Anguilla rostrata, also known as the common or freshwater eel, can be found in a variety of habitats across an extensive geographic range. It probably has the broadest diversity of habitats of any fish species in the world. The American eel occurs in freshwater rivers and lakes, estuaries, coastal areas and open ocean from the southern tip of Greenland, along the Atlantic coast of North America, throughout the Gulf of Mexico and the Caribbean, to Venezuela, and inland in the St. Lawrence Seaway and the Great Lakes. The eel is an abundant resident of all tributaries to the Chesapeake Bay in its yellow eel phase. Before reaching this life-history phase, which comprises most of its life, the eel has undergone several physical and geographical changes.
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.
American eels are landed most often by eelpots, although they are also caught by anglers on hook and line. In the Chesapeake Bay area, most are collected in pots and support an extensive fishery. A majority of these eels are exported to support a large demand for American eels (usually the juvenile eels which are also called “glass eels”) in both Europe and east Asia. The current status of stocks is not well understood. In 1981, the commercial catch was more than 700,000 pounds in both Maryland and Virginia. Since then, the catch has been declining, possibly due to over exploitation of the stock, or possibly due to market conditions. The average size eel may be decreasing as harvesting pressure increases. An Atlantic States Marine Fisheries Commission Fisheries Management Plan is being developed.
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