The first time I tried to grip a freshwater eel was during an interview with a North Carolina eel dealer, who reached into a concrete-lined pool in his warehouse and tossed one of his captives to the floor in a quick movement. “Pick it up,” he said, with a slightly nasty smile and a challenge in his voice. He nodded his head toward the eel, an adult a yard long and as thick as a baseball bat. It was already making good time squirming across the concrete floor, looking unnervingly like a big snake. Still, I knew that eels are fish and that they don’t have much of a bite, and the task sounded easy enough, so I stooped to scoop the eel off the floor, putting both hands around its body and squeezing. It was like trying to hold a handful of water. In a flash, it slid through my fingers back to the floor, leaving a smear of slime drying on my hands.
[ad: 51 1094]Then the dealer showed me the trick. It’s no secret; it was aptly described in an anonymously authored book called Athletic Sports for Boys: A Repository of Graceful Recreations for Youth, published in 1866 in New York. The book included eel fishing as one of those graceful recreations for American boys, and taught them how to handle their catch: “Place the second finger on one side of him, and the first and third on the other, about an inch and a half from his neck. Then by pressing the fingers together he cannot move.” It works.
The idea of an afternoon spent fishing for and handling eels has long since fallen out of favor in the United States. Likewise, eels themselves have disappeared from North American cuisine, where for a long time they held a high place. A handful of eel dealers still buy eels on the U.S. east coast for sale to Europe and Asia, but a significant North American market no longer exists.
Even though people around the world have been eating freshwater eels, and researchers (beginning with Aristotle) have been studying them, for thousands of years, much about the animals remains unknown. Spurred by global population declines, however, scientists are beginning to unlock some of the freshwater eels’ millennial mysteries. And they are closing in on the long-standing goal of breeding eels and raising them to adulthood in captivity on a commercial scale, in hopes of freeing the aquaculture industry from the need to gather young eels from the wild.
More than 700 species of true eels, in the order Anguilliformes, have been identified around the world. Fourteen families of exclusively marine eels include morays and congers; one family of freshwater eels, the Anguillidae, consists of sixteen species, all in the genus Anguilla. Among them, the American eel (A. rostrata), European eel (A. anguilla), Japanese eel (A. japonica), and Australian or shortfin eel (A. australis) have each sustained humans for thousands of years. Paleolithic cave dwellers in what are now France and Spain left European eel bones in their trash middens. Australian aborigines and Native Americans consumed their local species, as did the Greeks. “Fear death,” wrote the Greek comic poet Philetaerus in the fourth century B.C., “for when you’re dead, you cannot then eat eels.”
Members of the Anguillidae are catadromous: they are born and die in salt water, but mainly pass their lives in fresh, a life cycle opposite that of salmon and other anadromous fishes. Every ordinary-looking eel resting in the mud of a North American or European lake, pond, river, or creek has made an astonishing journey from its birthplace in the depths of the Atlantic Ocean’s Sargasso Sea—an approximately two-million-square-mile zone between Bermuda and the Azores. The Sargasso is bounded by strong clockwise currents, which carry the thin, leaf-shaped eel larvae, called “leptocephali,” hundreds or thousands of miles northwest to North America and then northeast to Europe. The two species, American and European, are distinguished by the number of their vertebrae, as well as genetically. American eel larvae also grow faster; they’re ready to hop off the ocean current and head for shore in a year or less, whereas the European larvae continue to go and grow with the flow, possibly for as long as three years.
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As they near land, having reached about two and a half inches in length, the leptocephali metamorphose into “glass eels,” their bodies adapting to freshwater and rounding out in cross section (see diagram). At that stage hundreds of millions of juvenile eels are netted—legally and illegally—out of estuaries each year, mostly to supply the Asian aquaculture industry. Stronger swimmers now, many glass eels that escape the nets enter a river and swim upstream in search of a freshwater body to call home. (Some stay behind in coastal waters.) As the glass eels grow they develop pigmentation, at which point they are called “elvers.” Once they exceed six inches in length and darken to their characteristic muddy yellow-brown-green color, they are called “yellow eels.” When they find a home they like—some females forge as far inland as South Dakota—they stay there for years, passing their days resting in the mud and their nights hunting.
When they are somewhere between five and twenty-five years old, having grown as long as five feet, yellow eels mature sexually and enter the “silver-eel” phase of their lives. Their backs darken and their bellies whiten for oceanic camouflage from predators above and below; their eyes enlarge and change pigmentation for improved vision deep in the ocean. They head back downriver, on a long return swim to the Sargasso. Their digestive systems atrophy, and they fast during the entire trip. They have no need to hunt; they have only to swim, arriving with just enough energy left to spawn before they die.
That description of an eel’s life cycle has been accepted since 1923, when a Danish researcher, Johannes Schmidt, published data from eighteen years of trawling for eel larvae in the Atlantic Ocean. He showed that larvae caught in the Sargasso Sea were so small that they must have hatched nearby. But though adult eels are frequently taken during their downriver journeys to the sea, none have ever been captured in the Atlantic, and it was not until 2008 that the first were found in any ocean. That’s when a crew of researchers from Japan netted three freshwater eels—two Japanese eels and a giant mottled eel (A. marmorata)—about eighty miles off a seamount in the western North Pacific. Dissection revealed the eels to be sexually mature males, and a few days later a different ship found recently hatched larvae nearby. Scientists had been zeroing in on the area as the Japanese eels’ spawning grounds, and here, at last, was proof.
The trawling expedition’s leader was Seinen Chow, a marine biologist with the National Research Institute of Fisheries Science in the city of Yokosuka. Dubious about the project’s chances of finding an eel, he’d initially declined to participate. “I thought it would be a waste of time,” he says. The team dutifully developed protocols for what to do if they did capture an eel, but they were thoroughly surprised when, on the tenth night of trawling, they actually netted one. “It was panic on board,” says Chow. “We forgot all our protocols for the moment.” The crew couldn’t do anything at first but stare at the eel.
In June 2009, the same team netted another eight Japanese eels, males and females, in three weeks of trawling. The eels are thought to swim deep below the surface, at some 600 yards, during the day and to rise quickly at sunset to 200 yards. Indeed, Chow’s team netted their eels at night.
Starting in 1974, scientists have made numerous attempts to track silver American and European eels on their way to the Sargasso—without much success. “Pop-up satellite tags” are the latest in tracking technology. Would-be eel trackers can attach one to an anesthetized eel with a wire pierced through the animal’s dorsal muscle. The eel is released, and after a certain pre-programmed time, or at a certain depth, the tag pops off. It then floats to the surface, where it transmits stored data about its journey with the eel to a satellite.
In October and November 2008, scientists from the Eeliad project, a consortium of European research groups, released forty satellite-tagged silver A. anguilla eels in Ireland’s Galway Bay, and forty more from the mouth of the Loire River in France. Eighty more are scheduled for release in autumn 2010. Additional eels are being let go with older-style data-storage tags implanted in their bodies. Eventually, the researchers hope, the tags will provide information about migratory behavior that will be useful not only in capturing elusive adults on the spawning grounds, but also in managing stocks, which are in trouble.
By July 2009, sixty-two tags had floated to the surface and transmitted data, the farthest from about 950 miles off the Irish coast, well short of the Sargasso Sea. Still, with funding secured through 2012, the Eeliad’s director, David Righton, a marine biologist with the United Kingdom’s Centre for Environment, Fisheries and Aquaculture Science in Lowestoft, England, is optimistic the project will succeed. “We didn’t expect to reach the Sargasso the first time,” he says.
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The Eeliad project is a component of the European Union’s response to a dramatic drop in eel populations—and Europe is not alone. Over the past decade eels have declined around the world. Nowhere have falling numbers caused more alarm than in Japan, which has the world’s largest per capita consumption, and where eels represent a $1 billion annual market. The Japanese consume some 200 million pounds of eel a year, most of it prepared as kabayaki—slices of eel that are butterflied, skewered, marinated in a soy-based sweet sauce, steamed, and grilled for a smoky flavor. Not nearly enough A. japonica is captured each year to feed the national appetite, so the Japanese depend on glass eels captured in Europe, or to a lesser extent in North America, and raised to eating size on farms in China or Japan. The EU is placing increasingly stringent regulations on that commerce, however, which lends urgency to research into captive eel reproduction. Recent breakthroughs have been major, but the work has not been easy or rapid.
Japanese researchers made a giant step forward in eel reproduction in 1973, when, building on earlier work, they induced fertility in males and females with hormonal injections and produced larvae from the fertilized eggs. The larvae lived for the five or six days it took them to consume their yolk sacs, and then died. Later researchers tried a variety of diets, from egg yolk to rotifers, but the larvae grew poorly, if at all, and did not live much past two weeks. (Exactly what larvae eat in the wild is not well understood.) It was not until 1998 that a team led by Hideki Tanaka, a fish biologist at the National Research Institute of Aquaculture, discovered that larvae in tanks would consume a slurry with a base of shark-egg powder. The larvae still only survived for thirty days, but they grew to one-third of an inch before dying.
Continual refinement of the diet extended survival and growth to the two-inch, 250-day mark, when larvae transform into glass eels, ready for freshwater. By 2004 Tanaka’s group had blown past that milestone, too, raising yellow eels of an edible size from birth in captivity. But shark-egg powder is not cheap, and with many shark populations in trouble, it is obviously not a workable or responsible commercial solution. In addition, most of the fertilized eggs still do not produce viable larvae. For now, Tanaka says, mass production on a commercial scale remains out of reach.
Although Europeans don’t consume as much eel as the Japanese, they hold the fish in high regard all over the continent: jellied or stewed in the United Kingdom; smoked in Germany, the Netherlands, and Scandinavia; cooked in a red-wine sauce in France; grilled in Italy—the list goes on. The drop in the European eel population has spurred concern and research activity in recent years. Danish researchers, aiming, like the Japanese, for commercial aquaculture production, have induced sexual maturation and spawning in European eels, and have kept the resulting larvae alive for as long as eighteen days, but not without a struggle. The project’s lead researcher, Jonna Tomkiewicz, an aquatic biologist at the Technical University of Denmark in Charlottenlund, told me, “Right now, we’re where the Japanese were thirty years ago. Their research has received a lot of funding because eels form such a large part of their diet.”
Nevertheless, Tomkiewicz is confident that European eels will eventually be mass-produced. The EU and Denmark recently infused several million euros into her project. Should it succeed, the capacity to breed eels would not only be commercially important, but would also help relieve pressure on the wild stock, she says.
In the U.S., researchers at the University of Massachusetts Dartmouth have bred American eels and sustained the larvae for six days. The program is young—just entering its fourth year—and focuses on understanding the eels’ decline, not on aquaculture. That, no doubt, reflects the economic insignificance of the domestic eel market. Some Asian communities carry on a small trade in eels, and a few Italian-Americans still incorporate them into a traditional Christmas Eve supper. But most Americans will live and die without tasting eel flesh. Quite a comedown in popularity for the fish that was a staple of Native American tribes along the East Coast and its rivers, and that virtually saved the Mayflower pilgrims from starvation their first spring in Massachusetts, in 1621. Eel was avidly consumed as a readily available, inexpensive fish in the U.S. until after World War I, when its presence dwindled, then disappeared from the national table—a change often attributed to modern squeamishness about its snakelike appearance and slime coating. It is hard to think of another food that has fallen so far out of favor in just a century.
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Eels may be on the verge of disappearing from tables everywhere. Japanese, European, and American eels share an alarming reduction in the numbers both of elvers navigating upriver and of adults returning downriver. (Eels are far more easily monitored in freshwater than at sea.) In the mid-1990s, the number of elvers in Japan fell precipitously. Although they have since recovered somewhat, they haven’t returned to former levels, and adult-eel catches have steadily declined. The number of elvers entering European rivers is estimated to have fallen more than 95 percent over the past decade, and authorities have declared the European eel population to be “outside of safe biological limits.” As for American eels, Canadian researchers voiced concern about them as early as the mid-1990s, and their numbers have continued to dwindle. In 1982, a daily mean of more than 25,000 eels used an eel ladder at a dam on the upper Saint Lawrence River, in Cornwall, Ontario. By 2005, that number was down to around 200.
The easy part is counting them. The hard part is figuring out why their numbers are declining. Adverse conditions could be affecting the eel at any of the phases in its wide-ranging and uncharted life cycle. Researchers have proposed various causes: habitat destruction in the form of dams and other barriers to upstream migration; disease or parasites; freshwater pollution; climate change, affecting the water temperature or the ocean currents that carry the leptocephali landward; or any combination thereof. Alternatively, the diminishing numbers of elvers and eels could simply reflect a natural cycle that will reverse itself in time.
Europe has reacted in a stronger fashion than Japan, the U.S., or Canada. New restrictions on the capture and trade of adult and glass eels go into force in the EU during 2009. Some member nations have even temporarily banned eel fishing outright. And this past March, listing of the European eel under Appendix II of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (a.k.a. CITES) took effect, placing additional substantive restrictions on the fishery. In Japan, fishing for adult eels is unrestricted but insignificant; the capture of glass eels and elvers for aquaculture purposes is generally prohibited, with some local exceptions.
For its part, Canada has listed the American eel as a “species of special concern,” but not as threatened or endangered. Its capture is legal in all of its home provinces except Ontario. And after a two-year review, the U.S. Fish and Wildlife Service (USFWS) likewise concluded that the American eel is not an endangered or threatened species. So most of the states it lives in continue to permit the harvest of eels longer than six inches, or past the glass-eel stage. “The American eel has experienced declines due to various causes in parts of its range, but we looked closely at the situation and there are millions and millions of them out there,” says David Perkins, a fisheries manager with the USFWS’s Northeast Region who participated in the review. “The species is not in danger of disappearing.”
Still, it’s probably a good thing that Americans have all but stopped eating eel, or their numbers would undoubtedly be lower. Even though most Americans may never lay eyes on an eel—alive or butterflied—the nation would be a poorer place without them. Eels have coexisted with humans for millennia. Their life of transformations makes our own cradle-to-grave journey in the same aging body seem monotonous. The eel is one of those animals that inspires enduring wonder in people who study it. “I used to work with cod, and when I switched to eels I was surprised by the passionate feelings that surround them,” says David Righton of the Eeliad project. “Now I understand it. They are truly marvelous creatures. In Europe, they have not been very fundable and are only now beginning to receive the attention they should have had a long time ago. We’ll see if it’s soon enough.”