Growth and Sex Distribution in an Anadromous Population of Arctic Char in Northern Norway

Abstract

Abstract Presmolt Arctic char Salvelinus alpinus in the River Halselva watershed, northern Norway, were analysed with respect to growth and sex distribution. Two main hypotheses were tested: (1) females dominate among the first-time sea migrants; and (2) age at smoltification depends on presmolt growth rate. Our results showed no significant difference in sex distribution of first-time migrants. There was a low frequency of early maturing males in the population, and no differences between the sexes with respect to early sexual maturation were observed. The first-time sea migrants showed a higher presmolt growth rate than the nonmigrating parr in Lake Storvatn, the only lake of the Halselva watershed. Based on both the low frequency of mature pan and the sex ratio in the smolt run, the population of Arctic char in the profundal zone in Lake Storvatn is predominantly anadromous fish. These fish migrate to sea at a greater age than the first-time migrants observed in the River Halselva and are thus “tempora...