New York Wildlife: Fish: Eels

Eels of New York

Lampreys are parasites with round sucker mouths and no scales or paired fins. They have no bones; only cartilage.

Eels are snake-like fish, with pointed heads and fish-like mouths. They have a pair of pectoral fins and a continuous dorsal/caudal/anal fin around the back half of their body. They have scales; very small ones.

Eel Life Cycle
Eels are catadromous, in that they spawn in the oceans, live out  some of their lives there, and then migrate to freshwater for a longer period of their lives until they are ready to spawn again. The eel's life cycle can be divided into seven stages. Eggs hatch into Leptocephalus eels, which are transparent, leaf-shaped larvae that drift on the upper surfaces of the open ocean for several years feeding on plankton.  Leptocephali develop into Glass eels and begin to take on the typical eel shape. They are still transparent (thus the name), but their internal organs are visible, and can reach lengths of 4 inches. Glass eels migrate to coastal areas and congregate in the brackish waters of estuaries in great numbers. Some Glass eels begin to migrate upstream; others remain in the estuaries. Eels are so versatile and adapted to this freshwater migration that they find their way into most bodies of fresh water in the world; even scaling waterfalls and traversing land to do so.

Through their journey up freshwater channels eels develop pigmentation and begin feeding on larger prey (crustaceans, worms and insects) in what is considered the Elver, or young eel stage. They begin to take on a yellow color as they reach 22 to 31 inches in length and are then known as Yellow eels. At this point they are considered to be sexually immature adults. Yellow eels will continue "running" upstream, crossing lakes and wetlands for up to 30 years, with some (females mostly) growing as large as 5 feet long. Those that remain in the estuary environment, continue through their life-cycle a lot more quickly than those that travel up freshwater. Those that do venture into freshwater tend to live longer and grow much larger.

When eels mature, they lose their yellow pigment and take on a dark grayish-brown color on top and silver underneath. Their eyes enlarge, their bodies thicken, and they discontinue feeding. Now referred to as Silver eels, they head back out to sea to spawn.

In Upstate NY we only have one species of Eel in our waters; the American Eel (Anguilla rostrata).
The details presented below generally represent the Glass, Elver, Yellow and Silver stages in the American Eel's life.

Click here for New York State sportfishing regulations

New York Fishing Guide Books

Inland Eels of New York:

American eel
Anguilla rostrata

Click images for enlargements.

Identifying characteristics: Glass eel stage:  transparent snake-like body, with pink gills and visible digestive tract. Pointed head. Pectoral fins present. Elver stage:  darker coloring (gray to greenish-brown); single gill slit in front of pectoral fins. Yellow eel stage: yellowish- brown tinted skin; single gill slit in front of pectoral fins; lower jaw protrudes beyond upper jaw. Silver eel stage:  grayish-brown skin on the back and silvery under parts;  single gill slit in front of pectoral fins; large eyes; robust body; lower jaw protrudes beyond upper jaw.

Size: Glass eel stage: up to 4 inches in length. Elver stage: up to 3 feet in length. Yellow eel stage: averaging 3 feet, with some specimens reaching 5 feet (usually females). Silver eel stage: Generally the same lengths as the Yellow eels, but weigh more.

New York State record: 7 lb. 14 oz. (7/25/84)

Habitat: Although many eels begin migrating up freshwater systems starting at the Glass eel stage, some remain in the ocean at the mouths of rivers (estuaries). Eels can survive in most marine and freshwater systems. Their body adapts from open ocean-dwelling to freshwater migration, to bottom-dwelling, and back to ocean migration.

General range: In NY they are found in virtually all freshwater systems, including the major rivers, Great Lakes, and the Finger Lakes. Eels in the Elver stage may be found in the Hudson River estuary. This particular species of eel is found in waters from Greenland to Brazil.

Food: Leptocephali feed on ocean plankton. Evers and Yellow eels are carnivores that feed on crustaceans, worms, smaller fish and fish eggs, amphibians and dead animal matter. At the Yellow stage feeding takes place at night. Silver eels have degenerated digestive tracts and do not feed.

Recommended baiting: Netting is often used to catch eels during their runs. Mature eels will generally take the same bait as other fish, with a preference to nightcrawlers strung near the bottom.

Predators: Larger predatory fish, humans (although not so much in this country)

Stocked? No; native.
Reproduction: Sometimes taking up to 40 years, Yellow eels begin to change into Silver eels, a transformation that prepares them for their long trek back to the ocean to spawn. They no longer feed and their digestive tracts begin to deteriorate. Their bodies grow more robust, storing large quantities of fat, and they develop thicker skin. Their dark coloring and silver underside make for more suitable ocean camouflage. Spawning occurs in the Sargasso Sea, where female Silver eels can lay up to 5 million floating eggs. Males fertilize the eggs and a massive cloud of spawn floats near the surface, providing food for lots of marine animals. Since the adults cannot feed, they are presumed to die shortly after spawning.

Nesting: no nesting habits observed.

Other Info.: American eels secrete a slimy mucous that coats their body during times of stress. This not only allows them to avoid being captured, but also helps them slither across land or other barriers during freshwater migration.

Although eels are considered delicacies in many areas in the world, the American eel lucks out: we don't have much of a taste for slimy, snake-like creatures. Unfortunately their porous skin, which helps them absorb oxygen, also makes them vulnerable to pollution. Man-made barriers and other obstacles to their freshwater migration cause problems for eels and well as humans.

Their tendency to squeeze into tight places and talent for exploring ways to get around obstacles lead to many eels getting trapped in the filters of turbines.

Eel-skin wallets, purses and other accessories, are not made from eels, but from Hagfish, which is more closely related to the lamprey than the eel.