Redds of brown trout in the deep channels of a hydroelectric power station

Keski-Suomen taimenseuranta vuonna 2015

Redd Counting for Monitoring Salmonids in Finnish Inland Waters

During recent years, systematic redd counting has been used as a monitoring method of wild Brown Trout Salmo trutta spawning stocks, both resident and lake-migrating, in the Lake District in Southern Finland. Counting is done by wading and viewing with an aqua-scope, and is related to channel microhabitat measurements, to estimation of gravel origin, to regression between redd length and female length, to regression between female length and egg number in redd, and to parr density. This produces valuable information about spawning environment, spawning stocks, and stock-recruitment ratio for management of stream-spawning fishes and river channels. Number of trout redds and of female spawner…