Movement and abundance of barbel, Barbus barbus, in a mesotrophic chalk stream in England

We studied movement and abundance of Barbus barbus over three years in two stretches (Woolmer's Park, Holwell Bridge) of a section of the River Lee (Hertfordshire, England) delimitated by water retention structures. Of 349 tagged individuals, 51.8% and 13.3% respectively were recaptured at least once. At Woolmer's Park, 77.1% of the barbel showed limited between-capture movements. There was no preferential directional movement across size classes. Population size first increased moderately (1995-96) and then sharply (1996-97) at Woolmer's Park, and even further later at Holwell Bridge (1998-99). This may reflect a recovery phase in the local population, or possibly a rising part of a cyclic recruitment pattern. Habitat enhancement is recommended over stocking, given the adequate abundance of barbel in areas with suitable habitat.