Re-introduction of Atlantic salmon, Salmo salar L., to the Tadnoll Brook, Dorset.

Abstract

Atlantic salmon were extinct in Tadnoll Brook, Dorset, a tributary of the River Frome. Fry were reared from River Frome native stock and introduced to Tadnoll Brook. Dispersal downstream of the introduction site was high initially, through at least 1km; despite dispersal a density of salmon parr of 8 per 100m² was achieved in the introduction reach. Survival was 71% egg - fry in egg boxes, 4.1% fry - smolt and 2.9% egg - smolt. There were two smolt migratory periods, in the autumn following the introduction, and in the following spring. Approximately 45% of the surviving population remained in Tadnoll Brook for a second summer. Observed patterns were consistent with suggestions that fry and parr distribution is constrained by habitat limitation.