August 26, 2025

209: Beavers vs Salmon - Balance The Scales with Rob Needham

1 hour 7 minutes

Can beavers save Britain's dying rivers? Are these ecosystem engineers the key to reversing the catastrophic decline of Atlantic salmon, or do their dams create impassable barriers for struggling fish populations? With salmon numbers plummeting by 70% in just 20 years and predictions they could vanish entirely within two decades, the stakes couldn't be higher. The reintroduction of beavers to British waterways has sparked heated debate about their impact on our most threatened migratory species.

In this episode, our guest is Dr Rob Needham, and we talk about his research from Scotland. Rob's long-term study reveals how beaver-modified streams support larger, healthier trout populations, with tagged fish successfully navigating multiple beaver dam crossings. We also talk about research from Norway, and North America that's providing crucial insights for British conservation efforts. For example Rachel Malison’s work in Norway demonstrates that beavers and salmon coexist successfully for past decades on some of the world's most productive salmon rivers. The evidence suggests these species co-evolved together and co-existed for millennia, creating complex ecosystems that benefit both.

From the western United States, Bridge Creek's remarkable restoration story demonstrates nature's incredible capacity for self-repair, with 200% increases in fish abundance following beaver reintroduction. Meanwhile, cutting-edge environmental DNA research is mapping salmon and beaver (and other species) distribution across Scottish catchments, showing how ecosystems can recover. As climate change intensifies pressure on freshwater habitats, the ecosystem engineering by beavers offers hope for building resilient river systems. The message is clear: collaboration between conservationists, researchers, and local communities is essential if we're to harness beavers' restorative power while protecting our precious migratory fish.