From a boy who fished with a stick and string, our restoration manager Dr Rob Needham has spent his life fascinated with wildlife. That path led through Norway’s lynx forests to Britain’s first official beaver project—and, at last, to a PhD that’s providing vital evidence to fill long established knowledge gaps on the impacts of beaver activity on salmonids. Fresh from his thesis being published, Rob shares the relief of finishing, the thrills of boat-netting beavers by night, and why he believes we can have healthy populations of both Atlantic salmon and beavers in our rivers.
How does it feel to have completed your PhD and have your research on beaver and trout out in the public domain?
“It’s a massive relief to have finally finished the PhD. It was a long time coming, but I got it over the line eventually! It’s fantastic that what took so long is now out there, hopefully providing evidence and facts to answer the many questions about the impacts of beavers on fish, particularly migratory ones. I hope my work will address at least some of those concerns and perhaps alleviate them.”
Tell me about one of your earliest memories in nature and how that affected your choices as an adult. Did you grow up surrounded by animals?
“I’ve always been interested in wildlife. As a kid, I asked for bird books for birthdays and Christmas. I’ve been collecting skulls and bones—much to my parents’ dismay—for decades now. I grew up in the countryside with pets—dogs, cats, chickens. My mum’s side of the family are farmers, so I’ve always felt connected to livestock, open fields, and woodlands. I’ve also been a keen fisherman since I started with a stick and a bit of string at four years old. I didn’t catch many fish then, so I spent more time watching the birds and wildlife around me.”
What did you study at university?
“Some might say I was an eternal student. I completed a National Diploma in Wildlife Management, then earned a Bachelor’s degree in Wildlife Management, followed by a Master’s in Ecology, and finally—of course—the PhD.”
You spent a number of years in Norway working with capercaillie and lynx, how did you end up there and what did you do?
“Near the end of my bachelor’s degree I was able to secure a month-long placement in Norway, which grew into two years with the Norwegian Institute for Nature Research (NINA). I felt very lucky to work with such charismatic animals.
The capercaillie study was research focused on monitoring leks, counting birds, and trying to establish territory sizes through GPS tracking tags. We would head into the forest the night before, just as they went to roost, and set up camp—if you can call it a ‘camp’. We didn’t use tents, as those would scare them. Instead, we found a suitably low branch, laid your reindeer rug and sleeping bag on it, and went to sleep. Mist nets at dawn let us catch males, fit radio tags, and track their movements around the lekking sites and the wider boreal forest.
The work involving lynx and wolverines was focused on predation behaviour. We radio-collared lynx and using the information this provided located their kills. Prey species were recorded and when sheep or semi domestic reindeer were involved, this information would feed back into compensation schemes. We also tagged roe deer—their main prey—to estimate density and movement. In summer months we used the radio collar data to find female lynx dens, where we weighed, sexed, and measured the kittens to assess reproduction, which would provide information on the overall population and rate of growth.
Wolverine work meant even more walking: their vast ranges kept us on the move constantly. I never saw one, but found lots of their poo, hair, and day beds, and sometimes you would find that they had been scavenging on recent lynx kills. It was an absolutely unforgettable experience trekking across the Artic tundra in the land of 24 hour sunlight.”
So how did you end up working with beavers?
“I applied for a position with the Scottish Beaver Trial but didn’t get it—it went to my Norwegian friend Christian. While I was back in Norway, I received a call inviting me to visit Scotland. I met with Dr Roisin Campbell-Palmer, was offered a job, and began working with beavers. It was a fascinating chance to join the first mammal reintroduction in Britain, especially after seeing beaver dams and habitat changes in Norway. The rest, as they say, is history— fifteen years later, I’m still working with beavers.”
Can you think of a favourite moment working with beavers?
“I think my best moments with the beavers were at Knapdale during the research phase. We had to trap them to record body weights and other data, and our main method on the lochs was to head out at night in a boat with a spotlight and a large net, then leap from the boat onto them. It was really exciting—and the other wildlife you see at night is amazing: otters, big trout and eels when shining the torch into the water. The highlight, though, was catching the first wild-born beaver in the Scottish Beaver Trial—Logan, as he was later named. That was pretty cool.”
Your research is one of the first pieces of work in Britain to investigate the impacts of beavers on brown trout. What were the main findings and is there anything that surprised you?
“In beaver-modified habitat we found a wider range of trout age-classes, including much larger fish, suggesting the new habitat supports more life stages. Trout body condition there was also higher than in our control stream. We couldn’t compare growth rates directly because too few fish were recaptured in the control, which offered good spawning habitat but forced juveniles to leave once they reached a certain size. During two consecutive winters, trout in beaver ponds grew above the published ‘optimal’ rate—perhaps thanks to extra food or the ponds’ stable temperatures. Whatever the cause, the data clearly shows that beaver landscapes can provide excellent overwintering habitat for brown trout.”
“One unforgettable moment came while reviewing 10,000 camera-trap images for an additional study where we were investigating the influence of beaver modified habitats on piscivorous (fish eating) predators. I nearly skipped past a blurred shape in the grass, then realised it was a black stork—a very rare migrant—likely drawn to the beaver-created wetlands. Discoveries like that made the whole PhD an incredible experience.”
Anglers and fisheries managers sometimes worry about beaver damming blocking access to spawning areas. Is that something you looked at during your PhD?
“A key part of the study was microchipping almost 1,000 trout—about 700 of them larger adults—and tracking how they responded to beaver dams during the spawning season. Passage rates varied: in high flows many trout crossed the dams, some making several trips, and fish that succeeded once crossed dams faster on subsequent attempts, perhaps having learned the best route.
We had two contrasting years—one with average rainfall and one with very low rainfall and freezing temperatures. In the dry year dam-passage dropped sharply, yet the number of trout on the spawning gravels above the beaver ponds stayed the same, while numbers in the control stream fell by 60 %. This suggests the ponds could potentially act as buffers, enabling resident fish to move upstream to spawn during low flows. The data also highlighted that larger and more motivated individuals are more likely to pass the dams.
The ponds effectively behave like miniature lochs—isolating fish during sub optimal environmental conditions but reconnecting populations when flows rise.
Increased body condition of trout was also observed in the beaver modified habitat, which has has been linked to higher survival in salmonids where this has been found elsewhere.”
What reactions have you had from that community to your findings?
“There have been many positive responses—and some negative ones—but it’s key to remember that this is a nuanced, site-specific topic. Our existing rivers can benefit from the presence of beavers: the dams they build create a mosaic of habitats, ranging from still pools and standing water to faster-flowing reaches over gravel. The different substrates in these zones nurture a rich variety of aquatic plants and invertebrates, and that biodiversity echoes all the way up the food chain.”
Having healthy populations of both beavers and Atlantic salmon in our rivers; dream or reality?
“I think it could absolutely be a reality. Take the River Tay. For more than a decade people worried that beavers would negatively impact Atlantic salmon, yet the general view now is we are seeing very little overlap. Salmon spawn mainly in the main stem, while beavers dam small tributaries and ditches. After twenty years, the Tay supports Britain’s largest beaver population—and 2024 still delivered the river’s best run of returning salmon in a decade, including record numbers of large fish—a hugely encouraging sign. At Beaver Trust we’re starting to see if we can test whether the same pattern holds in other catchments.
Beavers and salmon already live side by side in Scandinavia and North America. Yes, some areas—especially the tightly constrained rivers of southern England—may prove trickier, but with smart management, targeted mitigation, and genuine cooperation among all stakeholders, successful coexistence is well within reach.
Problems will crop up—our rivers are so heavily modified that weirs and fish passes can look like ideal dam sites to resourceful beavers—but plenty of management and mitigation tools are available. The vital step is collaboration: beaver teams must work closely with fisheries.”
Over the years, has any one lynx, capercaillie, beaver or particularly feisty trout etched itself into your memory?
“In terms of lynx, the first capture I was involved in was a male who was named ‘Rob’, so he stands out—I still have his photo on the wall. I remember many of the animals’ names and radio-collar numbers and remain awed by their habitats: some territories exceeded 1,500 km², overlapping several females, and even in the south of Norway they spanned 200–300 km².
Trapping capercaillie and sleeping in the boreal forest among wolves and lynx was another unforgettable experience.
Another moment that stays with me took place high on the Arctic tundra. We spotted a dead female reindeer and went over to investigate. Lying alongside her was a calf, still alive but bewildered. A local volunteer recognised the ear-marking and could identify the owner, so we lifted the calf and carried her some 30 kilometres off the mountain so the reindeer herder could hand-rear the calf.
I feel extraordinarily fortunate to be paid for work others would gladly fund themselves—whether helping with the Scottish Beaver Trial or working for Beaver Trust. It’s been a privileged career so far—long may it continue.”
You’re now a leading expert in beaver restoration, particularly in beaver-salmonid interactions, what is on the horizon for you? Where do you see yourself in ten years?
“I’ll probably still be working with beavers—and, I hope, fish. After fifteen years it feels too late to leave them behind. Ideally, I’ll keep focusing on beaver–fish interactions. Many challenges remain, especially in the heavily modified rivers of southern England.”
If not beavers, what would you be working on?
I’m very fond of the mustelid family—badgers, otters, pine martens—so working with pine martens would be brilliant. Large carnivores like bears and wolves fascinate me as well, but I wouldn’t say there’s one single species I would like to work with instead of beavers.”
What advice would you give to anyone wanting a career conducting research or working on-the-ground in conservation as you have across Scotland and Norway?
“I think the key is persistence—don’t give up. It can be hard to get your foot in the door, so keep sending emails and asking for work experience, and don’t be too fussy: if an opportunity arises, grab it.
This is a tough industry with high expectations and little money, so determination counts. You must be willing to get up at 5am, sleep in the snow, or stand for weeks in West-Coast rain. Know what you want, stay persistent, and don’t be afraid to ask for help.”
You can read Dr Needham’s published papers on the ‘The response of a brown trout (Salmo trutta) population to reintroduced Eurasian beaver (Castor fiber) habitat modification’ here and ‘The impact of reintroduced Eurasian beaver (Castor fiber) dams on the upstream movement of brown trout (Salmo trutta) in upland areas of Great Britain’.
You can also learn more about Rob’s research and its findings by watching our latest documentary Balancing The Scales which explores the delicate balance between beaver restoration and the conservation of migratory fish populations. You can register to host a private screening of the film for FREE now by contacting info@beavertrust.org.
Rob also undertakes semi and fully quantitative electro-fishing surveys in a variety of habitats which are tailored to specific requirements as part of his work at Beaver Trust. Contact restoration@beavertrust.org for more information.