No abstract

Taking into account the continuous increase in freshwater introductions, and to support the recent European legislation on invasive alien species, the identification of priority pathways and gateways of introductions is of utmost importance to develop adequate control strategies. The aim of this paper was to analyse the main pathways and gateways of introductions of freshwater alien species in Europe. Based on a thorough review of the scientific and grey literature, information on pathways, country and year of initial introduction of all freshwater alien species in Europe, was retrieved. The spatial and temporal patterns and trends of biological invasions in freshwater ecosystems in Europe, in relation to different pathways, were assessed. Our results pinpoint the major importance of aquaculture, pet/aquarium trade and stocking activities as pathways of introduction of freshwater alien species in Europe. For species native to some European countries, shipping and inland canals were the most important pathways, highly responsible for the entry of many harmful species. Germany, the United Kingdom and Italy were the main entry gateways of freshwater alien species in Europe. We found a geographical pattern related to some pathways of introduction in Europe: introductions through inland canals were concentrated in Central/North-eastern Europe, while introductions through pet/terrarium/aquarium trade were mainly observed in Central/Western Europe. While Chordata species entered Europe mainly through the three major above mentioned pathways, many harmful Arthropoda and Mollusca entered through shipping and inland canals. The information gathered in this study clearly indicates the entry routes that should be prioritised by Member States, for which stronger control and management actions should be implemented and prevention efforts concentrated under the scope of the related new EU Regulation.

The decline in the European eel has led the European Union to require that its Member States establish an Eel Management Plan, which includes a set of measures to help preserve and restore the wild eel populations. Stocking has been conducted in France since 2011 as part of this Management Plan. This stocking programme is based on a protocol designed by the French National Museum of Natural History and includes an assessment of the short-term (15 d after release) mortality and three recapture surveys at 6, 12, and 36 months after release. The present study aims to assess the different processes influencing the short-term mortality to provide recommendations to reduce mortality and increase the efficiency of the releases. A linear model was built to examine the different variables selected modelling. The resulting model explained 56.4% of the total deviance; the main factor in terms of explained deviance was the operation (31.2%), which actually includes a number of handling parameters. The other factors influencing the short-term mortality were the release year, the fishmonger that provided the glass eels, the duration of stalling (period of captivity) before release, the body condition, the marking, and the type of mortality test. It appears that some of these variables could be adjusted to reduce the short-term mortality. For instance, selecting the most suitable release sites to stock or selecting glass eels with good body condition, adjusting the duration of stalling, or limiting the marking should help reduce short-term mortality.

All native fishes living in the Caribbean island rivers are considered diadromous but few species have been validated as diadromous. In Guadeloupe (Lesser Antilles) as well as in the other tropical islands, the riverine habitats are subject to strong anthropogenic pressure due to resource modifications or dams. The management of fish biodiversity requires knowledge concerning their life history traits and behaviour that are still unknown for most species at a local scale and at the whole distribution area of the species. In a Guadeloupe river, we inferred the migratory patterns of four freshwater fishes common to Caribbean rivers by the analysis of otolith microchemistry. We found two species Eleotris perniger (Eleotridae) and Sicydium plumieri (Gobiidae) to be completely amphidromous with a marine larval phase and a freshwater adult phase. Agonostomus monticola (Mugilidae) was also found to be amphidromous in this system. The fourth species Gobiesox cephalus (Gobiesocidae) showed elemental ratios suggesting an estuarine larval phase and was defined as “limited amphidromous”. The identification of such life history traits, with limited dispersion abilities, argues for specific management measures in tropical island rivers at a basin scale for the conservation of biodiversity.

Gobius salamansa sp. nov., a new species of tropical eastern Atlantic goby (Teleostei: Gobiidae: Gobiinae) is described from the island of São Vicente in the Republic of Cabo Verde. With adults measuring less than 35 mm TL (total length) it is the smallest species among Gobius. It is easily distinguishable from its AtlanticoMediterranean congeners thanks to a unique character: an additional posterior ocular head pore, newly named a', part of the anterior oculoscapular canal and connected to pore a by a suborbital branch. The new species also possesses a rare character among gobiids: a continuous oculoscapular canal, undivided into anterior and posterior parts. The species is distinguishable from its relatives thanks to its distinctive multi-colored (white, red, black, yellow and brown) eyespot, located on the first dorsal fin; by a low number of soft rays on the second dorsal fin (11) and anal fin (9); by row r not divided into two sections; by a divided row d. The two type of specimens were collected at 0.2-0.6 m depth, at the entrance of cracks in compact volcanic boulders forming a rocky islet submerged at high tide. DNA barcoding based on COI of the species compared with sympatric gobiids and species of AtlanticoMediterranean Gobius reveals a high nucleotide sequence divergence [Kimura's (1980) two parameter distances of 16.5 %)], with Gobius ateriformis identified as its closest species. A dichotomous key for Gobius-Mauligobius from tropical eastern Atlantic is provided. It is the eleventh gobiid species, and the fourth endemic species, to be described in Cape Verde.