American Eel Anguilla rostrata: Protect or Not Expected September 2015

Summary: Yes or no decision on USFWS protection for American Eel, New World eel spawning in the Sargasso Sea and living in continental and coastal waters, is due.

illustration of American Eel by Duane Raver/US Fish & Wildlife Service: U.S. Fish and Wildlife Service Northeast Region, CC BY SA 2.0, via Flickr

A petition filed in mid-November 2004 by two individuals, Douglas Harold Watts of Augusta, Maine, and Timothy Allan Watts of South Middleborough, Massachusetts, sought protection as an endangered or threatened species for the American eel.

On Jan. 30, 2007, the U.S. Fish and Wildlife Service (USFWS) concluded that, despite declines in some areas, overall population resiliency precluded protection.

On April 30, 2010, the Council for Endangered Species Act Reliability (now renamed as Center for Environmental Science, Accuracy & Reliability) petitioned for federal protection for the American eel, citing a dramatic decrease in present populations due to loss of habitat, overharvesting by commercial and recreational fishers, catastrophic spread of swim bladder parasite (Anguillicolloides crassus), and inadequate regulatory mechanisms.

Despite its slimy appearance, the American Eel has sweet, white flesh in high demand as a gourmet food.

The USFWS’ decision on this petition is expected to be announced by the end of September 2015.

Anguilla rostrata is a New World eel native to the Atlantic coasts of North and South America. The elongated, bony fish claims estuarine, fresh and marine waters from Greenland southward to Brazil.

Common names in English for Anguilla rostrata include: American eel; glass eel; silver eel; and yellow eel.

The genus name, Anguilla, derives from Ancient Greek and Latin diminutives of base words for snake: Ancient Greek: ἔγχελυς, énkhelus, from ἔχις, ékhis; and Latin: anguilla from anguis.

Rostrata, meaning “beaked” in Latin, describes the American eel’s long snout.

With female length ranges of 3 to 5 feet (0.9 to 1.5 meters) and male lengths of 2 to 3 feet (0.6 to 0.9 meters), the American eel presents an elongated, sinuously thin silhouette with a long snout. The conical head features forward-placed eyes, a large mouth with a series of small teeth, and a lower jaw extending beyond the upper jaw. Minute, deeply embedded scales that cover the body are covered with a protective layer of slimy mucous.

Typical of the fish order of Anguilliformes, known as true eels, the American eel lacks pelvic fins. Small pectoral fins emerge close to the head. A long, continuous fin, emerging behind the head at about one-third of the body length from the snout, punctuates the dorsal-ventral, or upperside-underside, silhouette.

Age determines coloration.

In its leptocephalus (Ancient Greek: λεπτόν, leptos, "small" + κεφαλή, kephalé, "head") larval stage, the American eel presents a flat, small, transparent, willow-leaf shape.

Although still transparent, the glass eel stage, with fins and lengths of about 2 to 3 inches (5.08 to 7.62 centimeters), hints at the adult shape.

Gray to green-brown pigmentation characterizes the elver, or juvenile, stage.

The adult stage marks sexual immaturity with yellow green to olive brown coloration.

Bronze-black backs and silver undersides mark sexual maturity.

As a member of the Anguillidae family, the American eel engages in catadromous (Ancient Greek: κατά, kata, “down” + δρόμος, dromos, “course”) migration: hatching in seawater, living in freshwater and returning to seawater for spawning.

The American eel hatches into life in the Sargasso Sea, 2 million square miles of clear, deep blue, warm water between Bermuda and the Azores in the North Atlantic Gyre.

Arrival in the glass eel stage at Atlantic coasts occurs after drifting for almost a year as larvae away from the Sargasso via the Gulf Stream.

Transformation into the elver stage takes place during encounters with the brackish mixture of river and sea water in coastal estuaries.

The yellow eel stage of sexual immaturity, lasting 3 to 40 or more years, develops during settlement in fresh, estuarine or marine waters.

As a migrant in the silver eel stage, the American eel attains sexual maturity and undergoes amazing physical transformations, such as blue-sensitive huge eyes for improved, deep-water vision and increase in number of blood vessels in swim bladder with consequential gas loss reduction for enhanced buoyancy.

The female releases between 500,000 to 4 million-plus eggs into the Sargasso Sea for external fertilization by the male.

The fate of adult females and males after spawning, which has never been witnessed in the wild, is unknown but, presumed to be terminal, beautifully closes a lifespan in which the beginning is the end and the end is the beginning.

The American Eel beguiles as the only freshwater eel in the Western Hemisphere and as a species with an enigmatically complex life cycle.

Rob Roy Ramey, science advisor for the petitioning Center for Environmental Science, Accuracy & Reliability, equates the American eel to “the passenger pigeon of our time.”

line of brown microalgae, or seaweed (Sargassum), in Sargasso Sea, American Eel's spawning homelands: Islands in the Sea 2002, NOAA/OER, Public Domain, via Ocean Explorer/NOAA

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

line of brown microalgae, or seaweed (Sargassum), in Sargasso Sea, American eel's spawning homelands: Islands in the Sea 2002, NOAA/OER, Public Domain, via Ocean Explorer/NOAA @ http://oceanexplorer.noaa.gov/explorations/02sab/logs/aug09/media/lines.html

illustration of American Eel by Duane Raver/US Fish & Wildlife Service: U.S. Fish and Wildlife Service Northeast Region, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/usfwsnortheast/6149968041/

For further information:

“American eel Anguilla rostrata.” U.S. Fish & Wildlife Service > Northeast Region > Newsroom. September 2011.
Available @ http://www.fws.gov/northeast/newsroom/pdf/Americaneel9.26.11.2.pdf

Whittle, Patrick. “Decision soon on listing eels under Endangered Species Act.” Phys.org > Biology > Ecology. Sept. 14, 2015.
Available @ http://phys.org/news/2015-09-decision-eels-endangered-species.html