean certainty in response was above the category "mostly certain," ranging from tinfoil barb Barbonymus schwanenfeldii with the lowest certainty to eastern mosquitofish Gambusia holbrooki with the highest level. Pair-wise comparison showed significant differences between one assessor and the other two on mean certainty, with these two assessors showing a high coincidence rate for the species categorization. Overall, the results suggest that FISK is a useful and viable tool for assessing risks posed by non-native fish in the Iberian Peninsula and contributes to a "watch list" in this region.

ABSTRACT1. Diet is an essential element for understanding how the Eurasian otter (Lutra lutra) is re-colonizing its former range in England following a population decline observed in the 1950s to 1970s.2. Otter spraints from the River Glaven catchment (north Norfolk, eastern England) were collected seasonally between 2009 and 2010 from three habitat types (ponds, 'retenus' (small in-stream reservoirs), and stream stretches). Feeding tactics of the otter were compared between habitat types and, using previously published data, with regard to seasonal changes since the 1970s when the species was in decline.3. Otter diet composition varied greatly, with predation on aquatic invertebrates, crayfish, fish, and tetrapods. Fruit seeds were also found in the spraints. Diet generally reflected habitat, with northern pike (Esox lucius) remains found in spraints from ponds and retenus, whereas European eel (Anguilla anguilla) and gudgeon (Gobio gobio) were prominent in spraints from stream sections. Trophic diversity was particularly high in spraints collected next to ponds. Between the 1970s and the present, crayfish, brown trout (Salmo trutta), cyprinids, Eurasian perch (Perca fluviatilis), birds and mammals increased in prominence, whereas eel and threespine stickleback (Gasterosteus aculeatus) decreased, with notable seasonal variations between the study periods.4. Otter spraints revealed few prey preferences, with only that for gudgeon being ecologically relevant. The consumption of popular sport fishes, in particular common carp (Cyprinus carpio), has given rise to conflicts between recreational anglers and otter conservationists, but no demonstrated preference for carp was observed in the present study.5. Overall, otters have increased their consumption of 'less preferred' (i.e. lower energetic value) food types, and because the species normally preys on the most abundant species available, this suggests declines in 'preferred' prey types. These dietary shifts could contribute to otter dispersal and re-colonization of parts of its original European range where food availability may be higher.

–  Feeding tactics, body condition and size structure of two populations of pumpkinseed Lepomis gibbosus from Cabañeros National Park (Guadiana River basin, central Spain) were compared to provide insight into the ecological requirements favouring levels of success/failure in relation to human intervention. Habitat, benthic macroinvertebrates and pumpkinseed were quantified in Bullaque (regulated flow, affected by agricultural activities) and Estena (natural conditions) rivers, from May to September of 2005 and 2006. Significant differences were found in the limnological characteristics between the two rivers. Spatial and temporal variations in diet composition were likely related to opportunistic feeding and high foraging plasticity. Diet diversity was higher in Bullaque River. Electivity of benthic prey showed variation between sized individuals and populations. The body condition of pumpkinseed was better in Bullaque River. Current results show that this invasive species is favoured by human intervention in Bullaque River.

No abstract

1. In response to reported declines in crucian carp Carassius carassius across Europe, studies of the status and population biology of the species in England led to Biodiversity Action Plan priority designation in the eastern county of Norfolk.2. In light of new data on crucian carp populations in eastern England (counties of Essex, Hertfordshire and Norfolk), a comprehensive review of available information throughout its native and introduced European range was undertaken to assess the growth and reproduction at a broader scale, thus contributing to conservation and management strategies at a country scale in the UK.3. For all populations, mean sex ratio was 1:1, back-calculated total length (TL) ranged from 19 to 334 mm, and maximum age was 13 years. Growth and body condition varied greatly across Europe. Growth trajectories in England, Russia and Poland were significantly faster than in Finland. Within England, growth index was lower in Hertfordshire than in Essex and Norfolk, and Fulton condition (plumpness) index was higher in Essex than in Norfolk. 4. Reproductive traits varied greatly both in males and females, with age at maturity ranging from 1.5 to 5 years, and with the shortest life spans observed in England. Length at maturity was usually at a lower TL in males than females (except in Essex populations). Female age at maturity decreased significantly with juvenile growth, which was defined as TL at age 2, the age above which females in most populations achieved maturity.5. Predicted temperature rise (i.e. under a climate change scenario) may benefit crucian carp growth, as predicted for related competitive invaders (e.g. goldfish Carassius auratus). From a conservation perspective, suggested management strategies include reducing populations of non-native fishes, implementing measures of habitat restoration and re-stocking rehabilitated ponds from 'source areas', i.e. those containing crucian carp populations in good status.

The freshwater Fish Invasiveness Screening Kit (FISK) has been applied in 35 risk assessment areas in 45 countries across the six inhabited continents (11 applications using FISK v1; 25 using FISK v2). The present study aimed: to assess the breadth of FISK applications and the confidence (certainty) levels associated with the decision-support tool's 49 questions and its ability to distinguish between taxa of low-to-medium and high risk of becoming invasive, and thus provide climate-specific, generalised, calibrated thresholds for risk level categorisation; and to identify the most potentially invasive freshwater fish species on a global level. The 1973 risk assessments were carried out by 70 ? experts on 372 taxa (47 of

No abstract

Biological invasions are a major threat to global freshwater biodiversity. Competition is a frequent negative interaction between non‐native and native species, and this process is commonly quantified using indirect methods (e.g. dietary overlap, comparison of habitat use/selection). However, direct observation can provide crucial information on these biotic interactions. This paper reviews studies that used direct observational methods to quantify interactions between non‐native and native freshwater fishes. Although laboratory and field studies using direct observations are not common, both have been used to demonstrate impacts by non‐native species on native species. These effects include: (1) altered habitat selection and foraging behaviour and (2) disruption of reproductive behaviour. Direct observational techniques have great potential for quantifying the impacts of non‐natives on native freshwater fishes and can detect negative behavioural impacts that would be missed using indirect methods.