Olive to brown on the back, fading to greenish yellow on sides, gray or white underbody; snakelike body with small conical head and broad mouth; paired bluntly rounded pectoral fins; long, continuous dorsal, caudal and anal fin. Grows to 5-6 feet and weighs 10-15 pounds.
Mainly in Mississippi River and its larger tributaries.
Fish, invertebrates and terrestial organisms washed into the water.
State Records are not documented for non-game species.
Eels spawn in the ocean, and females return to mature; however, the location where eels spawn has never been discovered, and eel eggs have never been sampled from the ocean.
In Iowa, the American Eel inhabits the Mississippi River and its larger tributaries. Its presence has also been documented in the Missouri River. In the Mississippi River, the American eel is uncommon in the entire reach that borders Iowa. This fish is rather rare in collections, but does not appear to be on the verge of extirpation.
The American Eel is not considered a threatened species in Iowa, but it is quite difficult to assess its population because it is difficult to capture with conventional sampling methods. Construction of the impassable flood control dams on the Des Moines, Iowa and Chariton Rivers have undoubtedly restricted migration in these drainages, but the impact on resident populations is unknown. Even though the eel is not abundant in its Iowa range, resident populations do not appear to be on the decline.
Color of the American Eel varies considerably, usually from olive to brown and the back, fading to greenish yellow on the sides, and gray or whitish beneath. The body is long and slender, resembling a snake more than a fish. The head is small and conical with a broad mouth that contains numerous sharp teeth. The fins are peculiar to this fish with paired, bluntly rounded pectorals and single continuous dorsal, caudal and anal fins.
The eel prefers fairly deep, mud-bottomed waters, which probably accounts for the reason they are most often found in the larger rivers. Weight rarely exceeds a couple of pounds, but some individuals, especially if landlocked, may reach a maximum of 5 to 6 feet and weigh 10 to 15 pounds.
Eels, because of their snake-like movements, are able to navigate in extremely shallow marshy areas. They are largely nocturnal feeders consuming mainly fish, invertebrates and terrestrial organisms that are washed into the water. As a nocturnal feeder, the American eel spends daytime hours in deep pools near logs, boulders, or other cover. Eels are carnivores and, contrary to earlier thinking, seek living prey rather than dead organic matter for food.
The American Eel is commonly found in deep, quiet navigational pools of the Mississippi River. In the Ozarks region of Missouri, it seeks medium to large-sized streams with continuous flow and moderately clear water. It is able to withstand significant turbidity and although it is known to venture on land to find prey and circumvent small dams or waterfalls, inland migration north of Louisiana has been limited by the construction of large dams.
The spawning life cycle of the American Eel is endemic to this species. Eels are catadromous, which means they spawn in saltwater and mature in freshwater. The cycle begins with the female maturing in freshwater streams over a period lasting from 5 to 20 years. Upon maturity they migrate downstream to the sea in autumn. Females are joined by the males, which have remained in the estuaries, never growing much more than 2 feet in length. The suspected area of spawning for all freshwater eels is in the southwestern North Atlantic Ocean east of the Bahamas and southwest of Bermuda in a region often referred to as the Sargasso Sea.
After spawning, mature males and females have not been observed near spawning grounds and are presumed to die. Eggs of the eel have never been sampled in the ocean, but it has been estimated a single female may produce from 5 to 20 million eggs. It takes at least a year of travel for the transparent, leaf-like eel larvae to reach freshwater streams along the coast of North America. Larval eels are called leptocephalus larvae and move via oceanic currents. Upon reaching the coast, these larvae metamorphose into 2 l/2 inch long worm-like transparent "glass eels" and begin ascending coastal streams to their eventual home to mature.
Fishing for eel is unimportant in Iowa, and most of those caught are taken incidental to other species. The flesh of eel, while very rich, is said to be delicious. It is sometimes prepared by pan-frying but is more often smoked, pickled or jellied. Smoked eel is by far the most accepted and is considered a delicacy. There is little demand for eels in this section of the country.
Recent stream sampling has not resulted in the discovery of any individual American Eels. Complete stream sampling information is available from Iowa DNR's biological monitoring and assessment program.
The American Eel is viewed as vulnerable according to the Iowa Wildlife Action Plan, but it is not on Iowa's endangered, threatened, or special concern species list (571 IAC 77.2(2) (2015)).
Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.
Iowa Department of Natural Resources, Iowa Wildlife Action Plan
Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames
Illustration by Maynard Reece, from Iowa Fish and Fishing.