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American Eel Tracking Project on Aspetuck River Could Benefit Unique Migratory Species

The project is a collaboration between Aquarion Water Company, The Nature Conservancy, Sacred Heart University, the U.S. Geological Survey’s Silvio O. Conte Anadromous Fish Laboratory, and the Connecticut Department of Energy and Environmental Protection.

EASTON, CT | December 10, 2012

— For some, the idea of a silvery, two-foot long eel slicing through night-darkened waters while beaming a radio signal might seem best-suited for a science-fiction movie. For the partners in a project to tag and track American eels in the Aspetuck River, it’s an important idea that’s become a welcome reality.

This fall, Aquarion Water Company, The Nature Conservancy, Sacred Heart University, the U.S. Geological Survey’s Silvio O. Conte Anadromous Fish Laboratory in Turner’s Falls, Mass., and the Connecticut Department of Energy and Environmental Protection (DEEP) have collaborated to release and monitor 30 radio-transmitter-tagged eels into the Aspetuck River in Easton.

The three releases, which included 10 eels each, were scheduled to coincide with significant rain events to spur the eels’ migrations, encouraging them to move downstream to salt water where they spawn.

Tracking of the eels ended during the first week of December. A key goal is to gain valuable insight into how American eels—which have been proposed for federal endangered species listing—respond to river barriers and water diversions that create serious and sometimes fatal obstacles to the migrations that are crucial for the species’ survival. The partners anticipate continuing the tracking project next year.

“We’re proud of the strong partnership between The Nature Conservancy and Aquarion Water Company that has made this happen,” said John Herlihy Aquarion’s director of water quality and environmental management. “The broader collaboration between a prestigious environmental organization, a water company, a university and federal and state agencies is a terrific example of what can happen when diverse organizations pull together around shared ideas and goals.”

As adults, American eels migrate downstream from their freshwater homes to the Sargasso Sea to spawn. The adults don’t return, but in the spring, juvenile eels will head for rivers like the Aspetuck to mature. They may remain in freshwater systems for thirty or forty years before their biological clock indicates it’s time to spawn and they head back out to the Sargasso Sea.

“The problem for eels is they can have trouble finding safe passage downstream to salt water, especially in river systems with hydroelectric facilities or other diversions such as drinking water-supply systems,” said Sally Harold, The Nature Conservancy’s Connecticut director of migratory fish projects. “Through this incredible partnership, we hope to learn much more about how eels respond to weather events, temperature and light so that we can develop strategies to direct the eel to safe downstream passage.”

The eel-tracking project is part of a multiyear collaboration between Aquarion and The Nature Conservancy. American eels that move into Aquarion’s Hemlock Reservoir—one of three interconnected Aquarion public water supply reservoirs in the Easton area—are at risk of perishing in the water plant there. Knowing eels avoid light, Aquarion and the Conservancy partnered in 2009 to install solar- and wind-powered lamps to route the eels away from the reservoir and toward a safer path.

The eel-tracking work that was started this year will provide valuable information about how eels are responding to underwater lights, river flows and conduit closures, such as between the Aspetuck and Hemlock reservoirs.

In addition to allowing the eels to be released and tracked from the company’s land, Aquarion paid for the surgically-implanted radio transmitters upon which the project relies. The company also agreed to shut its intake pipe to the Hemlock Reservoir for three days following each release to allow a better understanding of the lights’ effectiveness and behavior of the eel during “gate closed” conditions.

“This tracking study also will help Aquarion measure and document the extent of our success in enabling the eels to move downriver,” said Aquarion’s Herlihy. “We need to know where we’re being effective and not effective in order to make the best possible decisions about additional investment to address these challenges.”

The eel-tracking project also relies on the expertise of Silvio O. Conte Anadromous Fish Laboratory, the Connecticut DEEP and Sacred Heart University.

The Conte lab loaned radio receivers for the project, and research ecologist Alex Haro has handled the delicate process of surgically fitting the eels with transmitters. The DEEP and supervising fisheries biologist Steve Gephard assisted in developing the project and planning for the green energy and lights installed in 2009. The agency has also helped with continued monitoring and project improvement.

Sacred Heart University graduate student Joe Cassone oversaw the transport of eels from Turner’s Falls and their releases into the Aspetuck River. Cassone has been responsible for maintaining the radio receivers and managing the data they generate. He also has conducted tracking of the eels with a handheld receiver from the edge of the river and around the reservoir.

“Joe is working on this project as part of his Professional Science Master’s (PSM) degree” said Jennifer Mattei, director of the PSM program. “We will be analyzing the data and writing a report to the group on how many eels have made it out of the river under these new conditions. We have already had some success, and our techniques along the Aspetuck will be applicable for other rivers not only in Connecticut but all along the East Coast.”

Aquarion Water Company is the public water supply company for more than 625,000 people in 47 cities and towns throughout Connecticut, as well as serving customers in Massachusetts and New Hampshire. It is the largest investor-owned water utility in New England and among the seven largest in the U.S. Based in Bridgeport, Conn.; it has been in the public water supply business since 1857. Across its operations, Aquarion strives to act as a responsible steward of the environment and to assist the communities it serves in promoting sustainable practices. Learn more about Aquarion Water Company and its subsidiaries or visit it on Facebook.


The Nature Conservancy is a leading conservation organization working around the world to conserve the lands and waters on which all life depends. The Conservancy and its more than 1 million members have protected nearly 120 million acres worldwide. Visit The Nature Conservancy on the Web at

Contact information

Bruce T. Silverstone
Vice President, Corporate Communications
Aquarion Water Company

James Miller
Media Relations Manager
The Nature Conservancy in Connecticut

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