GREENWICH, Conn. -- Michael Aurelia raised a dripping net of a baby alewives from a pool of the Mianus River Dam's fishway, examined them, and then dumped the silver fish back in the water and pulled out a partially submerged crate.
Each month, Aurelia resets an electronic counter in the crate to track how many of the alewives swim in from Long Island Sound to spawn. But that was not why he was at the dam this sunny morning. He was looking for baby American eels.
"You can see how fast they move," Aurelia, former director of the Inland Wetlands and Watercourses Agency, said as he spotted a 2-inch baby eel wriggling in the crate. "Sometimes they get stuck in here. There's probably thousands of them in the water."
The Mianus River Dam, where alewives reach freshwater each April, also plays a crucial role in the lives of the Western hemisphere's only freshwater eels. A net hanging over the dam serves as a ladder that baby, or "glass," eels use to climb back into the fresh water. The eels remain for about 10 years in Mianus Pond and then head out of Long Island Sound to the Atlantic Ocean when they are mature enough to spawn.
Threatened by overfishing, hydropower plants, dams, and other obstructions, the American eel was recently considered by the federal Fish and Wildlife Service for endangered species status.
"We're seeing fewer in Connecticut and throughout the entire (Northeast) range," said Rick Jacobson, assistant director of the Inland Fisheries Division of Connecticut's Department of Environmental Protection. "The concern is manmade dams and other barriers to fish passage, both in terms of moving upstream and downstream. Because of their migratory pathways, they frequently go through turbines or filter systems into water supply reservoirs. That, and overall degradation of habitat."
Nets are a primary way that conservation officials help eels circumnavigate barriers such as dams.
The Mianus River Dam net, damaged by April's tax day floods, no longer reaches the estuary at low tide and is in need of repair, Aurelia said.
American eels start as eggs hatched in the Sargasso Sea, a 2-million-square-mile warm-water body in the North Atlantic between the West Indies and the Azores. They can take years to reach freshwater streams, where they remain until mature. Then they return to their Sargasso Sea waters to spawn and die. Females can lay up to 4 million eggs per year and frequently die after egg laying. Eels can exceed 2 feet in length and can weigh up to 9 pounds.
Eels have been a part of the human diet for centuries, conservationists say, and glass eels have been illegally harvested in the United States and sold on the Asian market since at least the 1970s.
Federal officials undertook a study of American eels in 2004. They found that while the eel population has declined in some areas, the species' overall population is not in danger of extinction for the foreseeable future.
Denise Savageau, Greenwich's conservation director, said she, Aurelia, and state Department of Environmental Protection officials who serve as stewards of the dam's fishway, view the eel pass as an essential part of the area.
"We do pay attention to eels. We think it's important for people in Greenwich to understand that a lot of things live in these waterways," Savageau said. "People always talk about the Long Island Sound being so important. It is, but this really is an essential estuary."