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

Atlantic salmon had become extinct in Tadnoll Brook, Dorset, a tributary of the 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 1 km; despite dispersal a density of salmon parr of 8 per 100 m2 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 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.