Case Studies of Connectivity and Non-Native Fish Dispersal in the U.K.

As an island country, the United Kingdom was amongst the most active nations during the ‘acclimatisation societies’ era, when humans introduced numerous fish species to the British Isles. More recent fish introductions have been accidental, but in both cases the secondary dispersal of established populations has resulted from both human-assisted introductions (deliberate and accidental transfers) and river connectivity (floodplain connections, inter-basin water transfers). In this paper, we review the role of river connectivity in the secondary dispersal of introduced non-native species (e.g. topmouth gudgeon Pseudorasbora parva, sunbleak Leucaspius delineatus, pikeperch Sander lucioperca, pumpkinseed Lepomis gibbosus) as well as native species ‘translocated’ outside their native U.K. ranges (e.g. spined loach Cobitis taenia, barbel Barbus barbus). In the case of pumpkinseed, we examine the projected dispersal of the species under the predicted conditions of climate change  (increased water temperature [2–5°C] and hydrological variability).