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The life history of the American eel is complex and not fully understood. It is a catadromous species, which spends most of its life in rivers, lakes and estuaries, but migrates to the ocean to spawn.
The eel begins and ends its life in the waters of the Sargasso Sea, an area north of the Bahamas.
The leptocephalus, a pelagic larvae of less than two inches in length, drifts with the ocean currents for 9 to12 months before entering coastal waters.
When it reaches approximately 2.4 inches in length, the leptocephalus metamorphoses into a transparent, "glass" eel.
In autumn the glass eels migrate into estuaries along the Atlantic coast, including Chesapeake Bay, where they become pigmented. These eels are known as elvers.
Some elvers remain in the estuaries, but others migrate varying distances upstream, often for several hundred kilometers, overcoming seemingly impassible obstacles such as spillways, dams, falls and rapids.
Now in their yellow eel phase, the American eels will remain in the brackish and fresh waters of these rivers for the majority of their lives–for at least five and possibly as many as twenty years.
The yellow eels are uniformly greenish-brown to yellowish-brown dorsally, and whitish-gray ventrally. Females reach a maximum length of five feet, and males grow as long as two feet.
These residents of the Chesapeake Bay and its tributaries are nocturnally active omnivores, feeding on insects, mollusks, crustaceans, worms and other fish.
Before beginning its life-ending migration back to the waters of the Sargasso Sea to spawn, the eel must undergo further profound physical changes. Just prior to the reproductive migration, the eel stops feeding, the eyes and pectoral fins enlarge, the visual pigments change and the body color pattern transforms. The sexually mature eel has a gray back, pure white belly, and a silvery bronze sheen on its flanks. The migration occurs throughout autumn nights with adults descending streams and rivers, swimming through deep grass and shallow ditches, for a January spawning in the warm Caribbean waters.
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