British rivers once teemed with eels but each year fewer make the 5,000km trip to get there. Jon Henley reports on the fight to save this unique creature from extinction

There are six of them, writhing lazily at the bottom of Darryl Clifton-Dey’s plastic tank. “Weird” doesn’t, frankly, do them justice: small, beady eyes; big ugly snout. Sinuous, slimy; even on a sunny morning on the banks of the Thames, faintly sinister. Beasts of legend and bad dreams. Even lightly sedated, one half-hearted wriggle and they slide effortlessly out of your grasp, a powerful ripple of grey-green and silver. Their skin is extraordinary, like liquid velvet.

It’s not widely known that Sigmund Freud’s first job as a scientific researcher was trying to find the testicles in eels. He didn’t find many, because what he didn’t realise was that eels don’t acquire genitals of any description until they need them -- and frustratingly for the father of psychoanalysis, that wasn’t the case with the ones he’d got.

For there’s nothing quite as slippery as an eel. For centuries, we hadn’t a clue what they were or where they came from. Aristotle surmised they were born “of nothing”. Others swore eels were bred of mud, of bodies decaying in the water. One learned bishop informed the Royal Society that eels slithered from the thatched roofs of cottages; Izaak Walton, in The Compleat Angler, reckoned they sprang from the “action of sunlight on dewdrops”.

More than three centuries later, much about them remains a mystery. One thing, though, we do know: the elvers, or young eels, that once wriggled their way up Britain’s rivers in such multitudes that on the Thames alone, as one author wrote in 1902, “they made a black margin to the river, on either side of the banks”, have stopped coming.

Scientists estimate that across Europe, elver numbers have now crashed to barely 5% of their 1980s levels. With no action, it’s feared, in 20 or 30 years there may be no adult eels left either. The European eel, anguilla anguilla, is the subject of urgent legislation in Brussels; it’s an endangered species, and member states are required to take immediate steps to protect it.

This month (OCT), for the first time ever in the UK, the Environment Agency imposed a temporary ban on all fishing for mature eels, declaring a six-month closed season in England and Wales. Fishing for young eels -- elvers and the even smaller glass eels -- is being similarly restricted. Tough regulations now apply to the kind of nets used, their size and location. And Robin Hackforth, a Lincolnshire eel man, is worried he’ll be out of a job.

“I’ve been eel fishing for 42 years and I still love it,” he says. “I still get up at 3.30am, my heart still pounds when I lift the net and see them, all sleek and glistening inside.” Hackforth remembers when London’s Billingsgate fish market sold 20 tonnes of eel a week. Unlike the Dutch, the Germans and the Scandinavians -- unlike, certainly, the Chinese and the Japanese -- Brits may not eat much eel these days, but it was once a staple.

Eels were once so common as to be a form of currency: the Domesday Book lists hundreds of water mills whose rent was paid in eels, or “sticks” of 25: 2,000 eels to “Giles brother of Ansculf” in Datchet, Bucks; 1,000 sticks from Bottisham in Cambridgeshire.

In 1087, the river Ouse alone yielded a staggering 52,000 eels. Nor were they just for the poor: the Bishop of Lichfield and Coventry, on the Feast of the Assumption in 1461, offered his honourable guests eels alongside salmon and trout.

As late as 1853, a London diarist recorded that the city “teems and steams with eels, alive and stewed; turn where you will, you will see hot eels smoking away”. Jellied (chopped, boiled in stock, allowed to set), they’re the Cockney national dish. Today gourmet London restaurants offer smoked fillets, rich, sweet, firm of flesh and high in vitamins and proteins.

And now fishing for eels has been banned (or at least, suspended). The fishermen don’t get it. “Not so long ago,” Hackforth says, “I caught a tonne in four days. It was the Humber; no one ever fishes it because it’s two miles wide. But this time it had burst its banks, and they were just there, in the ditches, in their thousands. We had to hire a truck to get them to market. This ban is wrong, because no one has any idea, at all, how many eels are really out there.” He has a point. But to grasp the problem, we need to begin at the other end of the eel’s life cycle, not with the muscular monsters Hackforth and Britain’s remaining eel fishermen haul up in their fyke nets. And whatever the ancients imagined about the eel’s origins, the reality is just as strange. On a crisp autumn morning by a sluice gate on the King’s Sedgemoor Drain in the Somerset Levels, Andy Don, Environment Agency technical officer and all-round eel expert, recounts one of the natural world’s most extraordinary stories.

Baby eels are hatched from eggs in the upper levels of the warm, unfathomably deep Sargasso Sea, halfway between Bermuda and the West Indies. “They’re minute at that stage, willow leaf—shaped, called leptocephali -- ‘small heads’,” says Don. Over the next couple of years, they drift across to Europe on the Gulf Stream. When they arrive at the Continental Shelf, generally in early spring, they change shape: they’re now cylindrical, not flat.

At this stage, now known as glass eels, the tide washes them into UK river mouths. Some stay in the estuaries. Others work their way upstream, “burrowing into the edges and margins, penetrating way inland”. These are elvers, perhaps still only 7cm or 8cm long. As they go, they gain colour. If the ground is damp, they’ll travel overland.

And when they’ve reached somewhere they’re happy, they stay, as yellow eels, feeding and growing and swelling and darkening, for perhaps seven years if they decide to become a male, and 12 if they’re female. Some live undisturbed in forgotten pools for 25, 30, even 40 years.

And then, says Don, “one dark night, usually in September or October, usually after rain and when the moon’s overcast, they get the call. No one knows why. They turn a kind of mottled green—black on top, silver underneath. They head downstream on the flood, and swim 5,000km back to the Sargasso Sea. Then they spawn, and die.” (Eels being eels, no one has actually seen this last bit happen. It’s scientific conjecture, a theory first elaborated in 1922 by a dedicated Dane, Johannes Schmidt, who devoted 15 years of his life to hunting tiny, almost transparent larvae 7mm long in the mid—Atlantic. And although no one has ever found an adult eel, let alone an egg, in the Sargasso Sea, no one has yet disproved his theory either.) No one knows, either, exactly why glass eel numbers have plummeted. It could, says Don, be to do with slight shifts in the Gulf Stream’s direction: the baby eels may be getting swept past the British isles. Or it could be changes in its temperature. The eels’ wetland habitat has also shrunk down the years, and a parasite is playing havoc with their swim bladders, affecting their ability to move up and down through the ocean’s layers. Perhaps a buildup of pesticides in their bodies means the adult eels are not as fit as they were when they spawn.

What is certain, says Adam Piper, who is doing an agency-funded PhD on eel behaviour, is that a growing number of increasingly impermeable man-made structures on Britain’s rivers are making their journeys harder. “Look at what they face now,” Piper says: “Weirs, locks, sluices, pumping stations. All built of concrete and steel, not leaky wood. Anything hydraulic is a disaster; turbines just chop them up.” Piper is working on how eels cope with different types of barrier, and why they choose one route over another. “They seem to be seeking out a path,” he says, “not just going with the flow.” There is also, of course, the fishing. Not that Britain is a big eel fishery, stresses Heidi Stone, the agency’s senior technical adviser: it hauls in a negligible 2% of Europe’s total eel catch. Barely 1,000 men here still fish for silver eel, with bag-shaped “fyke” nets or old—fashioned traps, and for glass eel with special dip nets -- though glass eel fishing, centred on the rivers Severn, Wye and Parrett in the south-west, can be an exceedingly lucrative business.

The Parrett in particular, says Stone, is “elver central”, accounting for almost all the glass eels harvested in the UK. “Round here,” explains Don, “elvers were so abundant they used to use them as fertiliser. Then someone figured out you could feed glass eels on: grow them.” Eel farms took off in Holland, and Asia, an even more massive market. In the 90s, it exploded: “These little fish, a couple of inches long, were worth a fortune.” At the peak of the boom, a kilo of glass eels would fetch GBP575; this season’s price was more like GBP220, still plenty in a part of the country not noted for its wealth.

Under the European eel recovery plan, much of the elver catch now goes for restocking. But on busy nights, the Somerset glass eel fishery can, warns Don, turn “quite nasty. In one spot someone might be earning two grand in a night, and in another, nothing . . . It can get quite heavy.” Heavy or not, Britain’s share of Europe’s eel catch can hardly be endangering the species. Immeasurably more damage, say the fishermen, is done by the commercial trawlers in the Bay of Biscay, and the villages in Spain and France whose economies depend almost entirely on elver fishing. France especially, it is rumoured, is flouting its restocking obligations and flogging as much as 15 tonnes -- each tonne representing 3-4m baby eels -- to China.

At a tense September meeting with Environment Agency officials in Lincoln, Anglia’s eel men are far from happy. “Look at us,” says Gary Lee. “We’re not having any impact on the species at all. There’s been no real drop—off in our silver eel catch. All these samples and studies, none of them show anything.” In any case, adds Terry Smith, the problem will “solve itself. Twenty years ago, there were 100 eel men in north Lincolnshire; now there are three, and not one of us under 50. Another few years, we’ll all be gone.” In the Brown and Forrest smokery in Hambridge, Somerset, owner Jesse Pattison isn’t best pleased either. He smokes around eight tonnes of British eel a year, selling by mail order and to restaurants around the country. There are, he says, smokeries in Holland that ship many, many times more each week.

“We’ve always worked sustainably,” he says, an array of glistening eels smoking gently behind him. “We work closely with our river keepers and individual fishermen. We don’t import. We’ve always done things right, and now we get hit with this. The problem is the headline: Eels are heading for extinction. That’s what the conservationists see. But on a European scale, we’re insignificant.” Longer term, Pattisson is cheered by news that second—generation cultivated eels have just been produced in Japan, using artificially inseminated, collected eggs. Until now, no one had ever bred an eel in captivity.

Patiently, Stone explains that the ban is a one-off, a holding measure in response to EU demands while new UK legislation comes in, hopefully by the end of the year. “We could have banned eel fishing outright,” she says. “Norway has, Ireland has. I don’t consider that a responsible, well-regulated and sustainable fishery is part of the problem. But we do have to demonstrate that’s what the British fishery is.” Under the new management plans, a more flexible system of authorisations will replace unwieldy licences, with eel men providing accurate figures on their catches. Pumping stations and other water intakes will have to fit screens, so eels don’t get sucked in. On weirs, locks and sluices, eel passes -- fibreglass gutters, each fitted with a forest of short plastic bristles, and with a trickle of water running down them -- are being hastily installed.

“They’re low-cost and amazingly effective,” says Andy Don, whose baby the scheme is. “If you put them in, the eels will come.” Two days after his very first eel pass opened on King’s Sedgemoor Drain, he watched open-mouthed as CCTV footage from the previous night showed 11,000 elvers wriggling their way up through the bristles and onwards, upstream. “This sluice was an impassable barrier,” he says. “We spend a few hundred quid and” -- he gestures happily -- “now it isn’t.” I meet Clifton-Dey, who did his master’s degree on eel migration, very early one morning at Molesey Lock. The Environment Agency is doing a spot of electro-fishing on the Thames: lowering an electrode into the water from a small boat, momentarily stunning every fish within three metres. Today it’s eels we’re after. Data collected from the Thames over the past 15 years suggest “there might be the beginning of a decline in the adult freshwater population”, Clifton-Dey says. “Something to keep an eye on.” In the boat, Darryl’s colleague Dan Horsley plucks an eel from the tank and wraps it swiftly in cloth. It stops thrashing, but he still has to hold it down, using both hands. Its vital statistics recorded, Darryl lowers it gently into the river. It shrugs once, and vanishes. “Slippery as an eel” is absolutely right. Whether that expression will mean something to our grandchildren, no one can yet say.