Research shows brown trout can pass beaver dams

A study monitoring brown trout movements in two streams in northern Scotland has shown that they can successfully navigate beaver dams in defiance of many people’s expectations.

The research monitored trout movements in two streams in northern Scotland, Allt Coire an t-Seilich and Allt a’Choilich – with the former modified by a series of four beaver dams and the latter unaltered.

The fish were tracked by scientists from the University of Southampton during spawning periods using telemetry technology.

The research found that the fish had high success navigating the dams during periods of high river flows. However, during low flow periods beaver dams posed a greater obstacle delaying or preventing trout movement upstream.

Dylan Roberts, head of fisheries at the Game and Wildlife Conservation Trust who collaborated on the project, said: “Beavers are now back in England and Scotland, but the landscape is very different to when they were last here 500 years ago.

“Populations of many migratory fish, which need free passage up and downstream to access spawning areas and the sea, are now at crisis point and classified as endangered.

“Such studies are crucial to better understand the interactions between beavers and migratory fish like brown trout and salmon.”