Eurasian beaver (Castor fiber) are being reintroduced in many rivers across the UK. There are well established wild populations in Scotland and on the River Otter in Devon, with smaller numbers on the River Tamar in Devon and the River Wye in Wales (as of 2020). There are also enclosed populations of beavers – see map.
Beavers were native to the UK but became extinct in the 16th Century due to hunting for their fur, meat and ‘castoreum’, a substance that beavers secrete from beneath their tails to mark their territories and is used in the perfume industry. This is reflected in the scientific name for the European beaver, Castor fiber.
European beavers and American beavers are different species, but they are very similar in appearance and habits.
Beavers are being reintroduced because they are a keystone species i.e. they have a disproportionately large effect on the ecosystems they inhabit. They are often called ‘ecosystems engineers’ because of the way that they change habitat – they fell trees, dam rivers, tunnel into banks on such a scale as to change the nature of the habitat and the way that water flows, for example their dams create wetlands and can prompt rivers to create new channels.
As with all (re)introductions of species, the case of the beaver is generating much heat in the UK media from many angles: conservation, fisheries, climate change, natural flood management to name but a few.
Beavers and Trout
The majority of questions we at WTT get asked regarding beavers involve passage issues for wild trout around dams. While any ecological interaction between two species is inherently complex and influenced by locality and flow régime for example (in this particular case), we should remember that beaver and trout have co-evolved for millennia and coexist in many locations throughout Europe. However, the landscape throughout much of the UK where they might formerly have coexisted, prior to the extirpation of beaver, has changed considerably and is now subject to a suite of environmental pressures from humans that could influence the outcomes of any current interaction.
Professor Jonathan Grey of the WTT and Lancaster University has reviewed the scientific literature and numerous reports from other organisations. Click on the links below to read the summary paper or full paper:
Note – neither report considers management options in any detail.
River Otter Beaver Trial, Devon
A population of beavers of unknown origin has been present on the River Otter in Devon since around 2008. They were known to be breeding in 2014. DEFRA originally planned to remove them but following a successful campaign it was agreed that the beavers would be the subject of a five-year trial to monitor their effects on the landscape.
Former WTT Conservation Officer for the South West region, Mike Blackmore, sat on the Fisheries Forum for the Devon Wildlife Trust River Otter Beaver Trial. The role of that forum was to ensure that fish and fisheries stakeholders (e.g. angling clubs) were engaged throughout the study and have the opportunity to ask questions and raise any concerns. Mike wrote a very interesting article on the River Otter Beaver Trial for our annual journal, Salmo Trutta in 2019. A PDF of the article is available here.
Beavers in Scotland
Beavers were released into Knapdale Forest in Argyle in 2009 and monitored as a 5 year trial . A wild population also established on Tayside.
Based on the experience of those two locations and other studies, this report on beavers was given to the Scottish Government in 2015.
The Beaver Salmonid Working Group report which provided input to the report to the Scottish Government is available here.
Beavers on Tayside are the subject of controversy as their population has now grown and areas of farmland are starting to be adversely affected. Consequently, some beavers have been captured and relocated, or shot under licence to control their numbers.
‘in some places and situations the activities of beavers can have negative impacts on other interests such as farms, gardens, or other land. Sometimes this can be easily managed to prevent damage such as by fencing vulnerable areas or protecting individual trees and in others there is the potential for more novel techniques.’
Lessons learned from Bavaria
Beavers were reintroduced 50 years ago to a farmed and populated area of Bavaria and their experience has been shared via study tours from the UK.
In 2012, a study group from Scotland visited Bavaria to develop a fuller understanding of how beavers were managed and what lessons could then be implemented in Scotland. The Bavarian situation is regarded by many people as being similar to Scotland, with the system of beaver management being something that we might wish to copy. The reports from the participants are available here.
This video (below) from the Cornwall Wildlife Trust is interesting and describes another study tour to Bavaria. However, there is limited mention of fish and no mention of salmonids.
The Beaver Trust is a charity established in 2019 and their vision is:
‘to recover Britain’s waterways and landscapes through the normalisation of beavers and the rapid and widespread re-establishment of beaver wetlands across whole river catchments.’
The Eurasian Beaver Handbook: Ecology and Management of Castor fiber , published in 2016, contains a comprehensive overview of management issues by one of Europe’s leading experts, Róisín Campbell-Parker.
Images courtesy of the Beaver Trust and (left to right) Josh Harris, Nina Constable Media and David Parkyn