The American Eel (Anguilla rostrata) is a unique migratory fish that is born in the Sargasso Sea in the Atlantic Ocean and enters estuaries along the east coast of North America. These tiny, transparent “glass eels” endure this long migrational journey by hitching a ride on the Gulf Stream, and peeling off into estuarine rivers and tributaries, including the Hudson River. Upon arrival, the eels begin to gain pigment to camouflage with the estuary environment, and at this stage, the eels are referred to as “elvers”. The American eel will then spend the majority of their adult lives in fresh to brackish (a mix of fresh and salty) water ecosystems until they are ready to undergo the long migration back to the Sargasso Sea to spawn.

Glass Eels. Photo Courtesy of the NYS DEC.

Due to their complex migrational patterns, a comprehensive understanding of the American eel population is greatly unknown. Some studies have indicated that the American eel is in decline over much of the eastern coast of North America. Glass eel monitoring will help to provide baseline information about their populations, which is crucial for management decisions. Eel mops in particular are a great way to monitor the presence or absence of glass eels in the Hudson River system. This data is critical to understand the migrational timing of glass eels at different points of the river.

Eel Mop. Photo Courtesy of the NYS DEC.


  • Attend a training to understand the life history of American eels
  • Help with the creation of eel mops
  • Count, measure, and identify the life stages of American eels caught in the eel mop

WHEN: 2020 To be determined, (typically March – Early to Mid May)

WHERE: Piermont Pier

WHO: Everyone! Children under the age of 18 must be accompanied by an adult

GET INVOLVED: To attend trainings & participate, contact: Laurel Zaima, Education & Oureach Coordinator,

This project is coordinate by the Department of Environmental Conservation (NYS DEC) Hudson River Estuary Program and the Hudson River National Estuarine Research Reserve