EN STUDIE AV SMOLTVANDRING MED RADIOTELEMETRI OCH STRÖMNINGSMODELLERING

Other conference contribution, 2004

A study on the effect of the flow field on downstream migration of smolts in a major northern Swedish river (Umeälv) is presented. The study comprises telemetric studies of downstream migrating smolts and three-dimensional computational fluid dynamics (CFD) studies of the flow. The CFD studies are validated with velocity data from field measurements with an Acoustic Doppler Profiler (ADP). The objective of this study is to determine the migration paths of salmon and trout smolts and relate these paths to the flow field. The results from the study can be used to improve smolt survival by taking appropriate measures to divert smolts from the turbines, e.g. by changing spill rules or installing bypass systems. Results from this telemetry show that the smolts move along the main stream of the river. Since this data only yield information on the smolt positions on a 2-dimensional plane it cannot directly be concluded whether the smolt migration is passive or active. Acomparison of the downstream migration speed of fish with the water velocities in the upper water column indicates that the downstream migration is passive.