When you think of eels, you probably think of the ocean. But did you know that West Virginia is a temporary home to many American eels?
The migration of those eels in relation to electric dams is the focus of a study under way by Stuart Welsh, an adjunct assistant professor in West Virginia Universitys Davis College of Agriculture, Forestry and Consumer Sciences. Along with graduate student Jennifer Lowery, the pair is looking at American eels in the states Shenandoah River.
American eels become temporary residents of West Virginia after swimming upstream from either the Gulf of Mexico (Mississippi River) or the Chesapeake Bay (Potomac River).
Some recent studies have supported population declines of the American eel, but current evidence does not support a single cause for the decline,Welsh said.The ecology of American eels is not well understood, in part, because of a complex life history that includes ocean, estuary and river habitats. Our research is focused on understanding the migration of the American eel in riversa habitat in which many American eels spend most of their lives, in some cases, over 20 years.
American eels begin life in the Sargasso Sea (North Atlantic Ocean) and undergo several changes throughout their life cycle. Young eels drift with ocean currents from the Sargasso Sea into areas over the continental shelf and near coastal estuaries (where rivers enter the ocean), and then the young eels change shape. They go from the leaf-like shape that they started out as to a transparent eel, also called a glass eel. As the eel ages, its skin becomes darker, and is then called an elver.
In the next phase of the cycle, eels transform intoyellow eelsand begin to feed on aquatic life, which may include crayfish and other small fish. Many yellow eels migrate upstream toward headwaters of rivers, and encounter obstacles along the way, such as dams.
Welshs research involves the monitoring of fishways, also called eel ladders, on dams.
Dams deter upstream movements of eels, but recently installed eel ladders on some dams in the lower Shenandoah River allow eelssafe passage to upstream waters,Welsh said.Initially, our research examined the number and size of eels using the ladder, and the timing and seasonal use of the ladder. So far, over 6,000 eels have used the ladder during spring, summer and fall months.
Lowery, of Gaithersburg, Md., began her graduate work in May. Her part of the project includes evaluating the eel ladders at the Millville Dam in West Virginia and the Warren Dam in Virginia. As the eels pass through the dam, Lowery takes pictures of them and then tags them in order to keep track of certain ones and check their ages. She also checks eels for the presence of a particular parasite that may be associated with eel population declines.
Ive always been interested in fisheries in general,Lowery said.Ive done some research on eels in the past and knew that they were interesting.
After reaching their headwater destinations, yellow eels continue to grow and develop into adulthood and change their color from a yellowish back and white underbelly to a darker bluish-silver back and white belly (and are then called silver eels).
Silver eels migrate downstream to the ocean, and additional research is planned to study these downstream movements. The Sargasso Sea is the final destination for the adult silver eel where it spawns and eventually dies, and then its larvae begin the next life cycle.
The journey of the American Eel is a complex and fascinating one,Welsh said.With this study, we hope to gain a better understanding of it.