Density effect on growth rate of juvenile Atlantic salmon (Salmo salar) in manipulated large rivers

Abstract

Growth rate of young-of-the-year (YOY) Atlantic salmon (Salmo salar) in low-density rivers was substantial better relative to YOY captured in normal density rivers. Mean growth index ± SD for YOY in low-density rivers was 1.10 ± 0.36 while the corresponding value in normal density rivers was 0.60 ± 0.22. The YOY originated from eight different rivers located in the middle and Northern Norway. Rivers were classified into two types, low-density rivers and normal density rivers. Rivers under restoring after rotenone treatment were used as low-density rivers. Regular rivers, which have not been treated with rotenone, were used to represent normal density rivers. Growth rate (temperature adjusted) comparisons were done by comparing predicted mean body mass of YOY with observed mean body mass of YOY in each river.