The American Eel: A Fascinating Fish
When you hear the word eel, what comes to mind? For many, eels are repulsive, slimy creatures to be avoided. But to fishermen and crabbers, eels are an important commodity, either as bait or as a delicacy for export. Whatever you may think of them, eels are extraordinary fish.
For such lowly creatures, myth and mystery used to surround this fish. Tribes in the Philippines once thought that eels were the souls of the dead. Some Europeans believed that skin rubbed with eel oil caused one to see Fairies. Because no one had ever seen a female eel with eggs, the Greeks once believed that baby eels were produced by spontaneous generation. This last myth was dispelled in 1922 when a scientist, Johannes Schmidt, discovered the spawning ground for both American and European eels in the Sargasso Sea, near Bermuda.
This discovery led to a greater understanding of the fascinating life cycle of eels. The American eel (Anguilla rostrata) is the only catadromous fish found in the Chesapeake Bay, meaning that it lives most of its life in fresh and estuarine water, and migrates into saltwater to spawn. Very few fish matches the eel’s ability to exist in such a broad diversity of habitats.
Prior to their fall migration, adult eels undergo changes that adapt them for life in the ocean. These changes include an accumulation of fat and degeneration of the gut. Spawning migration takes place between August and December, with eels being most active during the night. American eels spawn in the western Sargasso Sea between January and March. A female eel may lay between 400,000 and 2,500,000 eggs. Parent eels die after spawning.
The eggs hatch and the young, which look like transparent ribbons, are seized by ocean currents and transported to the mouth of the Chesapeake Bay and other inlets of the Atlantic Ocean. This journey can take months or even years. After their first year, the young change, taking on the form of tiny, unpigmented eels, known as glass eels.
As glass eels move into coastal areas they become pigmented. The body is now dark brown and they are now known as elvers. The elvers continue the journey, wriggling upstream into brackish and freshwater streams, rivers and creeks. Elvers are found in the Chesapeake Bay in April and May.
When elvers stop migrating they undergo a period of growth and are known as yellow eels, remaining in the Bay and its tributaries from eight to twenty-four years. While in estuaries and rivers, eels have small home ranges in which they feed. Yellow eels may migrate into estuaries during the spring, move into rivers in summer and autumn and hibernate in the mud during the winter. They are more active at night, and feed voraciously on a variety of fish, insects, crayfish and worms.
About one year before reaching sexual maturity, the eel undergoes its last transformation before spawning, resulting in the silver eel phase.
Although considered a hardy fish, the status of the eel in the Chesapeake Bay is not clear. There are two eel industries; a bait market for crab trotliners and a live eel market for human consumption. It is hard to determine how much the bait fishery affects the eel population since the number of eels harvested for crab bait has not always been reported.
Some countries raise eels in order to meet the demand for meat. Eel meat can be fried, jellied, stewed or smoked.
In addition to these two industries, other factors can affect the eel population. Because of their bottom-feeding behavior, contaminants in bottom sediments and low dissolved oxygen levels can negatively impact eels. Probably the biggest threat eels face is the blockage of important habitats by dams and other obstructions.
Efforts to remove blockages from important fishery habitats are occurring throughout the watershed. Where removal is not possible, different techniques are used to help fish migrate. These include fish elevators, fish ladders or partial removal of the blockage. By ensuring safe fish passage, reducing pollutants and monitoring populations, eels and many other valuable fish will continue to flourish in the Chesapeake Bay.