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Conference paper2004

Downstream migration of Salmo salar and S.Trutta smolts in two regulated northern Swedish rivers

Rivinoja, Peter; Östergren, Johan; Leonardsson, Kjell; Lundqvist, Hans; Kiviloog, J; Bergdahl, L; Brydsten, L

Abstract

Downstream migration of Atlantic salmon and anadromous brown trout smolts was studied at two power-stations in the flow-controlled rivers Umeälven and Piteälven. Smolts may pass downstream towards the waterpower constructions through the turbine intakes, or pass through the spillway over the dams. Hatchery smolts of Atlantic salmon (n=90) and anadromous brown trout (n=56) were radiotagged, released upstream the hydropower-facilities and tracked while migrating downstream. Simultaneously, velocity and depth profiles were measured. Our findings demonstrate that smolts migrate in the main flow of the river with the highest water velocities, with an average migration speed at c. 0.46m/s (c. 2 bodylengths/sec). Comparing sur-face water velocities (1-4m depths) with speed of smolts indicate that the downstream migration is passive. Most water was diverted to the power-station which resulted in that fish entered the turbine intakes. At Piteälven 83% of the smolts passed turbines successfully while remaining smolts might have lost their tags in the power-station or could have been killed. Model predictions estimate that the future upstream migrating population could increase with 75% in a 10 year period if smolt mortalities caused by the power-station were reduced from 25% to zero

Keywords

smolt flow power-station approach passage

Published in

Title: IAHR Congress Proceedings. Fifth International Symposium on Ecohydraulics. Aquatic habitats: Analysis & Restoration
Publisher: IAHR Congress

Conference

Fifth International Symposium on Ecohydraulics. Aquatic habitats: Analysis & Restoration. September 12-17, 2004, Madrid, Spain