Using the electrofishing database of the French National Agency for Water and Aquatic Environment (Onema), the time trends of 48 freshwater fish taxa at 590 sites monitored for at least 8 years from 1990 to 2009 were investigated. The results demonstrated that species richness increased steadily from the beginning of the monitoring period. This is congruent with the finding that the number of species displaying a significant increase in spatial distribution or abundance was greater than those showing a significant decrease. Some species, however, had declined both in occurrence and abundance, e.g. tench Tinca tinca, common bream Abramis brama, brown trout Salmo trutta and European eel Anguilla anguilla. The species showing the most spectacular colonization were non-native, e.g. topmouth gudgeon Pseudorasbora parva, wels catfish Silurus glanis and asp Aspius aspius. The time trends in population density were related to the maximal body size, habitat requirement, occurrence and abundance and the status (i.e. native or exotic) but not to the spawning temperature.

Life-history reactions of a pumpkinseed Lepomis gibbosus population in north-eastern France exposed to heated waters were studied. The study was conducted from 2001 to 2003 in an artificial reservoir, adjacent to a nuclear power plant, in which water temperatures are cool in winter (8Á2-12Á4°C) and rise early in spring (April: 14Á7°C) nearly 5°C and 3°C over the temperature of its tributary, respectively. Fast growth among young-of-the-year, precocious maturity and short life span were observed, in contrast to related studies. The short life span appeared to be the price paid for early maturity in breeding fish, which suffered high mortality rates just after their first reproduction.

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

Key-words:Proterorhinus semilunaris, Neogobius melanostomus, Ponticola kessleri, invasive species, Rhine basin Three of the four species of non-native gobiids currently reported in the Rhine basin were recently recorded in France: the Western tubenose goby in 2007, the bighead goby in 2010 and the round goby in 2011. The bighead goby and the round goby displayed a very high rate of range expansion, suggesting a human-assisted colonisation through inland navigation. An assessment of the invasiveness potential by the FISK (Fish Invasiveness Screening Kit) reveals a medium risk for the Western tubenose goby, while the bighead goby and the round goby are at high risk of becoming invasive in France. This assessment is consistent with our observations since there has been a steady increase in the range of the Western tubenose goby, although in low numbers, while the relative abundance of bighead goby and round goby, recently arrived in the French part of the Rhine River and Moselle River, can be high. Given their fast expansion, it can be assumed that these species will soon reach other French basins, particularly in the south (Rhône basin) and in the west (Seine basin), and the implementation of measures to limit their spread should be considered. RÉSUMÉColonisation du bassin du Rhin par les gobiidés non natifs : actualisation de la situation en France Mots-clés : Proterorhinus semilunaris, Neogobius melanostomus, Ponticola kessleri, espèces invasives, bassin du RhinTrois des quatre espèces de gobiidés non natifs actuellement signalées dans le bassin du Rhin ont atteint sa partie française : le gobie demi-lune en 2007, le gobie de Kessler en 2010 et le gobie à tache noire en 2011. Le gobie de Kessler et le gobie à tache noire ont fait preuve d'une vitesse de colonisation très rapide suggérant une migration facilitée par la navigation. L'évaluation du potentiel invasif par la méthode FISK (Fish Invasiveness Screening Kit) révèle un risque moyen pour le gobie demi-lune tandis que le gobie de Kessler et le gobie à tache noire présentent un risque élevé de devenir envahissants en France. Cette évaluation est conforme à nos observations d'une progression constante de l'aire de répartition du gobie demi-lune, bien qu'en faible effectif, tandis que les abondances relatives du gobie de Kessler et du gobie à tache noire, arrivés récemment dans la partie française du Rhin et de la Moselle, peuvent être importantes. Compte tenu de leur rapide progression, on peut supposer que ces espèces coloniseront à court terme d'autres bassins français, en particulier en direction du sud (bassin du Rhône) et de l'ouest (bassin de la Seine) et la mise en place de mesures destinées à en limiter la propagation devrait donc être envisagée.

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