"Estuaries such as Long Island Sound are among the most valuable ecosystems in the world. The Sound supports diverse marine life, including most of the fish and shellfish we value as food ..."

– Connecticut Sea Grant

Conservation & Research

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Long Island Sound Fun Fact

Long Island Sound is 113 miles long, 21 miles wide (at its widest) and holds about 18 trillion gallons of water. Its average depth is 63 feet – which is just a little deeper than the height of our IMAX screen! Can you fathom that?!

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Common Name: American eel

Latin Name: Anguilla rostrata

Size/weight:  Females average 2 to 3 feet but may grow to 5 to 6 feet long. Males are generally half as big.

Range: American eels range from Greenland to South America, occurring in all major streams along the Atlantic coastline. The females migrate far inland, and have been documented in nearly all states east of the Rocky Mountains. This is possible because eels are able to live out of water for short periods of time. Their ability to slither up a moist slope allows them to circumnavigate major obstructions (e.g. dams and waterfalls) along their routes.

Habitat: Varies by life stage. See “Description” below.

Diet:  insects, smaller fish, fish eggs, crustaceans, worms, frogs.

Predators:  At sea: fish, birds. In inland waters: fish, turtles, birds, raccoons.

Description:  This is a fish – and eels are fish, by the way – that lives a life of several amazing metamorphisms that take it from sea water to fresh water and then back out to the salty ocean again. (That’s something few fish can do.)

An eel’s life stages are:


• “leaf fish” – These larvae look sort of like a clear flat willow leaf. Hatching in the Atlantic’s Sargasso Sea (SE of Bermuda), they ride the Gulf Stream currents for about a year.


• “glass eel” – Nearing the East Coast, leaf fish morph into the familiar eel shape. Tiny glass eels are still transparent but can now actively swim toward land.


• “elver” – Entering estuaries, they take on a brownish pigment.


• “yellow eel” – As elvers feed and grow, they turn olive-green with a yellow underside. They’ll stay in this adult stage for 5 to 20 years. Females swim upstream into fresh water and may even wriggle across land to ponds and lakes. Males tend to stay in more brackish waters.


• “silver eel” – In the fall, yellow eels that are ready to reproduce will stop eating, take on a silvery hue and their digestive systems shrink away to make room for new reproductive organs. Fueled only by their fat reserves, they swim back out to the Sargasso Sea to mate, lay eggs and die.


Conservation Note: Eel “landings” peaked in the late 1970s and early 1980s when record quantities of eels were caught and shipped to Asia, where folks have a taste for juvenile eels called elvers. But we caught too many eels too quickly. The number of eels harvested since then has dropped dramatically.

According to estimates from the International Council for Exploration of the Seas (ICES), the “recruitment level” (that is, the baby eels produced each year) is only 1 percent of what it was before the 1980s. Populations may be at record-low levels. In 2000, the Atlantic States Marine Fisheries Commission (ASMFC) issued an eel management plan. As eel “landings” continued to decline, the commission approved further protections in 2004. The U.S. Fish & Wildlife Service is reviewing whether eels need protection as a threatened or endangered species.

Besides overfishing, eel issues identified by the ASMFC include:
• dams have blocked eels from their migrations up rivers and streams.
• climate change may raise sea levels, which could affect the Sargasso Sea, a huge area south of Bermuda that is the American eel’s only mating spot/hatchery.
• climate change also could alter the Gulf Stream, hindering the migration of glass eels toward land.
• pollutants collect in eels’ fat reserves. That’s bad news for both the eels and anyone who eats them.

Although it may be hard to rally public support around an animal that is slimy and snake-like, things are being done to help eels. It’s now illegal to ship eels into or out of Europe. In the U.S., recent changes in size regulations have eliminated the elvers fishery in all states except Maine and Florida. And in Connecticut, the U.S. Fish & Wildlife Service, the Nature Conservancy, municipal conservation groups and the Aquarion Water Co., which supplies water to 39 cities and towns, all have been working on ways to help eels get around dams.

See them in their own exhibit in the Rivers to the Sound watershed gallery.