The first time I was served eel, more than ten years ago, I was not expecting it. It arrived as part of a sushi combo platter, which I had gotten into the habit of ordering in the hopes of becoming a more adventurous eater. (It also relieved me of the burden of choice.) In addition to many varieties of raw fish, I tried salmon roe, octopus, egg custard, and, eventually, a slab of cooked meat, slathered in a teriyaki-like brown sauce, perched atop a finger of vinegared rice, and belted with a strip of seaweed. Upon hearing that this was “barbecued eel,” I’m sorry to say that I reacted like a six-year-old: “Nope, sounds like a gross animal I wouldn’t want to eat!” Eel fell into my “mystery seafood” category, which had once included mussels and sea urchin: prohibitively weird until proven delicious. As far as I was concerned, eels were slimy, mysterious creatures—serpentine, or perhaps amphibian, but certainly not piscine. I was further tripped up by the word “barbecued,” which brought to mind the tangy all-American sauce usually reserved for pork ribs. The combination sounded disgusting.
But unagi, as freshwater eel is called in Japanese, turned out to be quite tasty. “Barbecued” meant, happily, prepared kabayaki-style: skewered, glazed in a sweet sauce of mirin, soy, and sugar, and grilled to smoky perfection. In Japan, more than a hundred thousand tons of eel are consumed annually (about seventy per cent of the worldwide eel catch), mostly kabayaki-style and during the hottest days of midsummer, on and around the Day of the Ox on the Chinese zodiac, in late July (a tradition invented by the owner of an eel restaurant in the eighteenth century). The oily flesh, rich in vitamins A and E as well as omega-3s and antioxidants, is said to impart stamina to stave off summer fatigue. In the U.K., jellied eel—chopped and boiled in stock that cools and sets—is a London delicacy that is currently enjoying a surge of popularity thanks to the supermarket chain Tesco, which started selling it outside of the city. In New Zealand, eel is a traditional Māori food, baked in a covered basket or roasted in wrappings made of leaves. Across Eastern Europe and parts of Scandinavia, eel is eaten smoked.
Eels are, in fact, fish, and the freshwater species fall under the genus Anguilla, which evolved fifty million years ago. There are more than a dozen freshwater species, but the varieties that have been most widely fished and eaten are American (A. rostrata), European (A. anguilla), and Japanese (A. japonica). In recent decades, the populations of all three have declined as much as ninety-nine per cent, due to a suite of factors: coastal development, fishing, and hydropower dams, as well as disease and predation. Both the Japanese and European species have been listed as endangered by the International Union for the Conservation of Nature.
And yet, according to James Prosek, an artist, naturalist, and the author of the book “Eels,” the American eel will never be listed under the Endangered Species Act. The E.S.A, Prosek told me last week, “works well for creatures that could go down to a population of six hundred, and eels will never get down to that. Maybe a million, and that won’t be enough to sustain collective consciousness”—it won’t sound bad enough to make the public care. But if the American eel population gets down to even a million, it will be in grave danger, as will its ecosystem. Prosek likens the threat against the eel to the fate of thepassenger pigeon, which was once the most numerous bird in North America, before it went extinct in 1914. Eels once accounted for as much as fifty per cent of the total fish biomass of East Coast rivers and streams, and dozens of other animals depend on the eel.* In the Susquehanna River, they are prey for osprey and raccoons and a ride upriver for the larvae of freshwater mussels, which hitch onto them before settling in and getting down the business of water filtration.
Part of the problem is that it’s hard to get worked up about eels the way we do for pandas or salmon. “Their sliminess and association with the snake and the phallus, as well as a general tendency to stir human uneasiness, have made eels a tough species to champion,” Prosek writes in his book. Freshwater eels are rather jolie laide as far as fish go: they lack pelvic fins, some species have no pectoral fins, and their dorsal, anal, and caudal fins are fused into one long ribbon framing the length of their bodies. Despite having fins and scales, eels are not kosher, because their scales cannot be removed cleanly. Their bodies are covered in a mucosal slime, making them near impossible to grasp or impale (most eel spears have tines). The average American fisherman is more likely to throw an eel back or use it as bait than to keep it for food.
But eels are some of the planet’s most intriguing creatures. They are nocturnal, and they can absorb oxygen through their skin, allowing them to spend time out of the water, slithering across land and over barriers. American eels can live as long as forty years; European ones can live for eighty. Both are catadromous, meaning that they spawn in the sea but spend their juvenile and adult lives in freshwater. Their blood is toxic to humans—research using the toxin derived from it led to the Nobel Prize-winning discovery of anaphylaxis—which is why they’re always served cooked. They have weak jaws and small teeth, so in order to break apart their food they spin their bodies wildly. They can swim backward. Most curious of all, every American and European eel is born in the same place in the middle of the Atlantic Ocean, where, at the end of their lives, they return to reproduce and die: the Sargasso Sea.
The name looks like something out of a medieval fairy tale, but the Sargasso is a two-million-square-mile whorl in the Atlantic Ocean, south of Bermuda, and bounded clockwise by currents: the Gulf Stream, the North Atlantic, the Canary, and the North Equatorial. It is named for sargassum, a type of seaweed found in its waters, which are exceptionally blue (there is a fountain-pen ink named after their color). Biologists believe that the warm, salty, largely calm conditions in the Sargasso make it ideally suited for eel spawning. The Caribbean island of Anguilla, so named because its shape resembles an eel, happens to be right next door to nature’s largest eel hatchery.
That all rostrata and anguilla have a common birthplace wasn’t known until recently, because for ages no one knew how eels reproduced, or whether they even did so at all. No one has ever witnessed adult eels spawning in the wild. Aristotle believed that they were sexless; repeated dissections failed to reveal any gametes. He classified them as spontaneous generators, creatures that grew from the “guts of the earth.” But the eels he was catching, in a lagoon between modern-day Turkey and the island of Lesbos, were just sexually immature. The Sargasso was pinpointed as the breeding ground only a century ago, by the Danish biologist Johannes Schmidt, who spent twenty years searching for tinier and tinier eel larvae in the Atlantic Ocean. (The spawning grounds of the Japanese eel were found in 1991, after six decades of searching, and those of the New Zealand longfin eel have yet to be discovered.) Theleptocephalus (meaning “slim head”)—a long, flat, transparent sea creature—was long thought to be a distinct species, until one was kept in captivity long enough to metamorphose into an eel; it was merely a larva.
Every year, after hatching, the tiny eels of the Sargasso Sea swim off toward land. The American eels make it up to the waters around Florida in January, reaching New Jersey by February, and Maine by March or April. It is not known how the delicate larvae know where to swim—what tells anguilla to head for Europe and rostrata to go to the eastern seaboard? Do they know where their parents came from? There is strong evidence that they use magnetism as a homing device—baby eels have tiny crystals of iron in their heads. As they travel north, the larvae become worm-like creatures known as glass eels. As they enter freshwater streams and begin eating insects and worms, they gain pigment and become elvers, a word that is likely a corruption of “eel-fares” or “eel-fairs,” terms that describe the annual upstream mass migration of thousands of juvenile eels in rivers across the northern hemisphere, from the Thames to the Mississippi.
Glass eels and elvers, which can be caught at the mouths of rivers in the spring, are the eels valued most highly by fishermen. They’re sometimes eaten straight away—elvers fried in olive oil with garlic and red pepper are a Basque delicacy known as angulas—but much more commonly they are raised to maturity in large tanks. Because so much of eel reproduction remains a mystery, no one has been able to breed them in captivity on a commercial scale (though the Japanese have had success in smaller numbers). As the population of the Japanese eel has dwindled, the eel market has subsisted largely on glass eels and elvers caught in North America and then farm-raised (the cheapest, fastest way to grow eels is in heated tanks—they’ll eat more in warm water) in China or South Korea, where they’re slaughtered, cleaned, skewered, and grilled en masse. It is very likely that the unagi you eat in New York or Los Angeles took not one but two international flights to reach your plate.
Google the phrase “glass eels” and you’ll find a spate of recent articles about the gold rush on them in North America. In 2010, the E.U. banned export of the European eel, and in 2011 the Tōhoku earthquake and the resulting tsunami wiped out the already depleted stocks at many of Japan’s eel farms. In Maine and South Carolina, the only states with legal commercial elver fishing, the price of glass eels increased tenfold in three years. It peaked, at twenty-six hundred dollars a pound, in 2012 and again in 2013; that season, Buzzfeed reported on rampant poaching, nighttime standoffs, and armed fishermen. Last Thursday, I called Pat Bryant, an eel fisher in Nobleboro, Maine, who had just come back from the water. (Glass-eel season opens in late March and lasts until the end of May.) When I asked her what glass eels were going for this year, she laughed. She said, “What are they actually worth or what are we having to pay for them?” When she started fishing glass eels, in 1978, they went for about ten dollars per pound. Two weeks ago, fishermen were being paid two thousand and fifty dollars per pound by buyers sent from farms in Asia. During the high season, eel is the third-largest import to the Tsukiji fish market in Tokyo.
In the U.S., there is very little domestic demand for older eels (called yellow eels because of their yellowish-brown pigmentation), so there are very few licensed adult-eel fishermen left. Eels can spend as long as ten or even twenty years in freshwater before entering their final life stage and migrating back out to sea. We don’t know what calls them back whence they came, but we know that, before they migrate, their bodies begin to change to adjust to the deeper, darker, colder water that they will encounter in the ocean. They lengthen and fatten. Their heads compress and their eyes enlarge. Rachel Carson described the metamorphosis of a yellow eel into a “silver eel” as a dignified aging process: “Gradually the river garb of olive brown is changed for a coat of glistening black with under parts of silver: This is the dress worn only by eels about to undertake the far journey to the Sargasso.”
The very end of an eel’s life is a mystery—no silver eel has ever been observed in the open ocean. (They are difficult to tag for tracking in unobtrusive ways, though it has been tried.) Their journey back to the Sargasso is a sacrifice to the next generation: they leave the rivers carrying only enough fat and protein for a one-way trip. The trip is not easy, thanks to the tens of thousands of dams along the eastern seaboard. It’s only fortunate juveniles that make it upstream in the first place (thanks largely to the aid of fish ladders), and then they face the danger of being chewed up by the turbines in hydropower dams on their way back down as adults. Even if they do make it out, the ocean holds its own obstacles. In an interview last week, Jim McCleave, a preëminent American eel biologist who has been to the Sargasso eight times, recalled his first trip: “We’re a thousand miles from land and here are all these coffee cups, pop bottles, soda bottles, junk way out in the middle of nowhere.” The slow, calm waters of the Sargasso have collected a significant patch of non-biodegradable waste.
The survival of the freshwater eel depends on high numbers of silver eels making it out to sea. According to McCleave, there is good evidence that eels mate along very specific fronts or currents, which have a particular salinity and water temperature, and lack predators. Because the Sargasso is so overwhelmingly vast, he warned, “if the population gets too low, and even if the adults can find these oceanographic features, they may be so scattered” that they won’t succeed in finding a mate. Both Prosek and McCleave say that they eat eel occasionally, and neither begrudges Japan its culinary traditions. Prosek would prefer to see eels raised more sustainably, however; he suggests harvesting fewer glass eels in North America, and even raising some of them locally to supply the domestic sushi market. It would be a start for the lowly eel, whose poetic migrations—from life to death and back—we have thwarted at every step of the way.