When deciding to attend graduate school, I must admit that the American eel was not on the top of my list of fish to study. However, an opportunity to evaluate the impacts of hydroelectric dams on eel migration helped make the decision for me.
Seven years later, what I have learned about this unique and often misunderstood “snakelike” fish species has made me one of its biggest fans.
Historically, eels were abundant in estuaries and freshwater tributaries in much of the eastern U.S. and Canada. The construction of dams changed all this, drastically limiting eel migration routes from the ocean to upstream freshwater areas.
As a fisheries biologist, I continually look at the impacts that a species’ decline has on an entire ecosystem. In the case of the American eel, the population decline has an important – and fascinating – connection to certain native freshwater mussel species. Larval mussels need to attach to the gills of a fish in order to complete their life cycle. Some mussel species specifically need American eels to survive.
With fewer eels headed upstream, mussel larvae have fewer hosts to help them survive. In rivers where dams have excluded eels for decades or longer, some freshwater mussel populations have also declined. Fewer mussels means poorer water quality because mussels have the ability to filter gallons of water a day.
Working on the restoration program for American eels on the Susquehanna River is never dull and continues to bring daily adventures. Along with several partner agencies, my colleagues and I have been trapping young migrating eels at the Conowingo Dam and stocking them into the upper watershed for several years. In 2013, we collected nearly 300,000 elvers (baby eels) for the restoration program.
Stocking eels has been very successful in the Susquehanna River. And to our delight, we are now finding eels with larval mussels attached to the gills, which will promote the growth of the mussel population.
Watch American eels swim upriver
For me, it has been very rewarding to be part of this successful restoration program. I am proud to share the story of the American eel – an underappreciated resident of much of our freshwater streams with an amazing life cycle and connection to our environment.
For more information on the Susquehanna River American eel stocking program, read more at: http://www.fws.gov/northeast/marylandfisheries/projects/Eel%20passage.html.