home range and behaviour of yellow‐stage European eel Anguilla anguilla in an estuarine environment

The behaviour patterns of yellow‐stage European eels Anguilla anguilla within the tidal waters of the rivers Frome and Piddle, and the neighbouring Poole Harbour estuary (Dorset, England) were examined from July to December using acoustic transmitters and a fixed hydrophone array. Point‐to‐point measures of range varied between 630 m and 4150 m, with no relationship between eel size and range. Eight eels displayed repeated circuits, travelling distances of 440 m to 5060 m over a few hours. Activity was generally, but not exclusively, nocturnal, with the start and end times closely associated with sunset and sunrise, respectively. Neither direction of travel nor average ground speed was influenced by tidal flow direction, and seasonal declines in water temperature did not appear to influence behaviours. These results on distance travelled during regular, nocturnal movements provide valuable insights into the spatial and temporal distribution of yellow eels in an estuarine environment, which can aid the design of survey programmes in terms of the range over which to deploy fishing gears and the number of nights they should be fished. These survey programmes are urgently required to estimate eel production from saline environments for national Eel Management Plans, and the subsequent implementation of effective conservation measures. The strong influence of light regime on the behaviour patterns of eels points towards control of artificial illumination (light pollution) being an important eel conservation measure in this environment, at least. Copyright © 2013 Crown copyright.