GROWTH AND AGE DISTRIBUTION OF A RIVER-DWELLING AND A LAKE-DWELLING POPULATION OF ANADROMOUS ARCTIC CHAR AT THE SAME LATITUDE IN NORWAY

Two populations of anadromous Arctic char Saivelinus alpinus at the sa me latitude (67-degrees-N) in Norway were studied from 1975 to 1989. R iver Beiarelva Arctic char stay for the entire freshwater portion of t heir lives in the main river in running water. The Saltdal Arctic char mainly spawn, and the young stay until smoltification, in a lake that drains to the River Saltdalselva. The river-dwelling Arctic char grow better and smoltify at a lower age and at a smaller size than the lak e-dwelling fish. They also reach maturity at a lower age, but at the s ame size as the lake-dwelling Arctic char. In both rivers, Atlantic sa lmon Salmo salar and anadromous brown trout Salmo trutta are the predo minant fish species. The study demonstrated that anadromous Arctic cha r may exist sympatrically with Atlantic salmon and brown trout in runn ing water. In the watershed where a lake is available, most of the Arc tic char stay in the lake in spite of the better growth and lower smol ting age that they might attain in running water.