Colonisation of freshwater habitats by the European eel Anguilla anguilla

摘要: SUMMARY 1. The spatial distribution of European eels in 18 U.K. rivers was related to distance from tidal limit using a negative exponential model. This function accounted for between 19 and 90% the variation eel density where quantitative data available. For semiquantitative significant predictor densities only six out 10 cases, although all showed consistent decline abundance with upstream limit. 2. The different age groups River Severn an initial rapid dispersion into freshwater followed by much slower rate. Movement population wave-form migration process does not occur this system. Instead colonisation freshwaters can be seen as two-phase dispersion. Phase-1 is driven at point source. Phase-2 commences once become yellow equivalent random diffusion particles. 3. These processes have important implications penetration reduced numbers larvae arriving on coast Europe North America. Eel will decrease more direction whilst it may remain stable or lesser extent estuaries. They are also able explain demography migrating over weirs observations varying sex ratios within catchments. We conclude that model dependent age, temperature, difficulty migration, habitat quality should part management.