Sammendrag
Fjorda in Oppland is an area with a network of small lakes, located on the hill west of Randsfjorden. It is one of several acid-sensitive areas in the inner parts of eastern Norway. During the 1960s the brown trout disappeared from small creeks around Fjorda. Especially the char populations seemed to suffer from acidification. In 1990, test fishing was conducted in several lakes in Fjorda before liming. In addition, test fishing results are reported from small lakes investigated in 1986 and 1989. The lakes are dominated by perch, with varying, but often small populations of char, trout and whitefish. Perch was smallish in all lakes, with growth often stagnating between 15 and 20 cm. Age analysis for perch showed varying age structures, with one to three dominant age groups, up to 6 years apart. Lack of age groups is not believed to be directly related to acidification. Apart from the Lake Bjørnsjøen in September 1989 (N = 18), catches of brown trout were small. The fishes were mainly within in the age groups 2 + -7 +, with stagnating growth around 30 cm. Most whitefish were caught in the Lake Hauken in August and November 1990 (N = 6 + 5). Whitefish were represented with age groups younger than 27 + (N = 7) and older than 34 + (N = 4). The oldest whitefish belonged to the age group 38 +, and was, in other words, born in 1952! Most chars were catched in Lake Hauken in November 1990 (N = 31). The fishes were larger than 21 cm and distributed on the age groups 4 + -11 +. The growth stagnated between 25 and 28 cm. Trout catch from Svarttjern in 1986 (N = 12) included fish under 28 cm, distributed on the age groups 6 + -12 +. Growth stagnated at about 30 cm. Mesh sizes of nets that were used in 1986 is not known