The Incredible Edible Eel

The mysterious fish faces a troubling future from overfishing to environmental factors.


Photograph by Heather Perry

Skip Zink has been a field biologist with the Maine Department of Marine Resources for twenty-five years. His specialty for the last fifteen has been the American eel, Anguilla 
rostrata, one of the most mysterious of fish.

When he sets out to study them in the field, walking stream banks and river courses, contemplating the speed and pitch of water over the lips of dams, circling the muck of brackish pools, and bushwhacking into the outflows of lakes, he’s bound to get wet, and occasionally he runs into someone who asks him what he’s doing.

“If they don’t know a thing about eels,” he says, “I tell them. I open their eyes to the story — the long migrations, the fact that no one really knows what drives them — and most of the time they’ll say, ‘Wow, I never knew that!’ They think it’s great.”

We’re in a storage shed, a one-story edifice on Beech Street in Hallowell, a short walk from the Bureau of Sea-Run Fisheries and Habitat building. It is dark inside, and even when Zink snaps on a light, it feels a bit underwater, crepuscular, the sort of environment favored by eels.

He is rummaging in a room stacked with fine-mesh dip nets, eel pots, and fyke nets. Leaning forward, he yanks one of the fyke nets off a pile and spreads it out on the hall floor.

Most of us who live on the coast have seen these contraptions set by fishermen in the spring along the shallow banks of our hometown rivers. Up close, this one looks like a huge and very dead fruit bat, its enormous wings weighted with sinkers on the trailing edge. In the water, the wings are spread and anchored, and the net gathers into its embrace tiny migrating eels, called glass eels, as they nudge and curl and poke their way upstream from saltwater. They are no more than two to three inches long, as clear as window glass, with big black eyes and a frill of red gills and thin black lines of gut and spine, and a minute, beating red heart. They slide into the throat of the net, pass through a nylon mesh sieve, swim into a second throat to arrive at the cod: a fabric bag tied with a rope, from which there is no escape.

Zink holds up a dip net with a long wooden handle, also used to catch glass eels, and in his other hand, an eel pot that looks like a small lobster trap. Fishermen bait these pots with herring or worms and drop them into lakes and rivers for yellow eels, the adolescents that spend years here slowly growing to maturity.

What we won’t see in this shed is an eel weir, that ancient, and variously-made construction, invented and reinvented by every human culture that has lived close to eels. Reportedly, you can still find traces of the funnel shapes of stone weirs the Native people built into the beds of rivers on the East Coast to catch silver eels that move at night under, as the Irish say, the dark of the moon. These black-backed, silver-bellied fish are ready to go to the sea in late fall, and were, according to some, the most precious gift the Wampanoags gave to the Pilgrims to keep them from starving in their New World.

Zink leads the way down the hall and into another room where he stores what look like wooden slides no more than five-feet tall, with movable back legs and sheets of erosion mat tacked to the beds. He carries these portable ramps into the field, into places where dams and other impediments prohibit upstream eel migration, choosing a site on a dam’s downside that looks eel-friendly to his educated eye. He steadies the legs, sets up a pump that trickles water down them, and returns in the evening with a flashlight to see if eels are climbing the mat in an attempt to ascend the river. Sometimes he has to move the ramps and the pumps, place them at another angle, or along the opposite bank. He is patient, waiting for the eels to tell him where they would like to begin their climb, and when they let him know, he designs a plan that allows some kind of passage from that point, perhaps using a spillway, a bypass channel, or permanent ramps to help these fish get upriver to where they want to go.

“I’ve seen the eels go straight up the wet face of a dam until they come to the top where the water just flicks them off and they fall back down. The ones that survive are right back, trying all over again.”

A field biologist who gives his best time and attention to the American eel must contend with compromised river systems, exploitive fisheries, public indifference, the many unsolved puzzles of eel biology and behavior, and the plain fact that an eel isn’t a salmon. A salmon is a glamour-puss.

American eels have five life phases: larvae, glass eel, elver, immature yellow eel, and the mature silver eel.

When my children were small, we found elvers — the little black eels — hiding between the rocks on the low tide gravel bar to Little Moose Island at Schoodic Point. We’d lift a rock, I’d catch an elver, pour water and fish into my children’s cupped and waiting hands: for a few seconds they held a thin, pitch-black, four-inch-long eel, its pectoral fins spread, its delicate tail weaving, tickling their skin. Then, gently, they’d pour the eel back where it belonged.

We didn’t know then that these young fish had made a journey of magical proportions.

In 1886, a French zoologist dropped a saltwater leaf-shaped fish, about an inch and a half long, into his aquarium, where it turned into a glass eel, a startling metamorphosis. But it wasn’t until 1920 that Danish biologist Johannes Schmidt, tracking those larval fishes through the Atlantic, came upon individuals of the smallest size. He found them in the North Atlantic’s Sargasso Sea, a gyre approximately seven hundred miles wide and two thousand miles long, surrounded by four ocean currents.

Eels are born in the Sargasso. We have never seen this. We see the tiny larvae — the leptocephalus — in the floating Sargassum weed, but not the arrival of the adult eels there, nor their mating, nor their eggs, nor the hatching of those eggs.

The newborn larvae rise to the surface, and soon begin to drift on the Gulf Stream toward North America. A journey of thousands of miles, it can take more than a year for them to veer off from the current and head toward shore, toward fresh water. What makes a tiny, leaf-shaped fish choose Florida or North Carolina over Maine or Canada? We don’t know. Biologists point out that adult salmon, returning to their birth streams and rivers, follow the scent of those familiar home waters, but a larval eel has never smelled fresh water. And, presumably, its parents could have grown up in completely different places: one in a river on the Gaspé, the other in a stream in Georgia.

The larvae of the European eel also head west on the Gulf Stream, which eventually circles into the North Sea and down through the Azores, dropping them off throughout coastal Europe.

The American eel has about 109 vertebrae, give or take a few. The European eel has about 115 — give or take. We can see these small, open-ended variations, and there are others like them, which may indicate that the two species were once one, and became separated due to continental drift. They are fish of such ancient beginnings.

Aristotle believed that eels were born from “the bowels of the earth,” a fecund mix of mud and water, not as odd a determination as one might think, given that no sexually mature eels had ever been found. Today, we know that the silver eels with a ribbon-like structure in their gut will become females, and those with a lobed structure will be males. The transformation into sexually mature fish carrying eggs and milt happens deep in the Atlantic, on the long trek back to their breeding site.

Female eels are much larger than males, and migrate back to the Sargasso when they are much older. The males, under eighteen inches in length, are found in estuaries and shallow rivers, and most of them tend to live farther south. Almost all our lake eels are female, and as you go north, the percentage of female eels over males increases dramatically. Why? Does the environment the young eels live in determine their sex? Or do the feeding and maturation needs of each determine their choice? Or is it something else entirely?

The yellow eel can live for fifteen to twenty years in our rivers and lakes. The females can grow to more than three feet in length. Eagles, osprey, snapping turtles, largemouth bass, and striped bass feed on eels. They, in turn, feed on invertebrates, frogs, smaller eels, other fish, such as alewives, and carrion.

In winter, Zink says, the eels hole up. “They are in survival mode,” he says. “When it gets cold they’re not actively feeding. That’s why their growth in northern waters is slow.” When eels are ready to migrate back to the Sargasso Sea, he says, they undergo a second metamorphosis. Their eyes enlarge. Their pectoral fins get bigger, wider, and longer. Their digestive track disintegrates. Their skin thickens. They put on fat. They become sleek, black-backed, silver-bellied, long-distance, deep-water swimmers, and in late fall, thousands of them begin their journey to the ocean to mate and to die.

Because eels are catadromous fish — they live in freshwater and migrate to the sea to breed and spawn — and because they can breathe through their skin as well as their gills, making it possible for them to travel over wet surfaces on land, they require special kinds of fish passage upstream, quite different from the ones that help salmon and alewives. Zink has worked to provide eels in Maine with such passages. It is now the downstream migration of the silver eels that is the most precarious.

“We worked to get them up,” Zink says. “Now we work to get them down. Some things take a long time and a lot of negotiation.”

When the eels swim into the turbines of hydro-electric dams, an entire river’s fish run can be destroyed in a couple of nights, the bodies of dead and dying eels piling up at the dam’s downside.

Some companies have been persuaded to slow the rotation of the blades on the nights of eel migration, which gives the fish a fighting chance to get through the turbines unharmed.

For centuries these fish have been eaten in Europe, Japan, and China. Despite the grateful Pilgrims, most modern Americans have never acquired a taste for eel, although this may be changing. Popular Japanese restaurants in this country have introduced us to unadon, an elegant dish presented in a lacquered box that contains hot grilled eel on a bed of rice, and many kinds of sushi are also made with eel.

In Maine, yellow eels are caught in eel pots for bait, the silver eels are caught in weirs for specialty markets, here and in Canada, and the glass eels are trapped in fyke nets by the thousands for export to Japanese and Chinese fish farms.

“The eels are hit at three stages. They don’t get much of a break,” Zink says. “But sometimes the market for the glass eels falls, and nobody sets fyke nets that year — it’s not worth it to them — and that’s the year the eel wins. Japan has overfished its glass eels, and they come looking to us to supply them. Or the Chinese come to buy from us and raise them commercially to sell to Japan.”

All the other East Coast states have closed their glass eel fishery, except for North Carolina, which issues a handful of licenses. Maine identifies itself as a state with a vibrant fishing culture, which is true, but that includes catching a number of species in decline.

“You don’t want to lose the fishermen,” Zink explains, “What about all the fishermen who need the work?” When he started to study eels, he estimates that about four thousand licenses were given out to glass eel fishermen that year. “It was like the Wild West,” he says.

Today, it is down to four hundred, and the only people allowed a license are those who have held one before. “It’s pretty much a closed fishery now. But, sure, if you think about it, we are a species that tends to want to take too much,” he says. “It doesn’t matter if it’s trees or fish.”

If the U.S. Fish and Wildlife Service and the National Marine fisheries Service decide to list the American eel as a federally endangered species along the entire East Coast, our fishery in Maine will close down immediately.

That may not solve the problem. Although eels may be one of the most difficult wild fish to count, it is no secret that populations have plummeted both here and in Europe.

Overfishing is an obvious cause, but there may be a more insidious, intractable problem: climate change. If the four currents that bracket the Sargasso Sea are shifting, affecting the mating territories and the nurseries of the American and European eels, how would we know? We haven’t even found those places yet. And, more to the point, how would we stop such monumental change?

The Chinese and Japanese are attempting to breed eels in captivity and raise them to maturity, a loop that would obviate any need for a wild fishery, but they haven’t been able to do it. We can replicate the life cycle of the salmon — not the American eel. Even when eels are inoculated with hormones to bring them to sexual maturity in the laboratory, the offspring are often mis-shapened and waste away in the carefully controlled vats. For now, we’re stumped.

By the time they are harvested, the Maine glass eels that have been sent to China and raised in commercial farms contain significant levels of pesticides and fungicides from those farming practices. The water used to raise them often flows right back into the rivers and lakes it came from, extending the footprint of pollution. And, lastly, these commercially-raised fish are fed on ocean fish, tons of them, depleting healthy wild stocks to raise unhealthy, but tasty eels.

Why should we care?

We should care because there are some mysteries still left in this world of ours. As Zink says, “We know more about the moon than we do about the oceans. The oceans are still very big places. I kind of like that.”

One mystery we haven’t figured out is the life of the American eel. It comes to us from a very big ocean and spends years within our hometown streams and rivers, our lakes and estuaries, hidden in the watery shadows by day, swimming in the open water by night. It is so close, and, yet, mostly unknown to us, although its life has fed human lives for countless generations of eels and men.