Beavers.

Beavers are animals.

And all the topics around beavers is something that is like right up our alley.

What we do in this podcast, because when we talk about beavers, we talk about habitat restoration, we talk about nature restoration, we talk about species restoration, popularly referred to as reintroductions.

Listeners to this podcast know what I think about the term reintroductions, but I guess we stuck with it.

So we talk about reintroductions and we also talk about human wildlife conflict.

So there are these three things that are going on for beavers that make them very interesting for me and for you and for this podcast.

Second animal fish that we covered comprehensively on this podcast is salmon.

As you know, salmon and salmonids in general are facing catastrophic declines.

We covered all the aspects of it and biology and what is impacting probably since very early episodes, topics about salmon were here and there.

And what is interesting is that beavers and salmon are sort of on the intersection right now.

And beaver's numbers are going up from extirpated, they are in their thousands right now, probably pushing 2000s and salmon is still catastrophically declining.

And obviously there is this tension that on one side beavers are restoring habitat, are restoring freshwater habitats, which is good on another hand because salmon are in such a catastrophic decline and it's a death by thousand cuts.

Those who care about salmon and salmon says like, oh, this is not what we need now.

Rivers being changed by beavers and their dumbs and so on.

So this topic is something that I want to make a podcast and make an episode for a long time.

But now we have even better reasons to do this episode because there is a film coming up your way titled Balancing the Scales which deals with exactly this subject, the subject of interactions of beaver and Samanids.

And today it's my great pleasure to welcome to the show Dr.

Rob Needham, who is one of the scientists featured in this film.

Rob, welcome to the show.

Hi.

Thank you.

Thank you very much for having me.

It is great to have you.

And we spoke before we started recording that this is something that I want to do the podcast on this topic for quite a while.

And you were.

And your work was on my radar as well, even before the film was.

Was the premiere already or was the is it premiere is going to happen?

No, it has, it has premiered.

Okay, that was at the beginning of the year, back in February.

Okay, the first one.

And you're still screening the film?

Yeah, we're still doing lots of screenings, private screenings at the moment, but it's free of Charge private screenings, just to try and keep track of sort of the number of people that we can reach with the documentary.

But in October, it will be on The Beaver Trust YouTube channel, so anyone can watch it.

Oh, this is what I was referring to.

That a public premiere is still to happen.

Public folks, you know what to look for.

So, Rob, we are going to do what we always do in this podcast, which is we're going to jump right in and tell us is it problematic for Samon and Samonids to have beavers around.

And I understand that this is like, straight away, I'm just like, bomb.

But from there we're just gonna go to the details of your research and all those things.

But like a top contour.

Is this something we should worry about?

I mean, my personal opinion and the work that we conducted would suggest that currently it's not something to be concerned about.

I mean, it is a very complicated situation.

It's very nuanced.

It's going to be very site specific.

It's going to be very species specific.

Obviously, salmon and trout have different habitat requirements, so we need to consider different species of salmonids separately.

But I mean, a lot of my work has been focused around brown trout.

So a lot of that can be sort of.

You can associate that and you can look at that and replicate it with certain aspects of salmon.

But there's going to be other factors that are going to be of a concern when it comes to salmon as well.

So I think, as a general, I would say no, I think.

I think we need, as you've already said, salmon are in a catastrophic decline.

Beavers are going up.

The causes of salmon decline are numerous.

A lot of it is what's happening at sea.

We're getting a sort of a massive reduction in the returning salmon that go out to sea.

We're seeing about 2% of the juvenile salmon that go to sea are coming back into our rivers, which, when you think about it, is a very disturbing, worrying percentage of salmon returning.

So it's down for, from 30% or.

Something like that, 30, 40%, sort of 50, 60 years ago would be returning, and now we're down to sort of 2%.

So, yeah, it's a very disturbing figure.

But I think there's lots of science that has shown that what beavers can do can benefit lots of fish, salmonids, trout and even salmon in certain life stages as well.

So I think if we can sort of work on the freshwater aspect and if those salmon that are going.

Those juveniles that are going out to sea, if they can be in the best possible body condition.

That's only going to increase their chances of survival.

And there's evidence suggests that beavers can help with that.

People who are maybe even, you know, hearing about this for the first time, what are the concerns about presence of beavers or impact that beavers may have on.

On.

On salmon and salmonids?

And then maybe from there, would you mind describing your experiment, your research, how it was designed, conducted, and obviously what were the results?

So I would say the biggest concern is the presence of beaver dams acting as barriers to upstream migration of adult salmon and the downstream migration of juvenile salmon when they head out to sea.

So that would be the biggest sort of concern.

So as part of my PhD, sort of, my aim was to try and answer this, looking at a brown trout population and to see how these trout were actually sort of navigating dams.

So what we did, we conducted a study in the highlands looking at a series of four beaver dams.

And we used telemetry to monitor the movement.

So we put microchips, so pit tags in approximately 1,000 fish, 700 of which were then used as part of the study.

And we looked at how, so we could then see individual.

We could identify individual fish.

So we knew the size of the fish that was approaching.

And we would place an antenna below each beaver dam and an antenna above each beaver dam.

And each of these were sort of in sequence.

So we knew that when fish approached antenna one, that was then below dam one, and if we then recorded them on antenna two, that meant that they'd passed the dam and then antenna three was below dam two, and then so on.

So we then could obviously tell how individual fish responded to these dams.

We could see sort of motivation levels.

We could also see how long fish tried to pass the dam.

So looking at migratory delay, which is obviously a concern because even if the fish do get over, there's evidence to suggest particular anthropogenic dams that holding fish below these dams and delaying their movement upstream increases their risk to predation and a potential reduction in body condition.

So that was really helpful that we could see that.

And I mean, ultimately the findings, what we saw were that there was, at the beginning, there was a lot of exploratory movement of the trout approaching the dam.

And this was sort of early on in the autumn.

So what we saw then was kind of, what you could say, an increased, sort of an increased period of migratory delay.

But once the rains arrived and the water conditions were correct, we saw some quite rapid movement of fish up through the whole system.

In like, in some cases, in a day, they managed to pass all the series of the four dams, whereas other fish didn't even make it past dam one.

So if one fish can and another can't, you've got to sort of ask the question of like, motivation levels as well and the passability.

So we looked at that and ultimately what we saw was during periods of high flow, we were getting a much greater rate of passage than in years of low flow.

So we did the study.

We were lucky to do it over two years.

And even we were even more fortunate that the first year was really wet, lots of rain, and then the second year was really dry and very cold.

So we had two years which were so that we could compare against in terms of environmental conditions.

So in 2015, when we did the, when we started, we saw sort of some of the dams, we were seeing 80% passage efficiency, whereas in 2016 that was massively reduced.

But there was no water coming over these dams and a lot of the beaver ponds were frozen.

So it's, as I say said earlier, it's very nuanced.

It's got to be site specific and there's environmental factors to consider as well.

What was the process to, you know, even decide to, to do this research and was it difficult to find a place and design the study and all these things?

So I think what this stems from.

So back in 2009 was the official Scottish beaver trial, when the first wild trial, reintroduction of beavers to Britain, occurred over on the west coast of Scotland at Knappdale.

And during this process, there was a working group set up called the Beaver San Wanted working group.

And ultimately they identified that further research was required to look at the impact of barriers of beaver dams as barriers, because there was obviously lots of work done in North America, in Europe, Scandinavia, but I think it was seen that, well, we need to see what happens from a British context, what happens in Britain.

Our rivers are different, we're heavily canalized, that sort of thing.

So I think that was sort of instrumental in establishing the work.

It wasn't easiest to find sites because obviously beavers are low in numbers, or they were then, they still are.

Ultimately they're high in certain areas.

So, yeah, so that sort of led onto that.

And we were very fortunate to find a site that had a series of dams.

They were established, there was a population of migrate of brown trout.

They are the resident form.

So they're not connected to the sea.

There's an impassable waterfall downstream of our study site.

So we Weren't able to look at the sort of anadromous impact and the effect of oceangoing movements.

But as a first port of call, it's sort of the first study that's been conducted in Britain looking at how barriers affect fish passage.

And I think one of the important points to sort of look at and sort of recognize here is there was a literature review done by Professor Paul Kemp at Southampton University and others and that was commissioned as part of the Beaver Sun Wanted working group.

And barriers were.

So this looked at all the published literature across the globe on beavers and salmon and other species of fish.

And ultimately one of the interesting sort of statistics to pull out of that, shall we say, was that beaver dams were classed as a barrier to fish passage in 80% of the published literature, but only 20%, just over, I think it was 21% could sort of back this up with any data.

So it was.

So give or take, it was 79% of these statements were speculative.

So I think that sort of drove that.

Okay, well if, if there's such an issue, let's, let's look at this, let's try and answer this.

So that kind of drove that sort of study and sort of pinpointed where we wanted to look at in terms of the PhD research.

And did you approach this from the, from, from the fish side or from the beaver side?

I've been a very keen fisherman since I was 4 years old and I worked on the Scottish beaver trial.

I love all wildlife, I love fishing.

So for me it was kind of okay, I'm going to get paid to do a PhD.

So it was quite on two things that I really enjoy and really interested in.

So I was quite fortunate.

So I mean, some might say, well, that's not a balanced view.

But as far as I'm concerned, it is a balanced view because I met obviously as a fisherman, I want to see healthy stocks of fish in the rivers as well as healthy populations of beavers.

Yeah.

And you know, like this is, this is what I, what I say, this is such interesting thing and that interaction between the two species because usually anglers are, you know, very keen on nature and they want habitats restored and they want wildest or they want clean rivers and, and, and so on.

And so you would think that anglers will be like the natural ally for beaver introductions.

But there's like, oh ho ho, no, because they gonna affect our salmon or you know, this sort of logic.

So that was interesting to see this tension.

Do you have a similar experience?

Yeah, very much so.

And I think that that sort of, that fear, that concern has been sort of exacerbated by the current decline in salmon numbers.

But as it stated, I mean, our rivers, a lot of our rivers are just, they're trashed.

The condition of our rivers are so poor that we need to start somewhere.

We can't fix overnight what goes on out at sea.

We can't fix global warming overnight.

There are things that we can do to help improve rivers.

There's lots of river restoration projects and knowledge out there that use processes which basically beavers do.

The introduction of woody debris into rivers to create a habitat, refuge, shelter.

But equally to deflect flows, to change flow patterns, to create that sort of variability in the water in the river, in the flows to create multiple different habitats.

You get slack water behind this woody debris where the sediment builds up, and then you have the faster water coming round.

This fallen tree, for example.

And in that faster water is where you're going to find your gravels and your pebbles and your cobbles.

So you've got that sort of spatial, sort of temporal change in habitat types.

And when that tree gets washed down in a flood later on in the year or in two years time, that whole process starts again and that tree might end up somewhere else in the river.

And that sort of, that change, that sort of heterogeneity, that sort of, in that river system sort of is constantly evolving.

And I think one of the other points is obviously beaver dams, that they're not permanent structures, they can remain in the environment, but ultimately as beavers die as sort of resources.

So beavers will basically build a dam for two reasons.

Ultimately, the first is to ensure that the entrance to their burrow or lodge is submerged, so it remains underwater.

And the other damage.

So they might build a dam to flood an area so that they can access, feed, forage resources.

So if there's a patch of willow trees that the beavers would have to walk across land, if there's a possibility, if they build a dam in a certain location, they can flood that and they can swim in.

So once they've fed on that area, they're not going to maintain that dam anymore.

So that dam will then just deteriorate and the water behind it so the trees.

And then you've got that again, it's that constantly evolving habitat type.

So where that area's been flooded, it's held sediment, there's standing deadwood, which is obviously brilliant habitat for invertebrates, nesting birds such as woodpeckers.

That standing deadwood then falls eventually.

So you then got fallen deadwood again.

Different habitats are created and it's that process of succession.

So when these dams are neglected or deteriorate and disappear, they eventually sort of, well deteriorate and then flows.

But what you've got left there is you've got a meadow which is high in nutrients from all the sediments that have been collected.

And then you get, it starts again.

So you then get different grasses and plants coming through.

Trees will self seed, so your willow starts coming through and you're older.

So it's that process.

But it's just recognizing that beaver dams are very different to a concrete weird or a hydroelectric dam.

They are natural structures made of natural materials that our rivers need.

But equally some of our rivers, they are so heavily canalized and changed and altered dams in certain locations may cause issues where they're not sort of, they're not ideal.

So it's having that open mind approach, I think to it.

And it's sort of weighing up this sort of cost benefit analysis and sort of where is the best place, where can we maximize the sort of benefits from what these beavers do?

I mean, if you look at some of these natural flood management projects, they cost millions and there's constant maintenance and all of this.

And beavers can do this for free.

So we need to find a way to sort of use this, never mind.

How awful they look.

It's just like a concrete channel.

It does the opposite what it's supposed to do.

Right.

Because it just speeds up the water so it quickly passes the area that might be flooded.

But that's not exactly what you should be doing.

No.

And I mean sort of moving away from fish for a second is you've got to look at the sort of the big picture in terms of what beavers can do for us, for humans.

So ecosystem services.

And there's multiple published literature, particularly from the group of scientists at Exeter, including Dr. Alan Putter, Professor Richard Brazier.

They've done lots of studies that look at this and they've shown that where there's beaver dams, that peak flood event is reduced so that water is held back behind dams and is released slowly rather than coming down the whole river system in one go and causing floods.

And there's been evidence that villages that are subjected to flooding before beavers, with the reintroduction of beaver enclosures upstream, has seen a reduction in flooding of those villages.

So not only can they help flooding in terms of reducing flooding, but then on the flip side, we haven't really had rain for six, seven, eight weeks.

And our reservoirs are drying out, we're losing water.

But where these beaver enclosures are, where there's beaver territories and there's dams, these dams have held that water back because they've stored it over the winter.

It's increasing, it's pushing it laterally out and it's mixing with that groundwater.

So it's helping maintain the water table at a particular height.

So I mean, from what they can do for us is actually quite phenomenal in terms of A, reduce flooding, but B, reduce drought.

Yeah, yeah.

And we, we spoke about beaver's reintroductions.

Actually I was specific episode about with Beaver Trust.

It was very ancient, episode 91.

So some few folks might go back there if you want.

Rob, you mentioned something that is very important, that rivers in the UK are trashed, quote, unquote.

I think that's a, that's a scientific term at this point.

And from what I got from the, from the film, because when I was watching this, this, this private screening, and correct me if I'm wrong, the part of that is like the river needs to connect with the floodplains and when it connects with the flood plains, then it creates this opportunity to fish, to pass the dam.

And my thought was like, okay, but is the river, does the river have that?

Like, does all the rivers or some rivers, a majority or minority of rivers, have this capability to connect to the floodplain?

In other words, is it not the case that some rivers are just, you know, effed beyond recognition?

And that's the case when actually beaver, beaver presence, where on one hand they will be the most important, most needed, at the same time, that's the place where their presence might be detrimental to this migrating fish or the fish who needs to move past them.

Like, curious of your comments.

Did I get that right or is it something.

Yeah, no, basically, yes, absolutely.

That's sort of, that's.

You've hit the nail on the head there.

Yeah.

A river with connectivity to the floodplain is obviously, it's that river can act naturally, natural processes can happen.

So in the beaver's dam that water has to find a way downstream and it will more often than not cut round these dams and create these natural bypass channels.

And a lot of hydro dams are often trying to recreate these natural bypass channels rather than having fish ladders and things like that.

It's the new sort of design, new sort of methodologies to try and create a natural stream that flows around one of these weirs.

So.

Absolutely.

So where you've got that connectivity, the issue of fish passage is going to be reduced.

But rightly, as you say, when these rivers are canalized and they're not connected to the floodplain, you are, that's where you are going to see the issues.

So it's a bit of a flip one.

I mean, we're still building on floodplains.

We're farming land right up to the riverbanks.

There's no sort of buffer zones there.

There's no riparian corridors.

So regardless of beavers and fish, all wildlife needs corridors, particularly along rivers, because they are, they are corridors in themselves in our landscape.

So having those buffer zones moving that land use back is only going to be beneficial.

So.

But I mean, in terms of these rivers that are completely canalized, so look at rivers going through urban landscapes.

There's not a lot we can do about that.

But we have to think in some of these rivers that are completely trashed and canalized, are they great places for fish?

Are they going to be great places for beavers?

So these canalized systems in urban environments, they're not going to be the best places.

We've also got to consider that, generally speaking, as a rule of thumb, because never say never, but generally, beavers won't dam a river that's over 6 meters wide.

If it's over sort of 70 centimeters deep, it's very unlikely to dam it as well because of the amount of water.

So you can automatically, if you think of our river system, you could map very quite quickly the areas that beavers could dam.

If the data is there, you can often overlay sort of areas of concern with fish passage with.

And again, models have been developed by Exeter University which look at beaver dam capacity.

So it looks in a landscape where beavers are likely to dam and where they're not likely to dam, because you've got to consider that they're not just going to build dams for the, for the sake of it.

As I said, there's two main reasons they're going to build dams, because they're not.

There's no point in just building it.

They don't build dams for the sake of it.

But you've obviously got to factor in that in those areas that they can dam, that has to be suitable habitat for them to want to be in that area as well.

So I think, and as we're saying, so I think a good example is beavers have been now sort of living wild, sort of from unauthorized populations in Kent for nearly 20 years.

And we did a big survey a couple of years ago, and I think we found two small dams and they've been there for like 20 years.

So beavers that are living on main rivers, they're not going to dam.

That's interesting thing that, that they might be there, but they're not, not damming anything anyway.

So that's not.

So this is, I guess, this complex picture that emerges here that I just, I'm just delightful to dive into these, these, these nuances.

But yeah, but on that.

So obviously it's a lot of these salmon.

Some of the salmon rivers, they will often spawn right up in the headwater streams where the beavers can dam and ultimately where we want to see the beavers doing the most, because that's where they're going to have the most benefit, is damming in the headwaters and holding that water back in terms of flooding and things like that.

So we just need to sort of factor in that.

But we just completed a big survey of the whole of the Tay catchment and we've recorded all the dams and we're going to look at that.

But what it's kind of showing at the moment is on the River Tay, for example, the beaver and salmon overlap is very, very minimal.

Salmon are spawning in areas that beavers aren't damming in because A, it's not optimal habitat for beavers, or B, they don't need to damage or physically can't dam.

So we're kind of building up a picture here, and this is anecdotal.

This is sort of 20 years again with sort of 20 years down the line nearly with beavers in Tayside, and we're seeing very minimal conflicts.

That's not to say they're not going to happen another catchment, but I think it's important to sort of recognize that the River Tay is a very important salmon river in Scotland that has had.

That's got the highest population of beavers and conflicts are minimal.

So, and I mean, like when I say minimal, people are sort of saying that they're just not overlapping, they're utilizing different areas.

That's interesting because, you know, one on one hand, when we started this, this conversation or this part of the conversation, when we said like, okay, the rivers are in such a bad state that there actually might be a problem and there was like a little bit of a chicken in the egg.

But it seems to me now that that's actually not gonna be a problem because those rivers are, they're, they're bad for beavers and salmon alike anyway.

So they're sort of fall into like a river restoration category first before we can have that problem and I know that now you mentioned that it's very specific to the habitat and you're mapping that.

So did I get that right at that exercise of mapping on potential impacts and potential conflicts between beavers and Samoa.

This is like an ongoing work right now?

Yeah, absolutely is ongoing.

There's other PhD work that's been done.

Current PhD student up at the University of Highland and Islands, James MacArthur.

He's done sort of a new approach which is looking at EDNA so environmental DNA and he's been looking at how, and this is across the Tay catchment.

So my, my study was very site specific but James has done this across the whole of the Tay catchment and he's looking at.

So looking at EDNA and how the presence of beaver EDNA might affect the presence of Atlantic salmon edna.

This work isn't published yet but, but it's under review so it's hopefully be out very soon.

But it's available in pre print online.

So I feel I can sort of say what the sort of the initial findings are and that is that there doesn't seem to be any correlation between beavers and Atlantic salmon DNA.

So suggesting that there's no negative impact on Atlantic salmon DNA on Atlantic salmon.

But it has very interestingly shown there's a positive correlation between European eel, which is a species again 90% decline between European eel and beavers and it also seems to be benefiting Lamprey as well.

So there's, there's lots of work going on and we've got a new PhD starting at the University of Southampton as well.

So the work is ongoing and just hopefully trying to fill in those blanks.

So I think now is the moment for the question about resolving potential conflict.

Right.

And I can take that discussion in three different directions right now.

It's so interesting but I think this is a good moment.

So is it effectively that because it's so site specific, because it's so specific to the river and how it looks like site specific short story, does it mean that we need to have this tool in our pocket that should there, you know something should we detect that on this particular river, you know, it's river, let's say in a sufficiently bad condition that this natural bypasses cannot form and it might cause the problems for salmon and at the same time for whatever reason salmon is still present in that river and the beaver will actually have a negative impact, not theoretically, but practically because their salmons are there.

Then we should take action, either remove the dam, remove the beavers and so on.

So are we effectively talking about this, this need of a like active management scheme?

Yeah, I think, I mean, as you say, it's, it's a topic that can be discussed for a long time.

Just going back to something I said earlier about it might not have been clear, but yes, our rivers are trashed, but I'm not saying that we don't have salmon and important species living in some of these trashed rivers.

So there is, as you say, if you've got a river in a bad condition, is heavily canalized, salmon are still present, beaver dams are going to be more of an issue there than in nice landscapes where the river is connected to floodplain, etc.

So absolutely.

And Beaver Trust has been working, so we've kind of.

Obviously we're not just about beavers.

We want good, healthy rivers, we want to restore beavers because of the benefits that they can bring to biodiversity, to climate resilience, to ecosystem services.

On the back of the beavers unwanted working group, they obviously stated that there needs to be some form of sort of management or something that can be used.

However, nothing was done about that for sort of 10 years.

So Beaver Trust, Wild Trout Trust, Atlantic Salmon Trust, West Country Rivers Trust and Devon Wildlife Trust sort of came together.

We had some discussions about, right, how can we try and tackle this, how can we try and answer this?

It seems to be a big question.

Everyone's saying it's a problem but no one's actually doing anything about it.

So we developed something quite appropriate.

It is called BDAMs, which is the Beaver Dam Assessment Methodology for salmonids.

And it's a pack, ultimately a pack of 30 odd page document and in there is a flowchart of, and this is aimed at not necessarily river experts and fishery managers, but more obviously there's a lot of people out there that work alongside and within rivers that might not necessarily be that sort of knowledgeable on fish.

They live under the water, obviously and they're not necessarily a species that's at the forefront of someone's mind.

So people working with beavers, for example, they might not think about the fish because the beavers are great.

What they do, they can see, they're big, they're furry, they're cute.

So what this ultimately does, it's a method, it's something that someone can physically hold in their hand and it's a flow chart and it takes you through a process to assess a particular beaver dam at that point in time and it will bring you to a conclusion as to whether intervention is required.

And obviously we need to factor in licensing as well because obviously beeves are European protected species.

Dams over two weeks old are protected.

So if you want to interfere with the dam over two weeks old, you need a license.

Obviously there's a few other sort of caveats and things, but I'm not going to go into licensing.

So ultimately, and we've had sort of support and input from Natural England and Environment Agency, so they are sort of happy to recognize its use.

So hopefully in the autumn that this document will be out, we will publish and print a certain number of hard copies.

But equally the plan is to have it as a downloadable PDF on the beaver management website, which is a.

It's a website designed, it's been funded by the government and it's designed to enable stakeholders, landowners, anyone with concerns about beavers, how to help sort of manage or mitigate all or ultimately just where they need to go to get advice.

So contacts within Natural England, whether or is it nature?

Scott in Scotland So, so, yeah, but so obviously when we look at a dam, so going back, when we look at a dam for fish passage, obviously there needs to be a route for the fish to jump or for the fish to swim.

So bypass channel, is that sort of.

That's your sort of perfect solution is a channel.

And generally speaking, if you've got a channel that's 60 cm wide and 20 cm deep, that is sufficient, based on the Environment Agency fish pass manual for an adult salmon to pass.

So we're not looking at massive sort of 2 meter wide channels, they don't have to be huge and obviously they'll be sufficient for pretty much any other species of fish.

If it's suitable for an adult Atlantic salmon, we've got to then think anything smaller than that is more likely to.

But obviously not, as we've just discussed, you're not always going to get bypass channels, are we?

So in these situations, if the dam is low enough, you might get an opportunity for fish to jump.

So generally speaking, anything over sort of 40cm would then be too high a jump for the trout to pass, for example.

So we based the metrics in the methodology on the smaller size.

So 60cm is classed as sort of reaching the upper limit for Atlantic salmon to pass as a clean jump.

But we base it on trout to ensure that if a trout can get past, then the Atlantic salmon can get past.

If an Atlantic salmon can get past the trout, we get past basically.

But in order for a fish to jump a structure, it needs a depth of pull beneath the dam to enable it to sort of gain that momentum to be able to leap.

So one of the sort of management interventions is what we call notching the dam.

So we could go to the corner of the dam or the edge of the dam and retake off a section of that damage and then that will allow the water to flow round or flow over.

And if this is an ongoing management method, what we're suggesting is if you keep doing it in the same, on the same side or in the same place when that water flows around, that will help to scour out the pool below the dam to create a deeper pool to give fish that ability to gain that momentum to help with any jumping.

That's very interesting.

I almost thought that you're gonna say that you're just gonna, you know, dig a little bit hole in.

But you're right, it's good.

Going to be created naturally by the flowing water.

Rob, what are the current management practices around beavers?

Because obviously that's what jumps in my.

Into my hand is like I know that there are already some beaver management, some licenses to.

I don't know, it's probably shooting the beavers or like some lethal control.

I presume these are not related to fish, they're related to impact with human interest, agricultural interest, correct?

Yeah, yeah.

So sort of 99.9% of any licenses that have been issued have been due to sort of impacts predominantly on agricultural land and that sort of thing.

So what are the points?

So that scheme doesn't exist yet to help fish.

This is going to be after you're going to publish this document.

Yeah.

So I mean there have been, there's been a couple of times when a license has been issued to notch a dam for fish passage.

But I think the tricky part of here is actually evidencing it and proving that a dam is causing an issue.

Because if you look at a dam on Monday, the, for example, you could go that's an issue.

Or if you look at it in July, that's an issue.

But come September, October, November when the rains are in, you're obviously that dam is going to change.

Water's going to come around.

Strength of an autumn storm will bash the top out of it and create a flowing water over the top of it that fish can then navigate.

So it's.

I think it's going to be a tricky one.

Um, and that's why I think this, the whole sort of development of the beaver, the B dams is it.

It's a kind of way to help try and standardize it.

And we've also got I think it's kind of a, not, not a double edged sword.

But when, if we feel that we need to intervene at a beaver dam, we've also got to affect, we've got to think right, okay, so we feel that this dam needs notching to allow fish passage.

But you, you only want to notch it to a certain extent because you don't want to lose all the benefits that are upstream with the beaver wetland.

You've also got to consider other protected species.

So our water voles using the area now that in this beaver created wetland.

So if you go and drain it, are you exposing their burrows and that sort of thing?

So it is a tricky one and I think this goes back to species specific, site specific.

Yeah.

You know this is the moment where I worried, I'm worried and this is like a dynamic that develops in so many other areas in conservation that on one hand when let's say there's a hypothetical scenario or maybe not that hypothetical, they were like okay, there's a license, we need to notch the dam or remove the dam or remove the beavers altogether, then there's going to be a proportion of well meaning people who are going to kick up the dust of like oh they destroying beaver dams and like.

And then on the other hand there's going to be proportion of other people like anglers and so on.

Say like you know what, we know that if we need to, I know we have this plan, we need to manage and we can manage but surely you know them, they going to be opposed that therefore we don't want no beavers just in case.

And I think this is like this like unhealthy dynamic.

There's a, there's a possibility of this developing.

Do you do curious your comments?

Yeah, no, absolutely.

And you do see certain groups, certain stakeholders that are concerned about beavers or are objecting to beavers based on what possibly could happen.

We've seen people cutting all the trees down on their patch of land so that there's no trees left for beavers to come in to discourage them.

So I mean you, you get that level of sort of.

Yeah.

Degree of hatred or whatever the word you want to use.

But again I think what needs to happen here is it's the dissemination of knowledge and dispelling myths.

I mean C.S.

lewis, for example in the lion, the Witch and the wardrobe, Mr. And Mrs. Beaver are sitting down to a dinner of fish.

That, that doesn't happen.

It's and from a childhood and these are stories that sort of people grow up with.

It's the Big Bad Wolf.

It's a thing like that.

And there's actually a recent.

There's a recent children's book that's been published.

I can't.

I can't remember the name.

I probably shouldn't say it, but I can't remember it anyway.

But in that, it states that beavers build dams to create it, to make it easier for them to catch the fish in the ponds.

So it's.

And that's what we're trying to do with the research, what we're trying to do with balancing the scales, what we're trying to do with the beaver dam assessment methodology.

What we try to do in this podcast.

What we're trying to do in the podcast is have these discussions.

And it's just, it's.

It's a tricky one.

We.

We haven't lived with this species for 400 years.

I think British people are particularly against change, like to know what's what.

And we manage our landscape.

We like to have management plans.

If that's not in our management plan, then I don't know what to do if it's out of our control.

So I think the good thing about this research that's come out of my work, that's coming out of James's, that's going to come out from other projects, is that we're slowly sort of trying to chip away and just present that knowledge and go, well, look, we've looked at that passage is a question.

We've looked at that and it's going to be different for other species.

But what it's shown is for brown trout in a normal average year, in an autumn and a landscape that is connected to the floodplain, you can see fish passage, but equally in a low year.

So in the year of 2016, you might think, well, but you can use that.

Then we can use that information to go, right, okay.

The weather forecast isn't as it's middle of November and there's no rain forecast for the next three weeks.

We know there's salmon in the river.

We know there's a beaver dam.

Let's go and have a look at it and let's maybe see if we need to do something.

So I think we need to be proactive about it as well.

I think the other.

I think one of the other concerns as well, which I haven't actually touched on, is obviously salmon and trout need clean gravel to spawn in.

So the other concern is that if a beaver builds a dam in a particular place, the clean gravel upstream of that dam will then subsequently be inundated with silt.

So yes, you could have a change there and a potential loss in spawning habitat.

But again, in a river that's connected to floodplain and fish can move, new channels can be created.

And we've seen this in Devon as well.

We've seen a channel that massive dams being created, new channels have been created and after a year or so, that channel is then full of pristine, clean gravel because all the sediment is being sort of caught up behind it.

So you're likely going to see this shift in.

And this would happen in a naturally functioning river, you would have trees falling in.

And this happens in all the other countries that have had beavers that have, where beavers haven't gone extinct.

So it's, it's sort of addressing that.

And again, you might particular location.

If you've got a dam that's sort of covering up gravels, then yeah, I think you need to address that.

But you need to think, well, equally, what, what can we do here?

We need to weigh out the pros and cons.

And I think one of the interesting sort of not arguments at the moment or, but is it's that sort of.

It's an aspect of looking at sea trout.

So sea trout and brown trout, salmo trout, they're the same species, they have evolved to go to sea in rivers that can't support them, which are sort of low in nutrients or food resources.

So you're often seeing the trout coming, they're acting like salmon, they're going out to sea, coming into the roots to spawn.

One of the concerns here is that with the creation of beaver dams and beaver ponds, you're creating a habitat that can support trout within the river.

So there's a concern that you might see a local reduction in fish going out to sea.

So that anadromous population and I think a lot more work needs to be looked at and things like that.

But it's sort of.

But this isn't like this, again, like a human created thing, like, oh, I want this fish to go to the sea.

But if the river can support them and they naturally stay in the river, like what, what's wrong with that?

Well, I mean again from.

This is my personal opinion, not beaver trust or anything, is obviously as a life history strategy, going to sea is a tricky one, it's a dangerous option.

Whereas if the river can support them, then obviously for that fish, for that individual, it's a safer strategy.

Obviously, sea trout fishing on certain rivers economically can be very sort of important.

So we need to factor that in, sort of financial implications, cultural implications.

But ultimately it is a changing landscape.

And are the high levels of sea trout a result, historically high levels of sea trout, is that a result of how bad a condition our rivers are in?

I don't know.

It's.

That is a question because obviously in my, in my study, what we.

We compared two streams that flowed into the same lock.

Obviously one had a series of dams, the other didn't.

And what we were seeing in the stream that didn't was we had a small stream, obviously fish, the mature trout from the lock were coming up, they were spawning in this stream.

But once the fish hit sort of 6, 7 centimeters, that was about it.

Maybe 10 centimeters was the maximum size of fish that that stream could support.

So this is just a sort of a condensed version of sea trout really because they're.

Now what happened with those fish is they would move out of that stream and go into the lock, downstream into the lake, and they would live out their life in the lock before reaching sexual maturity, then coming back up into the streams to spawn.

So it's the same as what's going on from a river into the ocean, but just on a much smaller scale.

But what we found is in the beaver ponds, some of These fish were 25cm.

We were getting a higher abundance of bigger fish.

So it's suggesting that those beaver ponds could support a greater variety of size classes of trout purely due to the food.

That's the greater abundance of food within, the potential shelter from so refuge from predators.

With the overgrown banks, the felling of woody debris into these ponds, you also get more stable water temperatures as well.

Obviously during the winter months that cooling and warming is reduced and during the summer as well, obviously that a small shallow pond is going to heat up a lot quicker than a deep pond.

So you've got all these sort of benefit, beneficial changes, but we have to look at that population as a whole rather than just going, well, there's a reduced number of trout fry here.

Now we're still getting fry.

But are the survival rates greater?

There's research just suggest that the survival rates of fish when beavers are present are higher because of the thing that's been created.

And one of the sort of, just another thing that we found was that in the beaver pond we actually saw growth, sort of positive growth rates during the winter months when you would expect fish not to grow because of.

And this is in the Highlands north of Inverness, so we're talking sort of cold climate.

But during both winter periods, brown Trout within the beaver modified habitat were exhibiting positive growth, suggesting they're also, they're not just surviving but they are thriving.

So it's a very interesting topic and lots of nuances, but yeah, and look.

Like what you're saying, I sort of agree with you.

I think that I tried to say the same thing and obviously I fully understand that we have to be conscious of human interest as well.

Like you said, fisheries and so on and so forth.

But me personally, I'm all for fish choosing whether they want to go to the sea or not.

You know, sort of thing like, well, you know, this is natural process and we here restoring those natural processes.

I don't think we need to look at it as a bad thing.

I think it's again, it's changed.

And there's studies that suggest that as a sort of in contrast to salmon who return to the same river that they're spawned in the sea.

Trout population around Britain has been shown genetically to be regional.

So if a fish leaves River A, it's not necessarily going to come back and spawn in River A.

So the sort of the west country, for example, Devon, Cornwall, fish might they.

They will move around.

So they're regionally, they will come back to the same area, but not the specific river necessarily.

So, yeah, I think if, if the fish can be supported by the river and the habitat that's created, then yeah, I think you then got to weigh up that sort of the biological aspect, ecological aspect and the financial aspect.

It's difficult, huh?

It's difficult and complex.

It's a tricky one.

And I think the discussions will be going on for a while.

But I think, I like to think we're making inroads and we're answering some of these questions, alleviating fear in certain places, maybe raising more questions than others.

But at least if we've raised the questions, we know what we need to sort of look at and try and research.

No.

And for sure, and this is fantastic that, you know, the work that you do and your, and your colleagues, you know, both in academia and in Beaver Trust, this is, this is fantastic because I think there is no question about the positive impacts of beavers.

And you know, I take the results so far as a good news and maybe that's a good moment to just, you know, before we wrap this up, I just want to touch on one more thing because in the film itself there's also mentioned research and similar situation in Norway and in United States and we, we hear often, or at least people who are interested.

It's like you know, beavers and salmon or salmonids, they're co evolved therefore they're built to be in the same habitat, in the same ecological system.

And there was a lot of research done in Norway where there's no problems found in the us no problems found like good things and so on.

And then before your research and before your experiments and before we have this, where we are right now there was often discuss salmon and Samon is in the context of beavers was like oh we have this research there, they're co evolved, they're co evolved here as well.

But then it's like no, no, no, but this is there and we need more research here.

And I got to come out and say like even I thought that you know the arguments of like oh we need to, you know, wait and not do anything until we get to specifically research here was a little bit of a, you know, putting the brakes for a sake of it.

Like you know, like we don't really like beaver around, therefore we're going to say we need more research here specifically rather than in other words taking it from other countries.

So to set the record straight here, like how relevant is the research from other countries to the UK to the waters in the UK and you know how, how much we really need research done locally in the UK and how much of that is there like as an expectation, like well we really just going to confirm the results we already had but we just need to tick that box to have a results from here.

But fundamentally there's same species, same salmon, same beavers, et cetera.

It is a very good point and it comes up in a lot of meetings and it has come up in a lot of meetings for the past 15 years.

The duration of the time I've been working with beavers and fish.

Absolutely there is this feeling or attitude that well no, that was conducted in Norway so we can't use that, that's irrelevant.

I personally disagree with that to the extent that with certain caveats it's fine, you can sort of extrapolate that and you can sort of expect to see those conditions in similar situations.

So in Scotland for example, you would expect to see similar things that's going on in Norway again with those caveats that obviously Norway's rivers, not salmon, Norway's rivers are probably ecologically in a much better condition than the rivers in Britain.

Information from North America, again very different with the caveat that some of the research has been done on Pacific salmon, not Atlantic salmon, so different life strategies, that sort of thing.

So some of that is not transferable.

But again, there's been lots of work done in North America on Atlantic salmon, so particularly demonstrating that salmon, juvenile salmon in beaver ponds have a better body condition than juveniles outside of the beaver ponds.

That is similar to what we found in Scotland with trout.

And not belittling my work because that would be stupid, but we basically found what we expected to find.

The, I mean, the weight gain in the winter, that was really interesting and quite unexpected.

But in terms of the abundance, how they can support greater variety of bigger fish, that sort of thing that was ultimately expected, the fish passage.

It would be expected that a species that's co evolved with a beaver, with beavers for millennia, would be able to pass a beaver dam during high flows.

So you could say it's groundbreaking work from a British context, but it's not groundbreaking work.

It's replicating what's been done elsewhere.

But I guess that's important as well, right?

Like reproducing this study and reproducing results in the different.

It's important as well because now it gives more credibility to say like, well, look at this research over there.

All this matches.

Why would that not match?

Well, it helps answer your question.

There is, can we use data from other countries and ultimately if we're finding the same thing in Norway and Scotland, then it's sort of suggesting that we can.

But yeah, I mean, obviously certain caveats need to be factored in.

And I think one of the other big things which we've touched on multiple times is people often say, well, you can't refer to Norway, you can't refer to North America.

Much bigger landscapes, they're connected to the floodplain.

Our rivers are heavily canalized.

But we're acknowledging the fact that yes, they are heavily canalized and that's going to cause more issues in rivers in sort of west coast of Scotland or wherever where sort of natural processes still happen.

With floodplain connectivity, we can sort of utilize information from other places.

And I think it would be silly not to.

We can't just sort of shut the box and have that island mentality that only research done in Britain is valid when it's not.

Work in Switzerland has come to the same result.

They found the same thing in terms of fish passage and beaver dams.

High flows, they pass low flows can cause issues where management might, then intervention might be necessary.

This is great.

I think that overall we're moving in the right direction and you know, having more data, more information and confirming information that we already had and like you said, giving Credibility to the research done.

Like a much larger body of research conducted in the other things and other places.

And you also can say like, okay, where it might not actually be relevant, which I guess would allow to design the study more specifically focusing on the areas that might be problematic in the uk.

Absolutely.

Context rather than just generally reproduce results that we already have.

I think like so, yeah, absolutely.

And for example, at the beginning when we sort of, we talk about salmonids, but as we stated that trout and salmon have different habitat requirements.

So there's going to be, you can't necessarily use data from trout that will absolutely reflect salmon.

But equally I feel that there's certain aspects of research that you can sort of take into that.

If, if a beaver pond is refuge and a thermal refuge or winter refuge for one species, then is likely that it can act for another species.

The more, the more research we do, the more information we get, the more sort of the knowledge and it's that sort of just again, reassuring people and going, well look, we found the same in Britain as they found in Norway as they found in Canada.

So yeah, I mean, but I think as you say, the benefits of beavers have been so unquestionably demonstrated that and the state that we're in in terms of our climate, I think no, we need to act now, we need to do something.

I'm not saying they're not the silver bullet, they're not the cure all, fix all, but they're definitely going to help.

We need many bullets, I guess with the current situation.

Ro, to wrap this up, what is your view for the future?

If you look at in your crystal ball, how do you see the future of both beavers and salmon?

And you can pick the timescale whether you want 10, 50, 100 years and you can think about globally or maybe in the context in the UK it's whichever you want.

I just want, I know that you're an optimist, that, that I want your, your realistic view on both of those species in their future.

Let's go with beavers.

I think there is a lot of space out there for beavers in Britain and there is still a lot of good for them to do.

There are going to be ongoing management requirements in certain areas as a whole.

I would like to think that they are going to be beneficial with the caveat that intervention is going to be required whether it's notching it down to allow fish passage or whether it's protecting trees or that sort of thing from felling, protecting crops or orchards, that sort of thing.

But no, I foresee a fundamental change.

There's lots of other things that need to be fixed, but if we can fix them sort of alongside the presence of beavers, then I can only envisage an increase in biodiversity, a sort of a more resilient landscape to drought, a more resilient landscape to sort of flash flooding.

In terms of salmon, it's a tricky one because there are so many factors affecting salmon.

So obviously global warming, changes in sea currents, overfishing, salmon farming.

I'm not sure how to answer that in terms of them because I think there's so many unknowns.

But I think all we can do at this point is make our, put our river, fix our rivers, put them in the best possible condition, allow the juveniles to thrive in our rivers before going out to sea and just try and maximize their chances of returning.

There's also a plea to the powers above in the terms of this needs to be addressed.

Certain sort of salmon farming practices need to be dealt with.

We need to find out what's happening at sea, we need to stop the overfishing, that sort of thing.

And it's a big plea and no one's going to listen.

But I think that's where it needs to be in order to save the species.

And I'm not saying beavers are going to do it, but could beavers be a factor in helping salmon in maybe is in certain areas then I think it's worth giving them a go.

No one's proven that they are detrimental.

We've shown that they can coexist and they have coexist for millennia across the northern hemisphere across multiple different species of salmon.

So let's, let's, let's give it a go.

That's, I mean, yeah, I think this.

Is like basically whether be there's are this one, you know, one, one more cut that is killing the salmon or maybe this is, this is one more thing that is helping them.

And you know like as we, as we well know like you do what you can, you, you, you're not gonna worry about what you can't do.

Do what you can do and have that impact.

And if we know that this is like a little thing that will actually help Simons and Samonids rather than be detrimental to them.

Let's do that and have all the, all the benefits alongside that.

Rob, thank you for that.

That was great and great.

Great piece of research folks.

Balancing the Scales is the title of the entire documentary.

It's gonna be available you said in October on beaver trust on that website.

Yeah.

October, I don't know.

I can't remember the exact date.

I'm sure I'll get told off for that.

But it's it will be on The Beaver Trust YouTube channel in October.

There are also two other videos on there about beavers and our landscape.

So beavers, Beavers Without Borders and On the Edge and they sort of address different sort of topics as well if they're of interest to any listeners.

And we're going to put the links to those in a, in a, in a show notes and folks if you want to you know keep, keep in touch with information, you know, when, when a public premiere is and stuff like that, you might subscribe to my newsletter newsletter.thomas outdoors.com the link is in the description of the show as well as all the other links to the websites and research we mentioned in this episode.

Rob, thank you very much.

It's been pleasure talking with you.

No, thank you very much indeed.

Been a pleasure to join you.