Movements of the European eel (Anguilla anguilla) in a chalk stream

The movements of wild European eels (Anguilla anguilla L.) were monitored continuously over a 2-year period in a tributary of the River Itchen, Hampshire, UK, using a passive integrated transponder (PIT) antenna system. The time of these movements was then related to a number of monitored and calculated environmental parameters. No eel movements were recorded in the winter months when mean stream temperature was below 10 degrees C. The numbers of movements peaked in May, when mean water temperatures and day length were increasing. The movement of eels was significantly (P < 0.001, R-2 = 0.45, N = 72) correlated with the time of sunset, with the majority (72%) recorded during the hours of darkness. The results of this investigation have implications for the design/timing of surveys of yellow eel populations and their habitat associations and suggest that successfully determining the microhabitat preferences of active resident eels will require remote monitoring throughout the 24-h period.