Eels

Eels

Wolf eel, © Amadeo Bachar

At a glance

Eco-rating Mercury Omega-3s
+-Freshwater eel
Worst
Unknown

More about Freshwater eel

Freshwater eels, like other eels, have long, snakelike bodies.

Eels from the Anguilla family develop in three distinct stages: from glass eel, to yellow eel, to silver eel. Larvae turn into glass eels that lack coloration. During this stage, eels move from the ocean to coastal estuaries.

As the eels gain pigmentation and become yellow eels, they move to freshwater. Finally, these eels metamorphose into silver eels, when they are able to reproduce. The eels return to the ocean to spawn where they die soon after.

Commercial Sources

The main sources of freshwater eels for unagi are China (which dominates the U.S. market), Japan, Taiwan, Vietnam (which dominates the Asia/Japan market).

Unagi was traditionally prepared from Japanese eel, but because of declining stocks, most unagi today consists of European eel and to a lesser extent American eel.

Capture Methods

Most freshwater eels come from fish farms. A wide variety of techniques are used: recirculating tanks, modified wetland polyculture, outdoor still-water ponds, greenhouse systems plus sedimentation ponds, outdoor flow-through ponds, basic greenhouse systems and open net pens.

+-American eel
Unrated
Moderate

More about American eel

The American eel, like other eels, has a long, snakelike body. It lives in freshwater, preferring flowing streams, but migrates to the Sargasso Sea in autumn to spawn. American eels average 1.5 feet (46 cm) in length, but they can reach up to 5 feet (152 cm).

Commercial Sources

American eels are found in the freshwater and marine environments of eastern America, from western Greenland and Labrador to Central and northern South America, including the Bahamas and the Greater Antilles.

The main sources of American eels are Canada and the United States.

Capture Methods

American eels come from coastal fisheries, not fish farms. They are primarily caught with pots and traps.

+-American conger eel
Unrated
Elevated

More about American conger eel

The American conger eel, like other eels, has a distinctive long, snakelike body. These eels live in shallow inshore waters and are often caught by American anglers along piers, docks and jetties in middle Atlantic states. Nocturnal predators, American conger eels feed on fish, crustaceans and small mollusks, and can grow up to 7.5 feet (2.3 meters).

Commercial Sources

American conger eels are found in the western North Atlantic, from Cape Cod in Massachusetts to northeastern Florida, including the northern Gulf of Mexico.

The main source of American conger eels is the United States.

Capture Methods

American conger eels come from marine fisheries, not fish farms. They are primarily caught with bottom trawls, pots and traps. Additional types of fishing gear include gillnets and hooks-and-lines.

+-European eel
Unrated
Elevated

More about European eel

The European eel, like other eels, has a distinctive long, snakelike body. Young eels live in freshwater under stones, in mud or crevices but move to deep-sea waters when they reach sexual maturity. European eels have been introduced to coastal waters around the world, and they can reach 4.5 feet (1.5 meters).

Commercial Sources

European eels are native to the freshwater and marine environments of the eastern North Atlantic, including the Baltic and Mediterranean Seas. However, they have been introduced into Brazil, Iran, Israel, Japan and the United States.

The main sources of farmed European eels are Italy, the Netherlands and Denmark. However, small amounts of wild eels are caught all around Europe.

Capture Methods

Most European eels come from fish farms. Wild eels are primarily caught with pots and traps. Additional types of fishing gear include hooks-and-lines, seines, gillnets and spears.

+-European conger eel
Unrated
Elevated

More about European conger eel

The European conger eel, like other eels, has a long, snakelike body. Young eels inhabit coastal waters and at adulthood move to deeper waters. Nocturnal predators, European conger eels feed on fish, crustaceans and mollusks. The record length for a European conger eel is 9 feet (2.7 meters) in length.

Commercial Sources

European conger eels are found in the eastern Atlantic, from Norway and Iceland to Senegal, including the Mediterranean and Black Seas.

The main sources of European conger eels are Spain and France.

Capture Methods

European conger eels come from marine fisheries, not fish farms. They are primarily caught with hooks-and-lines. Additional types of fishing gear include bottom trawls.

+-Japanese eel
Unrated
Unknown

More about Japanese eel

The Japanese eel is native to southeast Asia, where it is commonly farmed. These eels can grow to be 5 feet (1.5 meters) long and weigh up to 2 pounds. Wild eels are catadromous, meaning that they live in freshwater but travel to the ocean in order to breed.

Commercial Sources

Japanese eel aquaculture is common in China, Vietnam, South Korea, Taiwan and other southeast Asian nations.

Capture Methods

Japanese eels come primarily from fish farms. Little information is available on types of systems used to raise eels.

Recommended servings per month

Contaminant Men Women Kids 6-12 Kids 0-5
American eel Mercury, *PCBs 4+ 4+ 3 2
European eel Mercury, *PCBs 3 4+ 2 1
Japanese eel Unknown 4+ 4+ 4+ 4+
Freshwater eel Unknown 4 4 4 4
American conger eel Mercury 3 4 2 1
European conger eel Mercury 3 4 2 1

* This fish has been shown to have elevated PCB levels in some places. Please visit the EPA’s National Listing of Fish Advisories to check for any consumption alerts in your area.

Eco details: 
  • Many eel species live in coastal and estuarine areas, where they may be exposed to water pollution caused by runoff and coastal development.
  • Little is known about the environmental impacts associated with farming eels. However, eels are carnivorous, and raising one ton of eels requires roughly four tons of wild fish used as feed.