Mar 13, 2025 10:05 PM
https://www.eurekalert.org/news-releases/1076835
INTRO: A groundbreaking study, led by the University of Southampton (UK), has revealed that brown trout can successfully navigate beaver dams – obstacles which were previously thought to pose a significant barrier to their movement.
However, researchers say the situation can be complex, with low water flows in some rivers holding fish below the dams, delaying them from accessing spawning areas. They suggest prolonged dry spells, due to climate change, may increase this problem in certain areas of Great Britain in the future.
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."
Beavers were once common throughout Great Britain until they were hunted to extinction around the 16th Century. Their reintroduction in recent years has been heralded as a conservation success story with some 1.2 million of the animals now living wild across Europe. Populations in Great Britain are much smaller, the largest being in Scotland, with isolated populations in the south of England – although DEFRA has just authorised the licenced release of beavers into the wild in England.
The natural engineering of beaver habitats creates biodiversity benefits but has also sparked concerns about potential impacts on local fisheries, such as blocking of rivers and localised flooding. This new research underscores the importance of proactive management strategies to mitigate potential future challenges for fish migration, particularly in a shifting climate... (MORE - details, no ads)
INTRO: A groundbreaking study, led by the University of Southampton (UK), has revealed that brown trout can successfully navigate beaver dams – obstacles which were previously thought to pose a significant barrier to their movement.
However, researchers say the situation can be complex, with low water flows in some rivers holding fish below the dams, delaying them from accessing spawning areas. They suggest prolonged dry spells, due to climate change, may increase this problem in certain areas of Great Britain in the future.
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."
Beavers were once common throughout Great Britain until they were hunted to extinction around the 16th Century. Their reintroduction in recent years has been heralded as a conservation success story with some 1.2 million of the animals now living wild across Europe. Populations in Great Britain are much smaller, the largest being in Scotland, with isolated populations in the south of England – although DEFRA has just authorised the licenced release of beavers into the wild in England.
The natural engineering of beaver habitats creates biodiversity benefits but has also sparked concerns about potential impacts on local fisheries, such as blocking of rivers and localised flooding. This new research underscores the importance of proactive management strategies to mitigate potential future challenges for fish migration, particularly in a shifting climate... (MORE - details, no ads)