From the team at BBC Wildlife Magazine

Beaver dams are good for fish

Anglers’ fears that the reintroduction of beavers to the UK will harm trout and salmon populations may be unfounded, scientists say.

Published: November 19, 2015 at 12:01 pm
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Ponds created by beaver dams are excellent habitat for trout, according to the preliminary findings of a research project being carried out in the north of Scotland.


The discovery is a boost for the many conservationists who believe beavers that are living wild in Knapdale and Tayside in Scotland should be allowed to remain, and that this once-native rodent should be reintroduced more widely throughout Britain.

European beavers from Norway were released into several lochs in Knapdale, on Scotland's west coast, in 2009 and have been closely monitored for their impact on the environment during that time.

In this latest study, to assess the beaver's impact on migratory fish researchers tagged and tracked several hundred trout in a stream that had been dammed to get a picture of both their distribution and movements.

Principal investigator Prof Paul Kemp, from the University of Southampton, said: “It is clear that beaver ponds create excellent habitat for large trout, with trout being more than twice as abundant in the beaver-dammed stream compared with the control.”

There were some negative impacts, Kemp said, because dams can block the movements of trout when water levels are low. “They do appear to move past them when levels rise after rain,” he added.

Trout and salmon must migrate upstream in order lay their eggs, and opponents of bringing back beavers back have argued that the species would negatively affect these economically important game fish.

In 2008, fishery management boards and celebrity anglers called for the Knapdale project to be scrapped (even before it had begun) because of the impact it would have on the salmon industry.

Former England cricketer Sir Ian Botham said: “The Scottish Government should have a long hard think about this. The loss of the salmon industry would be catastrophic for Scotland.”

The Scottish Government is due to make a decision about whether to allow the beavers in Knapdale and Tayside (which escaped from private collections more than 10 years and have since grown to a population of some 200 animals) to remain, and whether they can be reintroduced more widely in Scotland, soon.

Find out more about the Scottish Beaver Trial


For more on the Tay beavers


James FairWildlife journalist

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