The American eel, with its long, sinuous, snake-like body, may be one of the most easily identifiable fish of the Atlantic coast. But what is truly remarkable about the eel is not its shape, but its life history.
Eels are one of the few catadromous fish—fish that live out their lives in fresh and brackish waters, but spawn in the ocean—in North America. When tiny “glass eels” fresh from the sea enter coastal estuaries, the males remain in the bays and river mouths, while the females travel deep into the heart of the country, where they may remain for more than 20 years before returning to the ocean for their end-of-life spawning migration to the Sargasso Sea.
Eels were once a valued food fish in the United States, and remain so in Europe and Asia. Thus, they have historically supported a recreational fishery composed of anglers seeking eels for personal consumption. In the past, one of the favored angling techniques didn’t even employ fish hooks. Instead, the sniggler (as eel fishermen are called) would take a needle and strong thread, and sew a mass of earthworms into a ball. The angler then ventured out into the salt marsh at night, and dropped the ball of worms in places likely to hold numbers of eels. When the eels attacked the mass of worms, their thin, backward-facing teeth would tangle in the thread, allowing the fisherman to lift them out of the water and into a basket placed on the bank; once the eels was in the basket, the fisherman would let the line go slack, the eel would free its teeth from the thread, and the process could be repeated for so long as the ball of worms remained intact.
Today, recreational eel fishing has lost much of its popularity. Since 1981, when reasonably reliable estimates of anglers’ landings first became available, annual recreational landings have ranged between 4,000 and 166,000 fish. In recent years, anglers have undoubtedly purchased far more eels for bait than they caught for personal consumption.
There is a substantial commercial fishery for American eels, which harvests eels at various stages during their lives and sells them for various purposes.
The most lucrative fishery is for the so-called “glass eels,” immature eels freshly arrived from their ocean, which are shipped, alive, to Japan, where they are grown out to adult size and sold to produce the sushi dish known as unagi. Fishery managers have determined that harvesting the glass eels can have a detrimental effect on the eel population, and such harvest has been outlawed in most states. Today, most glass eel harvest comes from Maine, although there is also a small legal fishery in South Carolina. Illegal glass eel harvest, spurred by prices that have, at times, exceeded $2,500 per pound, continues in many states, although state and federal enforcement officers have joined together to fight it.
The commercial fishery for adult eels, although legal, is far less lucrative. Annual landings peaked during the 1970s and early 1980s, with nearly 4,000,000 pounds landed in 1979. Since then, harvest has moderated; reported 2015 landings were less than 900,000 pounds. Prices, however, have soared. In 2005, the average ex vessel price for American eels was $3.25 per pound; by 2015, that had increased to well over $15.00; it should be noted, however, that most of that increase can be attributed to a sharp increase in the value of glass eels, not of the adults.
Almost all of the harvest is exported, and with both Asian and European eels very badly overfished, there is a strong demand for the American product.
Range and Biology
American eels can be found all along the east coast of the United States; the population ranges as far south as Venezuela and as far north as the east coast of Canada. Throughout that range, all of the eels constitute a single stock that mixes on the Sargasso Sea spawning grounds. There are no local populations or substocks; instead, the larvae, known as “leptocephali,” drift on ocean currents until brought into proximity with the land, at which point they change form into the so-called “glass eels,” tiny, transparent eels that enter estuaries and, in that form, begin to ascend rivers and streams.
Such glass eels soon take on color, at which time they are known as “elvers”; as they grow larger, and attain harvestable size, they are known as “yellow eels” after the yellow-gold color of their sides.
Although yellow eels can be large, they are still sexually immature. Female eels tend to enter fresh waters and run far upstream; they form a larger part of the population in the northern part of the species’ range, and in areas where the population density is relatively low. Male eels remain in the estuaries or in the lower reaches of rivers; they are relatively more abundant in the southern reaches of the eel’s range, and in places where the density of the eel population is high.
The time it takes yellow eels to mature is not predictable; maturity may take as little as two years, or as many as thirty. However, as yellow eels mature and return to the sea to spawn, they become so-called “silver eels,” light grey eels with white bellies, that assume a form that will carry them to their mid-ocean spawning grounds. Some scientific literature claims that silver eels do not feed. While that is certainly true later in their spawning migration, when their digestive tract atrophies, silver eels newly arrived in the sea continue to feed, and are often caught be anglers seeking other species on rocky bottoms and around inshore wrecks.
No one has ever observed an American eel in the open ocean, on or in transit to the spawning grounds, so most details of such migration remain unknown. However, a satellite tagging study conducted in Canada suggests that eels may not take a direct track to the Sargasso Sea. Instead, they may travel straight across the continental shelf to access deep water and travel in a more-or-less easterly direction, before turning south and heading directly toward the spawning grounds. During the migration, eels may travel as deep as 2,000 feet at times, before rising again into warmer surface waters. It is surmised that such rising and falling path is a compromise meant to minimize predation, which takes a significant toll of the migrating eels, while keeping their bodies at temperatures that will support their metabolism over the long term.
Eels are managed solely by the states, acting together through the Atlantic States Marine Fisheries Commission (ASMFC). There is no federal fishery management plan, nor are there any restrictions placed on eel harvest in federal waters.
Eels’ life history makes them a difficult fish to manage. While managers can strictly limit the harvest of glass eels, and adopt regulations to conserve the population of yellow and silver eels as well, fishing isn’t the only threat that eels face. Dams block upstream passage of the silver eels and elvers; while many find their way around such obstacles, often by means of fish ladders and similar passages, hydroelectric dams may pose a much greater threat when the adult eels are migrating to the sea, and end up being killed when they swim into turbines instead of the same passageways that gave them access to the headwaters years before. An alien nematode, which parasitizes the swim bladders of eels, has also invaded North American waters in recent decades; although it does not seem to do significant harm to yellow eels, there is speculation that, by damaging the swim bladder, it may make it more difficult for migrating silver eels to reach their spawning grounds.
ASMFC considers the American eel stock to be “depleted,” with abundance trending downward.