26/2/2021

Environmental engineer or a waterway menace?

Our Head of Fisheries Dylan Roberts looks at the reintroduction of beavers into the British countryside and the consequences for the existing wildlife

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There has been much media coverage about the reintroduction of Eurasian beavers into the countryside, but are they clever engineers whose dams benefit other species or are they a waterway menace? Beavers became extinct in the UK in the 16th century, and almost extinct in the rest of Europe, mainly because of hunting for their fur, meat and ‘castoreum’, a secretion used in perfumes, food and medicine.

Over the last 60 years they have been reintroduced into a number of EU countries, and were reintroduced into Scotland as part of a trial at Knapdale in 2008, where they were granted legal protection status in May 2019. In recent years, beavers have been reintroduced into England under licence from Natural England (NE) mostly in enclosed (fenced) environments. Several ‘wild’ populations have also illegally established, including one in the River Otter in Devon, which was subsequently licensed as an unenclosed, five-year trial to assess the likely impacts (positive and negative) on riverine ecosystem functioning and biodiversity. The GWCT has sat on both the Management and Fisheries sub-groups of the River Otter Trial since 2016.

Beavers are large powerful rodents weighing up to 30kg and live in the deep pools of rivers and lakes. However, if there is no deep water available, they will create deep water by building woody dams, which tend to be on small rivers and streams less than 10 metres wide. They build a main dam where they also construct a ‘lodge’ to live and breed, and then build subsequent dams upstream to ensure that they have long lengths of continuous deep water to access the bank for feeding. Dams are created by cutting down trees, cutting branches and pulling them into the water and made watertight by puddling the upstream side with mud. Dams vary considerably in height from a few inches to over six feet and the subsequent ponds and deep glides can cover large areas.

Their preferred diet is willow, but if it is unavailable, they will cut down and feed on the succulent small branches of most trees and shrubs. As they are rodents, their teeth continually grow, so they will also target the bark of very large hard wood trees such as oak and beech to gnaw. The change in river structure to ponds and deep glides has many benefits for wildlife. They create habitats for pond loving creatures like frogs, newts, waterfowl, wetland plants and fish such as minnows, sticklebacks and lamprey. The ponds can also store sediment and the associated nutrients which are often washed in from ploughed farmland, which can be detrimental to a river’s ecology.

Understanding the challenges

Although there are benefits, beavers also come with a number of challenges and can cause problems to agriculture and forestry where land and crops can be flooded, and trees are felled or damaged. They can burrow into flood defences and the debris from their dams can block flood relief culverts and small bridges. They can also be territorial and aggressive, particularly between May and July when they have young, and attacks on dogs and even people have been recorded. In addition, there can be negative impacts on fish.

Most salmon and sea trout populations in England and Food and Rural Affairs, Defra and Natural England who Wales are under severe pressure and classified as ‘at risk’ by the Environment Agency and Natural Resources Wales. Beaver dams can often prohibit their access into important breeding areas in the tributaries of rivers and also unfavourably modify their nursery habitats. Consequently, in many countries, beavers are actively managed to control numbers and mitigate impacts: in Latvia and Lithuania (respectively 25% and 15% of the area and population density of the UK) beaver populations are 70,000-120,000, and 20,000 to 30,000 are culled (shot) annually under a hunting licence.

The River Otter Beaver Trial

The River Otter Beaver Trial (ROBT) has now reported to Natural England and Defra and we feel that its beaver management process is flawed from a fisheries perspective. The trial was also too narrow in scope to provide robust evidence to inform decisions on further unenclosed reintroductions, and too short to understand the full implications of reintroducing beavers into open catchments. The emphasis was on benefits from beavers to the rural economy and ecotourism, and in providing nature-based solutions to flooding, but not on biodiversity loss arising from construction of dams and other beaver activities.

Given our concerns, particularly on the impacts of their dams on migratory salmonids, we are working with the Angling Trust, Salmon & Trout Conservation, Atlantic Salmon Trust, River Otter Fisheries Association and the South West Rivers Association. We collectively commissioned Professor Ian Cowx (University of Hull International Fisheries Institute) to independently review ‘wild’ beaver impacts on salmon, trout and sea trout with particular reference to UK rivers, including the published science and evidence report from the ROBT. Professor Cowx’s report is now published and has been sent to George Eustice, the Secretary of State for the Environment, Food and Rural Affairs, Defra and Natural England who are due to open a consultation in spring 2021.

Looking to the future - the GWCT position

Based on the report produced by Professor Cowx our position is:

  • Managing beavers and their dams for fish conservation needs to be an integral part of any future beaver management strategy.
  • There is currently insufficient scientific evidence to develop a robust strategy to manage interactions between beavers, their dams and fish.
  • There needs to be fully funded research, including telemetry studies, on the upstream and downstream possibility of a range of dam types, including cascades of dams, and for a full range of species.
  • There should be a cessation of open and enclosed beaver releases until a funded management strategy based on research is produced.
  • Any future management strategy should be simple, low in bureaucracy and similar to other species like deer and foxes.

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Comments

Beavers

at 12:13 on 03/03/2021 by john fisher

As beavers have been around for some 7.5 million years, and salmon for some 10 million years one thinks that they can co exist quite well, it is the impact on humans and by humans that is the problem to all environments.

Beavers

at 11:38 on 03/03/2021 by Chris Weaver

Unfortunately, this is yet another example of "cuddly" conservation, where the reintroduction was undertaken before a comprehensive Environmental Impact Assessment was carried it. It should take a minimum of 10 years for the long-term evaluation to be completed prior to any species being reintroduced outside the control zone. Evan Wright's comment of the effect on freshwater pearl mussels is an excellent example why we must be vigilant in preserving the ecological balance, and possibly illustrates just one of several examples where re-wilding could devastate invertebrates that are key to healthy waterways. Slow and controlled is the only sensible way ahead if Beavers are going to be reintoduced, as long as renegades don't release them everywhere, as we saw with Mink farms.

Beavers v the EA and NE

at 1:27 on 03/03/2021 by Ray Walton

Actually the beavers would do a much better job than the UK Environment Agency and Natural England who 'deliberately' cause more 'in river' and 'riverbank, habitat destruction and carnage by mass healthy tree felling and mass vegetation clearance along riverbanks, mass mechanical ranunculus and other weed cutting and dredging, destroying fish, fish fry, eggs, (including Salmon and salmon parr/sea trout, lamprey, Eels etc.) macro invertebrates (food for fish and lifeforms along the natural riverine food chain)....all in the guise of flood defence. As you know the EA are now beginning to understand why towns and villages flood, where they rush any excess rain and river water off to sea ASAP, by channeling and draining it off the flood plains/natural water meadows where it should be going to slow the flow and store the excess water. They know this all too well but never seem to practice what they preach. The EA and NRA and have always caused the flooding problems and riverine habit destruction in the first place. The evidence is common knowledge and available. The EA Fisheries Dept/NE more recently even promote and create new fish, wildfowl and wildlife habitat by placing felled trees in rivers and to slow the flow...just like the beavers do. The poisons, carcinogens endocrine disruptors (fish sex change/inhibitors) and untreated 'Raw Sewage' being continuously and deliberately discharged into our rivers, streams etc. are far bigger ignored problem in killing fish, non natural breeding and recruitment, fish population declines, wildfowl, bird and wildlife declines which the EA, NE/DEFRA/Angling Trust and Govt... never want to address or make it public knowledge.

Beavers and Salmon

at 23:42 on 02/03/2021 by Nick

Q. What came first the Beaver or the Salmon? A. Beavers Salmon evolved after Beavers in the Rivers already inhabited by Beavers. Q. When do Salmon migrate up rivers to spawn? A. In the Autumn the first big rains that swell the rivers ring the bell for the Salmon to migrate up the River this same swelling of the river causes overflow on Beaver dams making them easy to navigate over the Dams in comparison to a man made weirs. If you want see for yourselves go to Germany go to Norway. you want to waste lots of money on research and undertake studys go ahead or you can take a look at the dozens and dozens of studys already undertaken on Beavers and Salmonids and their effect on the environment across Europe where Beavers have been reintroduced and the findings are always the same no major effects on Salmonids yes manage is needed in some areas due to conflict but it tells you how to do that too. As for comparing Latvia and Lithuania which combined are half the size of the UK you talk about them Culling 20-30 thousand out of a population of between 70- 120 thousand beaver Per year that's a Scource of income beaver skins will always be in demand. So by those numbers the UK could Support a population of up to 240 thousand Beavers so in the future there could be a lucrative Beaver hunting industry in the UK. Beavers slow and clean rivers visit a Beaver site down stream side of a Dam you will find the cleanest water and gravels and you will see Trout spawning there upstream in the pools all the vegetation and the dam itself are perfect nursery habitat protecting small fish from being washed away and predated and Cormorants can't herd them up against a solid wall like a weir to have their fill. Those dams are also a breeding ground for invertebrates the food resource available to the fish because of them is quite incredible which in turn means a water can support more fish and less is needed to be spent on stock fish and their artificial feeds saving Syndicates money and don't all Anglers want more Fish in their Rivers? Beavers not only will save a lot of money on flood defences, stock fish, fish feeds river management in the long run they will end up making you money from the control industry that can be established once they are established

Beevers

at 22:05 on 02/03/2021 by Steve B

Charles Dewhirst’s post about the damaging effect of beavers in Tierra del Fuego is pointless! The Beavers that were released there were imported from North America. They are non native to South America. This is why they have badly damaged the area. The beavers in the UK are native to UK and Europe and quite rightly should be here.

Beavers

at 20:25 on 02/03/2021 by CHRISTOPHER WALWIN

Anyone who has seen Beaver damage first hand will know that they do not stop cutting trees down when a dam is made they just keep on felling trees and building ....this is were "BUSY AS A BEAVER" comes from they never stop .. I am in Canada the HOME of the Beaver its even on our Money !! BUT if you have to work with the Beaver then you have to have a proper culling program in place to go with it .. I tollerate a few Beavers and they are highly ammusing to watch at work ..BUT you cant have too many as that will ruin the ecology of the area ..Here we have a licenced culling and pelts are sold under licence .. and why not they are extremely high quality... On the down side they do not mind what tree they fell including fence posts and they leave dangerous stumps from 1 foot to 2and 1/2 feet above ground . which is a hazzard to stock and people ... They are brilliant to see here in the wilds of Canada but NOT in the UK and EU ,..BE WARNED they are destructive .

Beavers

at 19:16 on 02/03/2021 by Huw Williams

Let’s be clear, we are not Tierra del Fuego. Beavers have evolved here for hundreds of years, we had many more fish and much more wildlife before one main problem, man, not beaver. Should we pause all bangles being born until we know the full impact on the environment, I think it’s pretty obvious that the problem is too much bias, seeing wildlife as property, profit or a product rather than its inherent value in quality of life itself, the only real wealth to be measured. For far too long a small minority of mainly white males who think they are experts, but are actually just acting from a culturally retarded and limited perspective that have lost sight of the legacy of damage and genocide we have inflicted on our wildlife, It is obvious beavers would encourage so much more wildlife, both amphibian and more, we need to dare to dream of a wilder landscape not a more barren desert that serves such a tiny minority. We all want more fish, more biodiversity, more wildlife, so let’s jump out of our small conceptual aches and dare to really research through direct knowledge rather than rely on second hand knowledge. If you do then read “ Bringing back the beaver” by Derek Gow and then give an informed opinion....

Beavers

at 18:12 on 02/03/2021 by David Rook

Beavers in my opinion are as important a trees in water management !

Beavers

at 17:32 on 02/03/2021 by Colin Morgan

If I could endorse the comment of Mr Charles Dewhurst I visited the Terra del Fuego national park in Argentina during 2015 and saw first hand the utter devastation that the beavers had caused! I believe this was a result of a failed experiment to re introduce Beavers to the area which has resulted in the Argentine government taking steps to eradicate them. I would hate to see this problem replicated in Mid Wales.

Beavers

at 15:48 on 02/03/2021 by Peter Minter

I can only echo Charles Dewhurst's point about beavers in Tierra del Fuego. The effect can be seen all the way round the coast as far as the Irogoyen. The end result is not conducive to wildlife. I do agree that most of the problems in our rivers are man-made, but that doesn't mean we should ignore them when considering the impact of introducing beavers.

management of beavers

at 14:27 on 02/03/2021 by Curt Gesch

Dear Friends, I was born and raised in Wisconsin, home of the great ecologist, Aldo Leopold. He "wrote the book" on game management in the U.S. and then later retreated from an emphasis on management by cull. One of his credo statements was "keep all the parts." Trying to maintain a certain cultural ideal of rivers or countryside without the parts that created it is probably more ideological than scientific. Having said that, when beavers are introduced and they overproduce themselves, why would countries like Latvia shoot them. There are good, humane traps that can kill them and preserve the furs without damage from rifles. I know, I know--I come from North America and the fur industry doesn't exactly thrive in the UK or EU, but wise use of valuable creatures ought, I think, to be part of any attempts at management.

Beavers

at 14:19 on 02/03/2021 by Andrew Bowell

I would love to see Beavers in the Welland catchment area. Plastic is a bigger problem, blocking drainage channels, culverts and bridges. And if dogs have been attacked by beavers with young, then I would suggest the dog owners avoid areas where Beavers live, or at least they are kept on a lead. The benefit of having Beavers in our rivers far outweighs any detrimental effects. Beaver activity can also stop flooding in certain places. Scotland is famous for Salmon fishing, but the fish coexist happily with Beavers. I say lets have more of these beautiful creatures for people to enjoy. I also support the reintroduction of lynx into the UK.

Beavers

at 12:48 on 02/03/2021 by Charles Dewhurst

Anyone wishing to see the results of releasing beavers into river systems should look to the area of Tierra del Fuego around Ushuaia. Some years ago an attempt was made to farm beavers for fur. This proved unsuccessful due to the fact that, although the climate is far from sultry, the winters were not cold enough to get quality fur and the experiment was terminated. Rather than removing the beavers , they were simply released to the wild. The result has been that wide swathes of riparian land has been colonised and the natural drainage has been seriously disrupted.

Beavers/otters

at 12:44 on 02/03/2021 by Michael Younger

I think otters cause more damage to other wildlife in and around waterways

Beavers & fish

at 12:43 on 02/03/2021 by Sam Gandy

Beavers have co-evolved and cohabited with fish in aquatic environments for millions of years. Beaver eco-engineering markedly increases invertebrate abundance and species diversity - given that all UK fish are omnivores or carnivores, this has important implications for their food availability. Beaver dams also create deeper pools of water - these can be important at times of low flow during the summer, when salmonids are at risk of heat stress (with greater extremes in flow likely in the future in the wake of climate change). Beaver dams also filter out sediment and fertilisers from agricultural runoff, which in turn improves water quality downstream - this is important given that all British rivers failed on their chemical status following a recent assessment. Apparently 70% of the world's Atlantic salmon spawn in Norway, and of their top ten salmon rivers, seven of them have beaver, and six of them are at capacity for beaver. Regarding salmonids, quoting the findings from two different studies: “As a result the abundance of trout is substantially higher in the beaver modified stream, and what is more the trout in the ponds tend to be much larger than in the control stream." "Beaver dams did not block the movement of juvenile salmonids or their ability to use upstream habitats. ... The small scale of habitat alteration and the fact that fish were able to move past dams makes it unlikely that beaver dams negatively impact the juvenile stage of salmon or trout populations." Beaver dams may impede fish movement to some degree at times of low flow, but man made obstructions such as dams and weirs pose a much more substantial barrier to fish movement. https://onlinelibrary.wiley.com/doi/abs/10.1111/eff.12539 There is some nice footage from the Devon Beaver Project of sea trout jumping over beaver dams, and brown trout seem to be coexisting with beavers without issue on the River Otter. It's interesting to note that brown trout do better in beaver eco-engineered waterways in Patagonia, Argentina, where both are alien species. Quoting from a review study, looking at many different studies on beavers and their effects on fish on both sides of the Atlantic: "The majority of 49 North American and European experts considered beaver to have an overall positive impact on fish populations, through their influence on abundance and productivity." https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-2979.2011.00421.x?fbclid=IwAR38VvKJYTrSo_EsfK-taOXxDRApicnt694uciWniPVgPi2JX05vcnJYhkg An informed view on this topic by an angler shared below: http://beavertrust.org/index.php/2020/07/03/beavers-and-angling-from-separation-to-assimilation/?fbclid=IwAR0tzRWS4Dp7SYnfEIQ2gojC_bUo-la3vn3UPbcdP55Zs8PJt2m56Ufiu4o It's worth bearing in mind that fish decline is very much down to human influence as opposed to anything to do with beavers. More research is warranted but I don't agree with GWCT's position here - it would be better to allow their reintroductions to some areas and river systems and study their effect in situ rather than seeking to restrict the reintroduction of a very important member of a fauna that could breathe some much-needed life back into our waterways.

Beavers and feeding pheasants

at 12:18 on 02/03/2021 by Nicholas Watts

We certainly wouldn't want beavers here in the fens. Thank you for the tips on a rat proof feeder, we will try it out and as you say the small birds want feeding as well right through until mid June. Millet and oil seed rape suits most of them as they have never been used to sunflower seeds. It is a pity that more shoots don't take up your advice of feeding after the shooting season ends

Beavers

at 11:20 on 02/03/2021 by Charlie Tuke

In Dorset, a pair of beavers have been released into too small an enclosure, on the fabricated pretext of purifying the water. The Dorset Wildlife Trust ignores the fact I have planted over 5000 trees, have not even tested the water and do not care about any effects on the trout farm downstream. The positioning of this vanity project has not been thought through, and the landowners concerns been totally ignored. It is only a matter of time before someone releases these rodents. DWT’s arrogance has been breathtaking throughout this project.

Beavers

at 10:52 on 02/03/2021 by John Barker

If I went round with an axe and cut into mature trees, causing their loss I would be singled out for environmental vandalism. Rewilding is not thought through in regards of the long term issues,only short-term possible benefits, or too massage someone's ego involved in the scheme.

Beavers

at 9:55 on 27/02/2021 by Evan Wright

In West Cumbria we have two "small" spate rivers with populations of freshwater pearl mussels. These are endangered and highly protected. Their lifecycle depends upon the migration of the Atlantic salmon into and out of these rivers. Anything that could obstruct this, for example a beaver dam would be detrimental. Hence the introduction of beavers into this area could potentially be illegal and certainly irresponsible. Recently, two man made weirs (dams) have been removed, by the EA and the Rivers Trust from one of these rivers, specifically to help ensure the survival of the mussels. There are other rivers in the UK with similar endangered populations of freshwater mussels. This needs to be considered when releasing beavers into the wild, both in terms of release sites and their potential to seek to populate wider areas.

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