Eel Breeding

Eels are found in many parts of the world, from Europe and the USA to the Far East and also Australasia, though they are absent from the west coast of North America and from South America. Species include the European eel Anguilla anguilla, the very closely related American eel Anguilla rostrata and the Japanese Anguilla japonica. The European and American eels migrate from freshwater to the mysterious depths of the Sargasso Sea to breed, and the Japanese to just north of the Pacific Mariana trench.

The Japanese, like the Danish scientists in the Atlantic before them, spent years (1967-1991) sampling with a plankton trawl trying to discover the breeding grounds of Japanese eel. They found that these eels, which start the breeding run from freshwater around the night of the new moon, also mate on a night near the new moon. They appear to breed near ‘seamounts’ where they may be able to detect special odours, turbulences, local magnetic fields or some other feature of the seamounts that helps them to congregate to mate near the ridge. They may also choose an area of a particular salinity, a so-called ‘salinity front’. The females release eggs into the water to mix with the sperm of the males and it is likely that they mate, as they migrate, en masse rather than as pairs

In Europe the Dutch, the Danish, the French and the Italians have long dominated the eel fishing industry, but the Japanese obsession with eels has lasted at least a thousand years. They eat far more eels than anyone else, estimated now at 70% of the eels eaten globally; they are literally eating their way through the world’s eel populations. The growth of the European eel market in the late nineteenth and early twentieth century is comparatively insignificant compared with that of the Japanese, who regard  the eel, unagi, as a powerful ‘stamina food’. Whereas in Europe in the Middle Ages eels were seen as appropriate food during Lent when carnal passions needed to be cooled, in Japan their strength and phallic appearance have given them the opposite kind of reputation, known as biyaku, .leading to Japanese wives feeding unagi to their husbands to inspire passion, and a belief that eel imparts strength and vitality, which has led to it being an important ingredient in sushi and to the Japanese market putting a huge strain on wild populations of eels worldwide, comparable maybe with their effect on whale populations. To supply the demand for farmed eels, Japan began importing elvers from Taiwan in the 1950s and from Europe in the 1960s. The elver depot at Epney on Severnside, founded by a German before World War 1, and UK Glass Eels, founded in Gloucester docks in the 1970s, were quick to supply this market, along with various Severnside fish merchants such as Horace Cooke of Minsterworth. In the elver season their trucks parked at selected laybys near the banks of the Severn and local elver fishermen swapped elvers for increasingly large wads of cash as the market grew. At the time it seemed to me strange that we should allow the export of elvers to the Far East when better alternatives existed, such as cultivating eels ourselves, or allowing them to continue upstream to populate the ecosystems in which they belonged. I can find little evidence of any official concern about this unregulated fishery during the twentieth century, even by the Inland Revenue. The eel fisheries in England were not thought significant enough for fisheries scientists to concern themselves with working out sustainable catch levels, and as a nation our understanding of the need to look after the biosphere as a whole was at a primitive level.We appeared to believe that a few nature reserves were all that was required. It was only when concern was expressed at a European level at the sudden decline in eel numbers in the 1980s that the UK was forced to take the problem seriously, and it is doubtful if we would have passed the Eel Regulations in 2009 were it not for the European Union requiring us to do so. As it is we still have the Sustainable Eel Group, which, like the Sustainable Eel Group Foundation in the Netherlands, managed to persuade the European Commission in 1922 to ignore their own scientists’ advice that a total ban on eel fishing in Europe was necessary. The word sustainable does not guarantee anything, and I am reminded of the way lorries disposing of toxic waste in the countryside in the 1960s and 1970s usually bore a company name that included the word ‘environmental’.

Eel is eaten in Japan at midsummer, on the Day of the Ox, in order to give strength and vitality for the coming year, and widely eaten at other times of the year as well as being used as an aphrodisiac. Tokyo has some 950 restaurants that specialize in eels cooked in the traditional way.  It is also seen as a cooling summer dish, when some restaurants will serve little else. The growing international popularity of sushi has also contributed to worldwide eel population crashes, because Japan trades in elvers from around the world wherever the trade is permitted, and is also willing to pay prices for elvers that encourage smuggling. The illegal global trade in European eels is worth up to £2.5 billion each year. In February 2022, Gilbert Khoo, a Malaysian-born seafood trader, was convicted of moving £53 million worth of eels through the UK. Between 2015 and 2017, Khoo smuggled 6.5 tons of live elvers to Hong Kong for sale to eel farms. That is nineteen and a half million individual endangered eels. That is also – you have no doubt seen huge wildebeest migrations on the telly – equivalent to thirteen times the total world population of wildebeest, smuggled by one man.

Japan is an important centre for eel farming, and 90% of the eel sold in the US is also farmed. When fish farming first developed it was seen as a benign alternative to exploiting wild stocks, but eel farming has had extreme effects on wild eel stocks because it has not been possible to breed eels in captivity. Eel farming has been entirely dependent on buying wild elvers and shipping them to countries like Japan and increasingly to China, which is starting to dominate the market. Eel farming is now increasingly being criticised as another form of industrial farming, where unnatural conditions and disease risk leading to antibiotic misuse are among the criticisms made in a world increasingly questioning our insistence on eating animals. Additionally it is threatening wild species already in decline as a result of factors almost certainly linked to industrial farming, such as pesticide pollution.

In the 1970s sea eagles in Norway were found to be dying in the winter when lack of food caused them to use up their fat reserves, releasing pesticides stored in the fat. Eels undertaking the long journey to the mating grounds may well be exposed to such a risk too. This is the sort of pesticide effect that might threaten the species but be very hard to demonstrate because the eels would die out in the Atlantic before they reached the breeding grounds. The Norwegians solved the problem by putting carcases out on frozen lakes to feed the eagles and stop the chemicals being released from their fat reserves, but if something similar is happening to eels we are unlikely to discover it before it is too late. Although the precautionary principle is actually enshrined in European law and should prevent the use of biocides unless we can prove they are harmless, the ‘business as usual’ principle appears to be more widely observed, along with the ‘if we didn’t do it someone else would’ principle.

The demand for eels, and current shortages, results in very high prices being paid for elvers from Europe and America shipped to places like Japan, which in 2021 transferred about 20 tonnes of elvers (60 million individuals) into its eel farms. But so much of the trade is in smuggled or illegally fished eels that such figures are probably a wild underestimate and 60%b of the eel catch in Japanese waters in 1922 was traded illegally. South Korea, Japan and Taiwan have refused to drop their upper limit on catches of juvenile eels, and China, with the biggest single annual quota of 36 tonnes, resists all international efforts to limit catches. The import of elvers into East Asia from Europe has declined since the European eel regulations were introduced, despite the lucrative trade in smuggled elvers, but the import of elvers from other parts of the world has increased and can be expected to increase further especially with the involvement of the Chinese in the international eel market.

Although there is a severe shortage, Japan, Korea and Taiwan continue to resist attempts to limit catches of eels and elvers, although elver catches have declined to about one fiftieth of the amount caught in the 1960s. It is hard not to compare the Japanese attitude here with their intransigence in the face of international efforts to protect the great whales.

The Japanese have been leaders in the attempt to breed eels, using very complex and intrusive techniques that have not so far succeeded. Eels do not develop reproductive organs during their freshwater phase, although the females are believed to be considerably larger than the males when they reach the age at which they migrate, and there has been much speculation about whether their sex, actual or incipient, is not fixed at birth and may depend on the conditions prevailing in the habitat. It is believed that as eels migrate to breed their stomachs are reabsorbed, and their gonads develop as they travel between 3,000 and 6000 miles to their breeding grounds. The journey takes them past the Azores, a long slow route that conserves their energy and reduces the risk of mortality, sometimes travelling at depth of more than 1000 metres. It has been difficult to replicate the conditions that stimulate breeding, at least partly because we do not know exactly which conditions are required, and finding out how to farm the planktonic larval stage, the leptocephali, and what conditions are required for them to transform into elvers, are as yet unsolved problems. German scientists have manged to artificially reproduce European eels but in 2017 the team at the Thünen Institute of Fisheries Ecology, near Hamburg, said that they had so far been unable to extend the survival of the larval stage, the leptocephali, beyond 23 days and believed that artificial breeding remained in the distant future.

 Until Japanese and other Far Eastern countries perfect the breeding of eels in captivity, the huge demand for elvers for their fish farms is likely to threaten eel stocks worldwide, because increasing scarcity fuels an increasing price, a mechanism that remorselessly fuels extinction, and eel species not yet exploited in other parts of the world are likely to come under pressure. The American eel, like the European eel, is now under threat for this reason.

Eels in the eastern United States, as in Europe, are important actors in their ecosystems. They are known, for example, to be used by freshwater mussels to transport their larvae, which attach to the gills of eels moving upstream through the catchment. This mechanism counteracts the effect of the current in rending to wash mussel larvae downstream, and enables the mussels to maintain their population high in the river catchment where their filter-feeding has beneficial effects on the whole riverine ecosystem. This might serve as another example of the complexities of interactions between species in ecosystems, which are often ignored in our squalid calculations of how much of a pesticide we can use without, for example, beekeepers noticing that their bees are dying.

The international demand and high price of elvers has led to a gold rush in places like Maine in the United States.  I say gold rush advisedly – a 5-gallon bucket of elvers is worth $50,000 there, a higher price per kilo than that of gold. American elvers were sold for as little as $24 a pound until recently, when the decline of the European and Japanese eel populations by figures estimated at maybe 90%, followed by the European ban on exports, pushed up the price of elvers to $2000 a pound, or around $5000 per kilo, sixteen times as much as the peak prices along the Severn before the ban took effect.

Elver fishing is only legal in Maine and South Carolina. A catch of 21,611lbs of elvers was recorded in 2012, but as there is no limit on catches and many of the transactions were off the books along the banks of remote creeks, there is really no reliable figure for just how many were caught, and the legally caught elvers were mixed with elvers poached by unlicensed fishermen before they were shipped out to Asia. Luckily the US Fish and Wildlife agency launched Operation Broken Glass, a sting operation to counter elver poaching and trafficking.  Twenty eel poachers were caught, ranging from small fishermen to powerful business figures. Elver prices rose from $185 per pound in 2010 to $1900 in 2012 because of the ‘sushi crisis’ sparked by the European ban on elver exports. \So much cash was changing hands on the banks of remote creeks that the dealers had to carry side-arms for protection. One of these dealers admitted trafficking elvers worth $500,000. As a result regulations have been introduced under which each fisherman now has a personalised catch limit recorded on a swipe card  and elver sales have to be made to regularised buyers with bricks–and-mortar operations as opposed to the previous pick-up trucks on country roads. The smuggling is likely to continue if the demand continues, of course, and as long as the mechanism by which the prices continue to rise as a result of the scarcity, eel populations must continue to be vulnerable to criminal exploitation

So the Japanese eel and the American eel are both highly threatened. It is possible that the European eel, because of coordinated European action, may be in a slightly improved position, although if Japanese and Korean and Chinese buyers are prepared to raise their prices until eels are traded to extinction no eels are safe. Unless the Japanese and the Chinese in particular develop a more sophisticated attitude to the exploitation of wild creatures, the future of eels may depend on developing the techniques needed to breed them in captivity. Fish farming was once hailed as a way of making the exploitation of wild fish stocks unnecessary, but it is generally an inhumane way to treat living creatures; in the case of salmon farming, the fish farms sited in the lochs frequented by wild salmon are suspected of spreading disease and pests to the wild salmon so as to actively threaten their survival. My own personal conclusion, that we should stop eating wild animals, may seem a little questionable, coming from someone who once made his living as an eel fisherman and poached both deer and salmon in his youth. I would argue that my background makes my views more compelling, but I guess I have no alternative but to let you be the judge of that.

(This is an edited extract from a book I am working on called The Eel Trap, with which I hope to snare a publisher some time soon. If you are a publisher or best mates with one, feel free to get in touch. Oh, and while I’m on, Happy Christmas to all my readers!)