Let's get real about eel: The slippery fish will soon be coming back on to the menu

Eels and Easter arrive together. The eels are needle-sized babies, called elvers or glass eels because they're totally transparent, reaching British shores at the end of an exhausting 4,000-mile mara- thon swim from the Sargasso Sea where they spawn.

For generations, the arrival of migratory so-called European eels used to be anxiously awaited at this time of year by fishermen on the Severn and Wye tidal rivers. They collected them in nets at night then fried them up with bacon and scrambled eggs to make a delicious dish looking like a plate of marine spaghetti. The tiny glass eels gave it a delicate crunch. Sometimes they were even mixed with herbs and transformed into a "cake".

Those fishy feasts, though, are largely a thing of the past. The eel is in trouble. The Marine Conservation Society places eel on its Red List of Fish to Avoid, classing it as critically endangered. Conservation groups want a total ban on eel's exploitation until stocks recover and have successfully persuaded chefs from Gordon Ramsay to Jamie Oliver to drop adult eel from their menus.

Even London's Japanese restaurants, for whom oil-rich meaty eel is one of the most prized ingredients, are shunning it. Silla Bjerrum, who runs eight restaurants in the Feng Sushi chain, hasn't served eel for 18 months.

Thanks to its unique life cycle, however, the eel's predicament is different from other fish. Its collapse is not just the result of overfishing but also of mismanagement of the tidal rivers, according to Richard Cook, who has lived and fished on the Severn all his life and runs a smokery. "Although the number of elvers is down, there are still millions during the season. We're not talking pandas, where just a few remain. The elvers' biggest problem is that they can't get out of the tidal rivers into the freshwater streams and rivers where they feed and grow into adults," he says.

Richard takes me to a spot on the Severn near his family home. "Places like Walmore Common, on the river's flood plain, used to be under water most of the year. It was the ideal nursery for glass eels, which hid in wet ditches as they slowly migrated upriver. Now it's been drained for farming."

He shows me a sluice gate. "These are the other problem – the tidal rivers are now sealed, so the eels can't get out. Pumps and hydro systems are disasters as the eels get caught up in them and mashed."

Richard is part of a Europe-wide coalition of conservationists, scientists, Environment Agency officers, National Rivers Trust members and industry leaders called The Sustainable Eel Group. The group is devising a recovery plan that includes finding ways to unblock the eel's migratory routes.

Doing that will take years. In the meantime, the Group has another solution: to pay licensed fishermen to catch elvers from tidal rivers so they can be moved to waters where they can flourish. Some 40 per cent are returned to inland rivers to boost stocks, 60 per cent go to fish farms in Europe.

"Doing nothing isn't an option," says Richard. "It's not like cod, where the best solution is to leave them alone. If we leave eels to fend for themselves in the big tidal rivers, 99 per cent of them will die."

Richard is even enlisting local schools and chefs in the recovery effort. Over the next few weeks he will take tanks of glass eels into 50 primary schools whose pupils will feed them for around 10 weeks until the fish have doubled in size. The children will then release them into local inland rivers – while sampling Richard's smoked eel. Some tanks in the Eels in Schools scheme are sponsored by chefs including Martin Wishart, Mitch Tonks and Brian Turner.

Some conservationists complain there's little evidence that such measures are helping to boost stocks so still advise consumers to shun all eel, farmed or wild. But Richard believes the measures are the best way to ensure the eel's future. "In the wild, two kilos of elvers will grow to nine kilos in adult weight. In a farm, they'll become 1,000 kilos," he says. "Farming eel is a no-brainer." The Sustainable Eel Group is now labelling eel that it deems sustainably farmed with a logo that will appear on fish sold in shops and on restaurant menus.

The first packs of "sustainable" eel went on sale this week in Richard's smokery. The fish was also served as a starter, with beetroot and horseradish, at an Action against Hunger charity dinner cooked by some of Britain's food critics, including The Independent's Tracey MacLeod.

"Our message is that chefs and consumers should never buy wild adult eel," says Richard. "But if they buy eel carrying the Sustainable Eel logo they can serve and eat it with a clear conscience. If there's no demand, people will stop worrying about the eel's future."

As night falls, we join rows of fishermen on the Severn, each on their particular "tump" (fishing spot), often passed down from father to son. Their headtorches make them look like nocturnal Ninja turtles, and they hold large hand nets in the fast-moving waters.

There's a full moon, mists rise off the river like clouds, and the only sounds puncturing the silence are mobile phone conversations checking tides and comparing hauls. From time to time they brush a clutch of wriggling elvers into plastic buckets.

At 2am we leave them to it and head for the weighing-in station inside a Gloucester warehouse where a handful of fishermen place trays of their precious catch on the scales and exchange them for wads of £20 notes.

It's an insight into a hidden world that few know exists. But will it save the eel, and will chefs and their customers be convinced? "It's a complex issue," says chef Silla Bjerrum. "If I can be sure my eels have been fished from a restocking programme and farmed sustainably, I'd consider buying it."

Whatever the way ahead, few will disagree that this mysterious fish is too precious – and tasty – to lose.

severnandwye.co.uk

sustainableeelgroup.com

Ways with eel

Jellied eel

Relished by inhabitants of the East End of London since the 18th century and traditionally served with vinegar in Eel Pie & Mash Houses. It's made by simmering eels with chopped onion and bay leaves. As the mixture cool and sets it forms a jelly.

Unagi kabayaki

The Japanese way. Eel (unagi) is dipped in a sweet soy sauce then grilled. Served on top of steamed rice.

Eel pie

Traditionally served with mash and "liquor" in the East End. The TV chef James Martin's version includes leeks, whelks and clams.

Matelote

A delicious French dish in which eel is combined with carp, onion, red wine and herbs and gently stewed.

Aalsoep (Dutch eel soup)

One of Holland's best known national dishes, this simple soup consists of fresh eel, parsley and capers.