American Eel

Characteristics

Color of the American Eel varies, usually from olive to brown on the back, fading to greenish yellow on the sides, and gray or whitish beneath. Its body is long and slender, looking more like a snake than a fish. Its head is small and pointed with a broad mouth with numerous sharp teeth. The fins are peculiar to this fish with paired, bluntly rounded pectorals and single continuous dorsal, caudal and anal fins. Grows to 5-6 feet and weighs 10-15 pounds.

Distribution

Mainly in Mississippi River and its larger tributaries.

Foods

Fish, invertebrates and terrestrial organisms washed into the water.

State Record

State Records are not documented for non-game species.

Expert Tip

Eels spawn in the ocean, and females return to mature; where eels spawn has never been discovered, and eel eggs have never been sampled from the ocean.

Details

In Iowa, the American Eel lives in the Mississippi River and its larger tributaries. It 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 rare in collections, but does not appear to be on the edge of extirpation.

The American Eel is not considered a threatened species in Iowa, but it is difficult to measure its population because it is hard to capture with conventional sampling methods. Construction of the impassable flood control dams on the Des Moines, Iowa and Chariton Rivers have 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 declining.

The American Eel prefers fairly deep, mud-bottomed waters, which is why they are most often found in the larger rivers. It rarely weighs more than a couple of pounds, but some eels, 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, can navigate in extremely shallow marshy areas.  They eat mostly at night consuming mainly fish, invertebrates and terrestrial organisms that are washed into the water.  As a night feeder, the American Eel spends their days in deep pools near logs, boulders or other cover. Eels are carnivores and seek living prey rather than dead organic matter for food.

The spawning life cycle of the American Eel is common to this species. Eels spawn in saltwater and mature in freshwater. The cycle starts with the female maturing in freshwater streams over 5 to 20 years. Upon maturity they migrate downstream to the sea in autumn. Females are joined by the males, which have stayed in the estuaries, never growing much more than 2 feet long. 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 an area 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. Eel eggs have never been sampled in the ocean, but it has been estimated a single female may produce 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, called leptocephalus larvae, move by ocean currents. Upon reaching the coast, these larvae metamorphose into 2 l/2-inch long worm-like transparent "glass eels" and start climbing coastal streams to their eventual home to mature.

Fishing for eel is unimportant in Iowa, and most caught are taken incidental to other species. The eel's flesh, 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 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. 

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)).

Sources:

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.