Migrating Eels

On the Mianus River, in Greenwich, people are working not only to help alewives swim upstream to spawn, but to help eels get downstream the Long Island Sound and then the Atlantic Ocean to spawn (American eels are catadromous, the opposite of anadromous alewives, shad, etc.) But what could the Greenwich Time reporter possibly mean when he writes this:

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.

At first I thought he was saying the only freshwater eels were in the Mianus. But more likely he means American eels are the only freshwater eels in the Western Hemisphere. In any case, here's more about the eel situation:

A net hanging over the dam serves as a ladder that baby, or "glass," eels use to climb back into the freshwater. The eels remain for about 10 years in the Mianus Pond, then head out of the Long Island Sound to the Atlantic Ocean once they're mature enough to spawn.

Threatened by overfishing, hydropower plants, dams and other obstructions, the American eel recently came under consideration 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 Connecticut Department of Environmental Protection's Inland Fisheries Division. "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.