American eels were once an important food source for the Abenaki peoples of New Hampshire and Vermont. When autumn arrived eels were captured in stone weirs as they migrated down river. Traps consisted of two short lines of rocks that met in the shape of a “V” pointing downstream. An eel pot – a round basket with a wide mouth – was placed where the rocks converged.
The catch consisted mostly of reproductively mature female American eels (called “silver eels”) that were swimming to mid-winter spawning grounds in the Sargasso Sea, south of Bermuda. After hatching, tiny, immature eels drift northward on ocean currents. They eventually turn into elvers that begin a springtime journey toward estuaries and rivers.
Eels are only about an inch long when they reach the coast. Males often remain in brackish waters while the diminutive females swim slowly upstream until they enter the deep waters of lakes. There they live for 6-30 years, feeding at night on small fish, frogs, crustaceans, insects, worms, and shellfish. Females, which are larger than males, can grow to over 3 feet long. In autumn, mature silver eels begin a nocturnal journey downstream. After entering the ocean, they stop eating and swim back to the Sargasso Sea – there to spawn – and die. Each female produces 15-20 million eggs.
From Lake Champlain to the Chesapeake Bay, however, and from Lake Ontario to the Connecticut River, eel populations are falling. Eels are still found in southern New Hampshire and Vermont, but they are scarce, or have disappeared, in our northern rivers and lakes.
Why the decline? “Eels were shut off from their historic growing areas beginning with the first dams across the Connecticut River in the 1790s,” says David Deen, River Steward for the Connecticut River Watershed Council. Young eels can’t leap obstacles the way salmon and shad can. “They make their way by pushing against the rough surface of rocks where there is a light flow of water. Eel ladders are like indoor-outdoor carpeting with a trickle flow of water.” A number of hydropower dams have installed eel ladders, and existing fish ladders are being modified to accommodate eels.
At one hydroelectric dam in the Upper St. Lawrence River, the number of eels passing dropped from 27,500 per day in 1982 to 50 in 2004. In 2002, a mere 275 American eels passed the Holyoke Dam in Massachusetts, but by 2005, there were none. The U.S. Fish and Wildlife Service recently completed a study of the American eel (Anguilla rostrata) and concluded that, although some local and regional eel populations (like ours in the Northeast) have declined, the overall population is not endangered and does not warrant protection under the Endangered Species Act.
Hydroelectric dams are particularly harmful to seagoing females. Between 80 and 100 percent can be injured passing through hydro-turbine blades, with up to half being killed. Many eels must traverse several dams while migrating downstream. Some hydropower companies now shut turbines off at night during peak autumn eel migration. Several defunct dams have been removed, restoring eel habitat and improving water quality.
Overharvesting may also be playing a role. The use of eels for food is increasing worldwide especially in Asia and Europe, where eel is a delicacy. The price for elvers can exceed $300
per pound. Because eels spawn once in a lifetime, individuals that are caught have never reproduced. In the Northeast, two states – Maine and New York – permit the commercial harvest of silver eels.
Habitat loss and water pollution affect eels adversely. Toxins that accumulate in eel fat can reduce growth, decrease reproduction, threaten the survival of young, and lower resistance to diseases and parasites. Pollution can disorient eels and reduce both their ability to mate and their endurance for swimming. The concentrations of mercury, PCBs, and other contaminants in eels from Lake Champlain are so high that women of childbearing age and children under 15 are advised to abstain from eating them.
Perhaps, with concerted effort, American eels will one day be restored to their historic range in New Hampshire and Vermont. At the local level, many sewage treatment plants and drainage systems are being upgraded to prevent stormwater runoff from mixing with sewage and entering waterways during heavy rains. And, in some towns, highway crews have begun to install culverts that are large enough, and with both ends submerged, so that eels can pass through.
Re-establishing the eel would enable native peoples to practice a venerable tradition. In the 1980s, members of the Abenaki Nation of Vermont wanted to start a limited eel fishery in Lake Champlain, but scarce eels and poor market conditions made the venture unsustainable. Eels clearly remind us that our own well being is closely intertwined with the fate of the natural world.