Fish Swimming Behaviour in Finnish Fishways
Proceedings of the International Symposium on Fishways '95
The Organizing Committee for International Symposium on Fishways '95 in Gifu
While ascending towards a dam salmon (Salmo salar) and brown trout (S. trutta) follow the main flow. According to our observations, it usually takes two weeks until they swim from the turbine flow into the fishway. They often seem to need to get acquainted with the fishway entrance and its flow. While ascending, trout has been measured to spend 1-3 minutes per pool. The ascent tends to speed up further on the fishway. For small coregonids (Coregonus sp.), resting in pools is essential. The velocities of the best resting areas correspond with 1/2-1 BL/s in fishways and in natural rapids. Lamprey (Lampetra fluviatilis) has had difficulties in ascending the vertical slot and Denil fishways.