Differences in response to liming in a lake-dwelling fish community

Abstract

The Lake Fjorda water system in southern Norway consists of several lakes which exhibit a gradient in acidification. The system is inhabited by populations of brown trout, Arctic char, whitefish, perch, European minnows and Crucian carp. Populations of Arctic char, whitefish and brown trout were nearly wiped out in some of the locations, as a result of acidification, In 1985, Lake Fjorda was limed in order to improve water quality so the fish community would be recovered. Fish stock assessment by means of gill-net fishing in the epibenthic and pelagic zones was carried out before (1983) and three years after liming (1991–1993). Populations of Arctic char and whitefish have not recovered after eight years of liming. Brown trout are almost extinct and do not seem to be recovering. Perch were less affected by acidification, exhibiting good recruitment also before liming.