I sure hope you’re sitting down, because this is going to come as a huge shock. It turns out that beaver dams in England affect brown trout pretty much the same way as they affect trout in America! Who could possibly have seen that coming? Not me that’s for sure. Next you’ll be telling me that gravity works the same way in China that it does in Wyoming and we know that’s not true because they are upside down!

Brown trout proven to successfully navigate beaver dams

Findings are published in the journal PLOS One.

The research monitored trout movements in two streams in Scotland — one modified by a series of four beaver dams and the other unaltered.

The scientists observed the trout as they navigated the barriers during critical spawning periods (October to December). The fish were tracked using telemetry technology, where trout are tagged with microchips that are read by antennae spanning the dam structures.

The researchers found that high river flows, triggered by rainfall, significantly increased the likelihood of successful upstream passage. Additionally, larger fish had greater success at navigating the dams. Conversely, during low flow periods, beaver dams posed a more significant obstacle, delaying or sometimes preventing trout movement upstream.

Dr Robert Needham, Restoration Manager at Beaver Trust and former University of Southampton researcher, said: “Our findings highlight how adaptable brown trout are under favourable conditions, regularly passing beaver dams and with certain individuals making multiple repeat passes. However, as climate change continues to bring warmer and drier weather, the risk of migratory barriers may become a concern on certain rivers.”

I don’t know about you but I am GOBSMACKED that the trout across the pond can make it over those nasty monster beaver dams just like they can in America. Who would have guessed?

I guess it has something to do with water flow though. Fish need water. I’m totally shocked about that.

“Our findings indicate how fish response to river modification through the construction of dams by beaver can be nuanced,” says Professor Paul Kemp, the project lead at the University of Southampton. “In general, and if rivers are allowed to respond naturally, the benefits of beaver activity can be substantial from an ecological perspective. However, under some circumstances beaver dams can pose barriers to fish movement, particularly under low flows.

“More research is now needed to understand how beaver dams might impede fish movements in more modified lowland rivers, such as in the south of England.”

True. Our research shows that water mostly runs downhill. But there’s evidence that if there’s a little bump it can stop flowing for a while. More research is needed.

Please give me a grant.