American eel
The American eel is a fascinating aquatic species predominantly found along the east coast of North America, where it inhabits freshwater and estuarine environments. Known for its unique life cycle, the American eel migrates to the Sargasso Sea in the Atlantic Ocean to spawn after several years spent in rivers and lakes. Adult males typically migrate when they are about four to eight years old, while females leave at seven to twelve years. This migration occurs in the fall, and the adults die shortly after spawning, releasing thousands of eggs into the water.
These eels exhibit remarkable adaptations, such as the ability to breathe through their skin and slither over land during migration. Their young, called leptocephali, begin life as translucent, leaf-like forms and gradually transform into eel-like shapes as they return to North America. While American eels are valued for human consumption and as bait in sport fishing, their populations have faced significant declines, prompting the International Union for Conservation of Nature (IUCN) to classify them as endangered. The decline is largely attributed to increased demand following the contamination of the Asian eel population and restrictions on exports of European eels. Understanding the complex life of the American eel is essential for appreciating its ecological role and the conservation challenges it faces.
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American eel
American eels are aquatic bottom dwellers typically found on the east coast of North America. They live in fresh water and estuaries but leave these habitats to enter the Atlantic Ocean and then spends one to two years migrating to various freshwater bodies in the United States. They live in these freshwater environments for several years and then migrate back to the sea in order to reproduce and die. This species of fish is very similar to the European eel.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Anguillidae
Genus: Anguilla
Species: Rostrata
American eels have broad snouts and eat fish, while others have pointed snouts and eat various small creatures. Both types are night-feeders and may feed on carrion, dead animal flesh, or on live prey. Sometimes they even eat each other, which is called cannibalism. During their seaward migration all the eels stop feeding and survive on their bodies' stored fat. They are also able to slide and slither over moist ground for periods of time as they migrate. They are able to breathe 60 percent of their oxygen through their skin, which also keeps in moisture so they do not die.
When an adult male American eel is four to eight years old it is ready to begin its long journey from its freshwater home to the Sargasso Sea. A female makes the same trip when she is 7 to 12 years old. A fully-grown adult making this migration may be up to five feet (1 1/2 meters) in length. From the rivers, lakes, ponds, and streams all across the eastern United States the American eels swim toward the sea, knowing exactly where they are going.
The migration, which begins in the fall, ends a few months later when the eels reach the Sargasso Sea in the western Atlantic Ocean. This is the spawning, or egg-laying, site for the eels. Not all the eels within their range travel to this site, but a great many do make the trip. The female spawns, or releases thousands, or possibly even millions, of eggs into the water which the male fertilizes. Neither of the adults live to raise the young but die shortly after spawning.
When the young hatch they do not look like eels, but like thin, short, clear willow leaves. The baby eels are called leptocephali (the singular is leptocephalus). After hatching they begin floating and swimming on the Gulf Stream currents toward North America, a journey which lasts up to one year. As they travel they begin changing into a more adult, eel-like form. Shortly before they reach the coast their bodies shorten and become thin, similar to worms or small snakes. Their six-inch (15 centimeter) bodies then also darken in color.
Young male eels remain near the coast in estuaries, or river mouths, and freshwater swamps, lakes, and streams. Females swim farther upstream and inland to lakes and rivers. Over the next several years they grow until they are ready to make the return migration to the sea to spawn.
Like their European relatives, Americans eels are a food source for humans and are also frequently used as bait for sport fishing, for example, to catch striped bass.
The life span of American eels is generally 4 to 12 years, but some may live up to 20 years if they did not migrate and spawn.
In 2014, the International Union for Conservation of Nature (IUCN) added the American eel to its Red List, a list of endangered species threatened to go extinct. The Asian and European eels are also on the list. All three species have seen a population decline due to human market demands. The demand for American eel occurred after the 2011 tsunami in Japan contaminated and killed off the Asian eel population and after Europeans banned the exports in 2015. This demand led to the population decline and subsequent endangered status.
Bibliography
“American Eel.” U.S. Fish & Wildlife Service, www.fws.gov/species/american-eel-anguilla-rostrata. Accessed 20 Mar. 2024.
Sneed, Annie. “American Eel Is in Danger of Extinction.” Scientific American, 1 Dec. 2014, www.scientificamerican.com/article/american-eel-is-in-danger-of-extinction/. Accessed 20 Mar. 2024