Biodiversity Britain Food Geographical Pollution Sustainability

The European eel – a critically endangered species on the menu of top European restaurants

Alan Thornett (pictured with a trophy eel in 1949) writes:

The most disastrous consequence, of today’s environmental crisis, is the catastrophic collapse of global biodiversity. This is now recognised as the greatest extinction event our planet has faced since the demise of the dinosaurs 65 million years ago. We ignore it at our peril, since we cannot survive without the millions of other species that live alongside us.

According to the Natural History Museum the UK is one of the most biodiversity-depleted countries in Europe.

Although awareness of this is greater today than ever before – thanks to the work of the global ecological movement, of dedicated environmental campaigners such as David Attenborough and Chris Packham, and indeed of the UN – the gap between awareness of the problem and doing something about it, remains frighteningly high.

The European eel

A case in point is the plight of the European eel (Anguilla anguilla) – a mysterious nocturnal ‘catadromous’ fish that is born in the open ocean but lives and grows in fresh-water rivers and estuaries. After been abundant for millennia, its numbers have crashed by 95 per over the last 40 years, and is now on both the Red List of critically endangered species and is the subject of a European Commission trade ban.

Despite this, eels are not only still on the list for human consumption, but eel dishes are being offered in restaurants across Europe as a top gastronomic experience.

This deplorable practice was (fortunately) exposed recently by Guardian journalist Ashifa Kassam in an article in The Observer of March 12. He reports that an ‘eel option’ was recently on the menu of a banquet staged for Robert De Niro in return for his assistance in promoting the 20th anniversary of Madrid Fusion ­ a global culinary extravaganza held on March 28-30 this year in Madrid.

Fortunately – for both the eel and for the biodiversity of the planet – this wanton piece environmental destruction came to the attention of senior environmental scientist at Spain’s National Research Council, Miguel Clavero Pineda, who promptly called it out. It was, he says, “like there is no awareness that this is a species on the brink of extinction”. No restaurant, he said, “would ever think of including Iberian lynx, for example, on its menu. But we’re eating eels!” He is absolutely right.

Not that it was an isolated incident, however. At Dutch fairs, Kassam says: “smoked eel remains a popular treat, while in Denmark it is paired with scrambled egg. In Italy some usher in Christmas with a meal of fried eel while in Spain, baby eels are served sautéed in olive oil, garlic and chilli pepper – and it sells for more than £880 a kilo.”

In the East End of London eels were a traditional dish in working class neighborhoods for centuries. According to the Pie ‘N’ Mash Guide ­ jellied eels were sold at Pie ‘N’ Mash shops in London – there were about 150 such shops in the East End of London in the 1930s. This was down to 20 by 2020 and a few still exist today. (Several supermarkets are still selling pots of jellied eels. Some of these may be farmed, but this is also unacceptable because it perpetuates the human consumption of an endangered species.)

There is also a thriving black market in eels. An estimated 100 tonnes of baby eels are smuggled out of the Europe each year – often stuffed into suitcases and lugged through airports – in order to circumvent the trade ban.

Remarkable life cycle

The European eel has an extraordinary life cycle, that includes one of the world’s greatest marine migrations ­ which increases its vulnerability.

They are hatched in the open ocean – in the Sargasso Sea off Bermuda – into tiny transparent leaf shaped larvae that then drift across the Atlantic on the Gulf Stream. Two years and 4,000 miles later they arrive in Europe where they metamorphose first into tiny ‘glass eels’, and then into ‘elvers’(or young eels) to continue their journey into the river systems. There they change, first into ‘yellow eels’, and live as such for up to 30 years, and then into ‘silver eels’ that are able to expand their eyes and re-adapt to salt water before setting off on a sixth-month swim back to the Sargasso – against the Gulf Stream this time – to spawn once and then die.


The biggest single factor in the collapse of European eel numbers has been the ever-increasing levels of pollution of the river systems across Europe – and the UK has been the worst offender. The lower reaches of the Thames – from London to the English Channel – have been the hardest hit and has been rendered biologically dead – i.e. it no longer contained enough oxygen to sustain life ­ twice in the past 200 years.

The first was the ‘great stink” of 1858 when the dumping of the whole of London’s sewage into the Thames led to a stench that rendered the city unliveable. This led to the construction of the London sewer system which initially resolved the problem. By the turn of the century, however, it began to recur.

A study of the Thames, in 1950, from Kew to Gravesend found no signs of life, and in 1957 the Natural History Museum declared that the lower Thames was (once again) biologically dead. Efforts were made in the 1960s to reverse this. Waste treatment plants were improved and industrial waste was reduced and some progress was made. Oxygen was even pumped into the river from so-called bubble boats.

This was cut short, however, in 1989, however, when Margaret Thatcher privatised the water industry, which took the problem to a new and more generalised level.

A comprehensive study of the eel population, over the length of the Thames, was carried out in 2010 by the Zoological Society of London and reported in the Guardian. It found that eel numbers had crashed by 98 per cent.


Another major contributor to the demise of fish like the eel, that migrate into river systems, is the number of human constructed blockages they have to face – from Locks to hydro power generators. A study by the University of Southampton, in 2018, found that there are a staggering 1.2 million such obstructions blocking European rivers, which amounts to one every kilometre.

Last year a remarkable study by the Thames Catchment Community Eels Project – a citizens science project with a government grant – found that rivers in England and Wales contain more such obstructions than anywhere else in the world.

River obstacles it points out: “can severely impact the localised movement of fish species within rivers and, in the case of some salmonids and the European eel, the migration between rivers and the sea. These barriers to movement can have severe consequences for populations of fish by limiting their ability to move between feeding and spawning grounds. Because of this, river obstacles are considered one of the major threats to the populations of some fish species in the UK.”

It listed over 30,000 weirs, locks, power plants, waterfalls, sluices, dams, culverts, fords and flap gates in England and Wales that are causing the problem – and they provide a River Obstacles App (yes an APP) that will tell you about, or take you to, any one of them.

Although fish bypasses have been installed at some installations they are as yet only partially effective – even for eels that can leave the water in some places in order to bypass such obstructions.

My own ‘contribution’

The reason Kassam’s expose’ caught my attention was because eels – i.e. catching them – played a big part in my childhood. I grew up in Abingdon, in rural Oxfordshire, which is where the river Ock meets the Thames – of which it is a small 15-mile long tributary.

What marks the Ock out is that it is a chalk stream – which is amongst the rarest of aquatic habitats. In fact, there are only 210 chalk streams in the world, of which 160 are in Southern England. It emanates  from the base of White Horse Hill, a chalk hill in the Vale of White Horse above Uffington. Like other chalk streams its water was exceptionally pure having filtered through chalk for hundreds of years.

In the 1940s it teamed with fish such as roach, pike, perch, tench, bream, dace and also eels – and fishing was one of my main preoccupations, particularly eels. It also supported large numbers the UK’s now almost extinct, native white-clawed crayfish – which flourished in such streams. Kingfishers, herons, and water voles were also plentiful. There were reputedly otters, but I never saw one. The Abingdon Museum displayed a taxidermic example caught in the Ock.

I was – surprisingly – fully aware at that time of the life cycle of the eel, since it had been discovered by zoologists at the end of the 19th century and this was well known. I was aware, in other words, that before an eel could encounter me in Abingdon, it would crossed the Atlantic, found the Thames estuary, swam for a 160 miles up-stream to Abingdon, and located the confluence with the Ock. Not that it cut any ice with me at the time. This is, therefore, my mea culpa.

Today the Ock is as polluted as the rest of UK rivers, mostly due to agricultural run-off. An important study of the Ock Catchment was carried out by the Freshwater Habitat Trust in 2016 which was also based on citizen science. Its citizen researchers took 579 water samples at 570 sites – just over one per square kilometre ­ in a one-month period from 19th March to 25th April 2016.

The study concluded – unsurprisingly – that the Ock contained high levels of nutrient pollution: It put it this way: “Clean water in the Ock Catchment is concentrated in ponds and lakes, and like most areas of lowland Britain, the majority of streams and all the rivers, suffer serious nutrient pollution. This is not surprising because the catchment drains water from large areas of land with multiple sources of pollution from urban and agricultural areas”.


The grim conclusion from all this is that the biodiversity crisis that stands behind all this remains entirely unresolved.

The UN Biodiversity Conference (COP15) in Montreal, in December last year, agreed for the first time to halt biodiversity loss over 30 per cent of the land and 30 per cent of the oceans by 2030.

This is welcome but desperately inadequate. The COP, itself, accepted that: “a million species already face extinction, many within decades, and that unless action is taken to reverse biodiversity loss there will be a further acceleration in the global rate of species extinction, which is already ten to hundreds of times higher than the background rate over the past 10 million years.”

Meanwhile, in the UK, the dumping of raw sewage into the rivers and onto the beaches by the privatised water companies has reached medieval proportions. According to the BBC raw sewage is being routinely pumped into our rivers and onto the beaches an unbelievable 825 times a day. Repeat 825 times a day.

Fortunately, this beyond scandalous situation is now rising rapidly up the political agenda. We have to demand that the water industry is brought back into public ownership and restructured and reorganised as a matter of urgency.

But we need more. We need a fundamentally different relationship ourselves and the natural world – both collectively and personally. We have to resolve climate change. We have to live as a part of nature and not at its expense. We must defend vulnerable habitats in every area of our activity. We need a major change in farming methods and to move faster towards a plant-based diet. We have to stop trashing the natural world for our own ‘enjoyment’. Blood sports should be banned, but not only hare coursing, fox hunting, and bear baiting but recreational fishing as well.

Alan Thornett May 31st 2023.


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