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East Anglia’s work protecting eels

Posted by: , Posted on: - Categories: Environment Agency

My name is Dan Hayter and I work in East Anglia for the Environment Agency.
Part of my job is monitoring and protecting European eels which are a critically endangered species.
Eels are born in the Sargasso Sea in the north-west Atlantic Ocean. From there, they float in their larval form on ocean currents towards Europe – journeying over 3,000 miles for up to two years. Once they reach the coast, they turn into transparent glass eels (up to 8cm long) and then elvers (up to 12cm long) swimming upstream into rivers. Here they live for around 6-10 years as juveniles/sub-adult (yellow eels), before swimming downstream and eventually returning to the Sargasso Sea as mature adults to breed (silver eels)

At the Environment Agency we are working hard to address the struggles eels face and protect them.
We know barriers, weirs and sluices are problematic as they disrupt the natural flow of rivers and can prevent or slow the migration. These structures are designed to control river levels and prevent flooding so my task is to monitor them and improve migration for the eels to overcome these barriers. Loss of eel habitat is another big factor, with rivers historically being less natural with less wetland and floodplain connectivity. To mitigate this the Environment Agency designs and installs eel passes to help eels get from the sea into the freshwater habitats and then back again as adults. We monitor sites to ensure eel passes are maintained in good condition and are effective throughout the migrating season.

The Environment Agency is involved in many natural flood management projects which reduce flooding for people but also improve the habitat for the eels whilst improving biodiversity.
Pumping stations can be very damaging to eel stocks. We ensure that the owners of them help protect eels by installing screens to prevent eels entering. We make sure the screens are regularly inspected and maintained by the owners. We also carry out maintenance on our own eel passes and screens.
As a result of the decline in eels over the last 40 years, the environment agency carries out eel surveys where we monitor the different life stages (glass eel, elver, yellow and silver eel).

We have elver monitoring passes where we can count the numbers that swim through each season. The data gathered is combined with other records from around Europe to monitor the overall population and to help with future management. When we carry out eel surveys we also check their health and look out for parasites and diseases. If we suspect disease in a population, we can collect health samples which are passed on to our laboratory where specialists will investigate the cause and also help with future conservation.

We know that stress in eels can result in mortality. Stress can be caused by many factors such as migration issues, loss of habitat, drought, health problems, illegal trade and fishing. The Environment Agency protects and improves fisheries and invests a great deal in improving the environment and conditions where eels live. This along with all our eel specific work, reduces the impact people have on eels and this will in turn reduce stress and disease.

Another major challenge we are facing when it comes to protecting eels is climate change. Changes in ocean temperatures and currents can interfere with the migration of the eels and can affect how they breed. We know they breed in specialised conditions at depth in the Atlantic Ocean and any significant changes could be a big problem. With climate change we are also seeing an increase in the number of storms, which could affect eels by disrupting their incredible migration. The work we do will give eels a much better chance to cope with the environmental changes that are likely and, by continuing to learn about these fish, we can adapt and improve what we do in the future.

Eels are an important and fascinating species inhabiting our water environment. They feed on various things including invertebrates, fish, molluscs and crustaceans, helping to recycle nutrients and they are an important food source for many species. If members of the public are interested in our work with eels they can check our website, blog and look at our data.

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  1. Comment by Julian Jones posted on

    You do not mention contaminant pressures on Eels; toxic farm chemicals primarily. These were widely held to be the major cause of eel mortality & catastrophic declines in returns, coincident with the introduction of these unregulated toxins, prior to Eels Regs/Directive - which oddly also make no mention of these.
    We've long had impoundments - not that much of an impediment to elvers; used to see them glistening in their millions as they traversed, up and over these, on some early mornings here on Severnside.
    Climate change is a shocker - scary amplification going on now. We've seen river temps increasing by greater factors than oceans during during past century. Land use again - farm chemicals (arable & livestock) aridifying and destroying microbial soil respiration etc ...

    • Replies to Julian Jones>

      Comment by Anthony Richard Camplin posted on

      It doesn't how much you improve the rivers if the eels aren't there in sufficient numbers it won't help. There used to be literally millions of elvers coming up our rivers and many of them were harvested for food. Hopefully this practice has now been banned. What's needed is some way of catching the elvers at sea and introducing them into the river systems. It's a shame that they can't be artificially reared, maybe one day?

    • Replies to Julian Jones>

      Comment by Chris Greasley posted on

      I think many state funded organisations regard agricultural pollution as an inconvenient truth. I would be sorry if mention of such was avoided in scientific analysis for political reasons although it was ever thus and the behaviour of some senior academics in bowing to such pressures causes me to despair.

    • Replies to Julian Jones>

      Comment by Terence James Lambourne posted on

      There is a more important factor involved. The BIGGEST contributor, to Ocean warming, are those, ruddy great big gin palaces, called Liners. These ARE afloat, with MANY , sometimes, people on board . I am an Ancient Old Fart, of 87. For MANY years, I have fished Southampton water. From Hythe side, before the marina was built, Town side, and at Marchwood. I have, also,
      been to the Cunard Wharf, to deliver people, for cruises, and to collect them, on return. At NO TIME, have I seen a Lighter alongside, NOR a rubbish /Refuse Lorry, collect waste, from the gin palaces. They dump it, straight in to the Briny. Along with, Many cubic yards, of EXCREMENT, and Empty Wine bottles, which are smothering the Flora, which feeds the fish. NO newspaper will print this, I have tried, because of the VAST incomes, derived from Advertising. I have TRIED to contact Greenpeace,vut they HIDE there site. ZSee what YOU can DO. Cheers, Terry L.

      • Replies to Terence James Lambourne>

        Comment by Richard Dahle posted on

        I have a water local to me where if you go fishing with garden worm you will catch eels all night long some of them are a good 3 or 4 foot long

    • Replies to Julian Jones>

      Comment by terry Lambourne posted on

      There is one BIG contributor, to Global Warming. Those dirty great big Cruise Ships. The DUMP everything, straight in to the Briny. How many MILLIONS, of WINE Bottles, are covering, the Ocean Floors, along with Sewage, and Rubish ??.These liners, are Driven by Massive Diesel engines. They Need Many TONS, of Water, per day, to cool them. Also, many TONS of water, per day, are used for Hygene, and Cooking, and Dumped in to the briny. UP goes the Ocean Water Temprature.

  2. Comment by Ian posted on

    And of cause the sudden huge population growth of otters whose favourite food is eel.

    • Replies to Ian>

      Comment by Richard Miles posted on

      Eels and otters have co-existed for millennia before something else, can't think what, disturbed the balance of nature

    • Replies to Ian>

      Comment by Norman Nash posted on

      Otters are a natural predator and are a part of a healthy river eco system .

    • Replies to Ian>

      Comment by David Goodwin posted on

      & don't forget the impact of huge numbers of Cormorants

    • Replies to Ian>

      Comment by Mark Eyre posted on

      Ian ,
      If you are a keeper of Koi, chikens or a fishing lake I sympathise....however ,
      Lutra lutra has been coexisting with the eel since the Ice age. Sure otters love to eat eels, trout ,salmon, chickens etc and until the 1950's , despite their status as vermin, they prospered as did their prey. DDT initially thwacked otter numbers but its removal and the cleaning of industry during the 70's and 80's found them as common as ever. There has followed an intensification of agro/urban chemical inputs and abstraction . The otter persists, it's adaptable, its prey ( apart from chickens and carp ,perhaps) is not.

  3. Comment by Andrew Neil posted on

    You fail to mention that eels are the favourite food of Otters that have been haphazardly released into our waterways with no though as to whether there is enough food for them

  4. Comment by Graham Bissett posted on

    There have always been otters, just as there have always been eels, and, as we know, nature will always find a balance. The bogeyman in that balance is the human being. I've been an angler for 60 years, and have no problem whatsoever with the return of otters to our rivers. We have to learn to live with them.

    • Replies to Graham Bissett>

      Comment by Alan Davies posted on

      Did you see the damage otters did to the once great river at Adam’s Mil the home of the British barbel? Well I did. Otters completely upset the eco system of that stretch of river.
      I saw thousands of roach all huddled up together. Frightened out of their lives. I saw fifty chub in open water with nowhere to go because the barbel had taken all the safe spots away from them trying to get away from the killer otters that the stupid Natural England introduced into this prime stretch of river. The otters eventually killed the British record barbel.
      I’ve been an angler like you for 60 years and I’m telling you these nasty creatures should never have been re introduced back into our beautiful rivers.

  5. Comment by Colin staples posted on

    Eels are more valuable than otters as we can eat eels have we banned export of elvers from Somerset levels etc
    70 years ago eels were plentiful in the itchen even professional fished by quoting very sorry what has happened to them please key up good work

  6. Comment by David posted on

    Am I correct in thinking glass Eel fishing is still allowed on the Severn? Critically endangered fish harvested in their thousands for profit when an angler can be prosecuted for harming an Eel he/she has caught?
    As Ian says,Otters are another problem,Eels are their favourite prey.

  7. Comment by Rob posted on

    Can we not harvest quantities of elvers and translocate them to freshwater ponds. I remember in the 60`s ,in my youth ,the local ponds were full of eels.

  8. Comment by Steve posted on

    Well said Ian, unfortunately nobody including the so called environment agency wants to own or even acknowledge this destructive introduction to the British waterways on mass.

  9. Comment by Neil Wheater posted on

    Pollution is the main problem for not only fish but all river life,while the water authorities are permitted to dump sewerage in our once prestine
    Rivers fish stocks especially eels will continue to decline.

  10. Comment by R Spalding posted on

    What is the best way to release an eel if it is caugth on a hook whilst fishing for other species? They usually swallow the hook very far down their throat.

  11. Comment by Henry Hansen posted on

    You make no mention of the netting that you sell permits for. How can this be allowed given the perilously low amount of elvers that return to UK shores ? What revenue do you generate in these permit sales ?

  12. Comment by Reg Griffiths posted on

    Just a shame that the EA is scared to prosecute the water companies that heavily pollute our rivers. A dog with no teeth !. Or does profit dictate prosecutions?.

  13. Comment by A .M. Eyre posted on

    Thank you for an informative piece. Please keep up the good work. Big Tea.

  14. Comment by Chris Podd posted on

    you could of course ban all commercial eel fisheries especially in the Bristol channel . I dont know if it still goes on but I didnt think it was a good idea using British elvers to restock European rivers or send them to Japan for human consumption !
    Of course this may not still go on ?

  15. Comment by christopher godden posted on

    Yes I think careful consideration should be given to the increase in the otter population. This is something that The Environment Agency should monitor and implement culling if required to keep the correct natural balance.

  16. Comment by H. Turner posted on

    Have seen otters often eating eels as well as taking young birds and their eggs.

  17. Comment by Chris Ellis posted on

    I’m surprised you don’t mention pollution. Our rivers are in a terrible state with run-off from farms, industrial waste, sewage and micro-plastics. Surely this is easier to tackle than climate change?

  18. Comment by Mike Greenwood posted on

    Are we still licensing people to trap and net elvers? Surely this has to stop immediately.

  19. Comment by Michael McTernan posted on

    Not a word about the Elver fishing, especially in Somerset. Are the netsmen also a protected species.?
    Also, are there similar actions being taken in Europe, as smoked eel and boiled eels are considered a great delicacy in Holland and Germany.

  20. Comment by davedhh posted on

    do the rivers still get dregded

  21. Comment by Brent Smithers posted on

    Very pleased to see there is research going into eel numbers and protection. However I am very surprised that there are no mention of the numerous sewage discharges into our rivers and seas. Surely these must have a hugely detremental effect on eel numbers and progress up and down rivers???. Does your research provide any evidence as to how these discharges effect eel numbers?

  22. Comment by Ken Reynolds posted on

    Poor management of weirs and sluices doesn't help. Some in my area haven't been operated for years so they run at same level all year. Used to catch a few years back but haven't seen one for ages.

  23. Comment by Peter Cocker posted on

    So! what do you want, ells or otters?

  24. Comment by Michael Cowburn posted on

    Over-fishing i n the past has probably been a factor.

  25. Comment by Atkinson posted on

    We use to have quite an healthy population of eels on the river ure at ripon including lamprey and sea lamprey but the introduction of Large numbers of otter they are no longer present .
    Sea lamprey were only found in 2 rivers on England and more endangered then eels so you have to ask the why the environment agency found this otter programme when they must have known the outcome.

  26. Comment by Jamie Green posted on

    The eel is an amazing species a couple were known to have been caught from the Thames and introduced into a local freshwater lake in the mid eighties where carp fisherman were catching them on fishmeal boilies in the nineties releasing them safely and at a much improved weight and size

  27. Comment by eric meadows posted on

    Unatural preservation of predators
    such as Otters Cormorants and Seals etc
    is what is causing the decline!

  28. Comment by Bob posted on

    As eels were known to have existed in the cretaceous period 145 million to 66 million years ago and have survived 8 bouts of climate change in the last 800,000 years we can be sure that they will adapt and survive the current changes as will most of the earth's flora and fauna. What will kill off eels and others is human greed by overfishing, destroying habitat etc

  29. Comment by Alan Cattermole posted on

    I have just read the article on eels did not no anything about them till now i would likely thank all concerned for the work you do for protecting them Thank You All Alan Cattermole

  30. Comment by Collin Sampson posted on

    Are people still able to fish for and collect Elvers ? If so, banning this might help.

  31. Comment by The Fortean Dentist posted on

    You have given reasons for a reduction of returning elvers. Once in rivers and lakes they can be predated. What animal could do this? Surely not those cute furry little otters? They would NEVER eat an endangered species just because it is highly nutritious and incredibly easy for them to catch. They have such lovely anthropomorphic faces. Tarka would NEVER do such a thing. How dare those evil anglers blame Tarka.
    Alternatively you could grow up and face the facts, however unacceptable they may be to the "Fluffy bunny vegetarians" Let's face it who are the armchair ecologists going to favor, sweet furry mammal, or nasty slimy eel?
    That is a lost battle.

  32. Comment by Les Everett posted on

    Hi , I have fished Norfolk rivers for 70 years and the seas around our coasts and have seen the decline in our rivers from pollution the increase in otters and seals not only on our coasts but now the rivers.Also a major problem in sewage in our rivers, they used to be pristine but I feel those agencies that are supposed to not only look after our rivers but to remove fallen trees and cut the weeds not to mention helping trout and salmon in our rivers plus other species, when I was younger the rivers were cleaner there was an abundance of fish , the weeds were cut every year, trees were removed plus no sewage ,farmers did not allow fertiliser in the waterways , the otter hounds controlled the otters and seals were controlled, now everyone seems to be pleased to see all this happening without the understanding of the consequences.
    I understand it was a balancing act years ago but now unless we do something drastic it will never recover to the levels I have known in my lifetime.
    This is how a keen trout and sea fisherman feels about today.we have gone back to before Victorian days.

  33. Comment by Duncan posted on

    There is no evidence that the eels return to the place they hatched. The eels leave the Mexican gulf and some float to Europe via the Gulf Stream and some go north hugging the coast and live a similar cycle to our eels but these have been tagged and have been seen to return and breed. This is where focus is needed- in North America as our eels unfortunately are highly unlikely to return and breed where as these do

  34. Comment by Ian Hayes posted on

    Why is the catching of elvers still allowed when eels ate so endangered? Especially as the market is abroad including Russia and not a large domestic market anymore. The licences for export need revoking and native catches limited. I appreciate a few may lose their jobs but the loss of Eels is more important.
    Action now please

  35. Comment by John Laughlin posted on

    Quite recently in the West Country elvermen and others have been transporting glass eels to various sites on various rivers. Does the EA sanction these fish movements?

  36. Comment by ian spencer posted on

    The eel population seems to be increasing on the middle Severn, as every time we fish we meat guaranteed to catch a couple and we have given up fishing the Wye with meat due the amount of eels caught.

  37. Comment by Roger posted on

    Is the netting of elvers for food still allowed on any UK waterways? e.g. along the Severn. A questionable delicacy, which must be very destructive to eel migration.

  38. Comment by nigel smith posted on

    Its not otters though they wont help the few thats left,far too many of them introduced too soon.Seen elvers climb "impassable"structures no problem,reckon overfishing(commercial)probably one of the main reasons.Shame as they saved a blank on a tough day,good fighters as well.(bigger ones).
    Hope it gets sorted,rivers need them.

  39. Comment by Ian posted on

    Caught a huge healthy adult well on the River Severn last summer at Coalport haven't seen one since night fishing on the Avon over thirty hrs ago when they were plentiful

  40. Comment by Roger Eames posted on

    Why do we still allow elves to be netted for food? Surely this practice should be outlawed.

  41. Comment by Dave Gladwell posted on

    And will the Eels thrive in the many places you let Water Authorities go virtually unpunished for discharging sewage effulent? I fear not - and bottom feeders obviously suffer the greatest concentrations and ill effects - meanwhile the Water Authority Management structure will continue to receive sky-high salaries and MBE's in place of the Dismissals and Prison Sentences they deserve!

  42. Comment by Gerald Bradley posted on

    Very interesting topic and informative.

  43. Comment by G posted on

    The more eels the better, as that could mean greater availability of delicious smoked eel from U.K. waters. There's a smoke-house not too far away from here that has to use eels from New Zealand to make its smoked eel fillets. Shame that we don't see eel farming the way we have salmon and trout farms...

  44. Comment by Alan Shinton posted on

    The biggest threats to our fish stocks is the illegal sewage discharges but the Utility companies.

  45. Comment by Peter Westcott posted on

    What about the netting of young elvers returning to the River Severn for example ?

  46. Comment by Roger posted on

    Another tragic story of mans destruction of environments and the impact of this on aquatic life in all forms. Must we wait to act until MPs are fleeing the House of Common due to the stink of sewage in the Thames as in 1858.

    The Thames Purification bill, proposed by future Prime Minister Benjamin Disraeli, became law in just 18 days. 'Almost all living things that existed in the waters of the Thames have disappeared or been destroyed,' he said. 'There is a pervading apprehension of pestilence in this great city.'

    They say history repeats itself and sadly we are repeating the mistakes of the past.

  47. Comment by Stephen Toitz posted on

    The otters cannot be responsible for eating all of the eels and they don't belong to a multi-national corporation of otters who would make it known that otters were not responsible for any eel mortality at all and they would defend that by slapping non-disclosure orders, court orders to prevent journalists from publishing such things about otters as well aggressive court cases rebutting such assertions by hiring expensive teams of lawyers. You would be toast, Ian, for saying such things where otters could fight back. I used to fish for eels in the 60's and 70's and there were tons of them, guaranteed to catch an eels every cast virtually. There has been a catastrophic collapse of the eel population, along with other species such as salmon and sea-trout. The River Wye, a magnificent river with loads of species is being polluted by farmers with chicken manure and assisted by the woeful underinvestment in sewerage treatment and water abstraction. Add to this 50% cuts in the Environment Agency who police the polluters and you have a terrible starting point before even thinking about climate change. I have all but given up fishing these days.

  48. Comment by Michael Price posted on

    Amazing work the Environmental Agency are doing to protect the eels well done

  49. Comment by senior fisherman posted on

    Maybe the 72billion litres of sewage Thames water have pumped
    into our lovely River Thames since 2020 has something to do with it.
    The Government do little to nothing while our rivers are poisoned.

    I have noticed the decline in fish numbers over the past years also.

  50. Comment by John Waring posted on

    Does the Environment Agency have licence to reduce cormorant levels?
    I live in Chester, and see them diving and gauging themselves on fish in the River Dee, Shropshire Union Canal and the many meres throughout the county all the time, as well as neighbouring Shropshire.
    They typically drown dive with eels in their beaks several times to incapacitate/ drown them before devouring these protected species.
    Eastern Europeans also catch to kill, which I have previously reported to the EA.


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