The Urban Waste Water Treatment Directive: Monitoring the Arctic charr population of Windermere, 2006

1. The Arctic charr (Salvelinus alpinus) is widely recognised as a species of extremely high biodiversity conservation value in the U.K., but at the same time it is one of the very few lake fish species to be exploited on a commercial or semi-commercial basis. In Windermere, where populations of spring- and autumn-spawning Arctic charr exist in the north and south basins of the lake, this nationally rare and environmentally intolerant species faces significant local pressures. 2. The primary objectives of the present study were to monitor the Arctic charr populations of Windermere by hydroacoustic surveys during day and night at approximately monthly intervals throughout 2006, thus maintaining a programme initiated in 1989. In addition, secondary objectives were to examine 1990 onwards components of catch and effort data from the lake’s Arctic charr fishery and, in response to recent dramatic changes in the fish community, to examine selected 1990 onwards components of long-term population data collected for Arctic charr, perch (Perca fluviatilis) and pike (Esox lucius) outside the present project.