Eel Monitoring

The American eel (Anguilla rostrata) is a migratory fish that is born in the Atlantic Ocean and enters North American estuaries, including the Hudson River, as tiny, see-through “glass eels” each spring. Once they arrive, they gain pigment and become part of the ecosystem for years to come. The species is in decline over much of its range, and baseline studies of populations, like the Hudson River Eel Project, are crucial for management decisions. 

Each spring, teams of scientists, students, and volunteers collect glass eels using specialized nets and traps on Hudson River streams. The juvenile fish are then counted and released upstream, and other environmental data is recorded. At the end of each season the data is compiled and sent along to decision-makers.

Volunteer with us! Click the link below to email us, and include where you live so we can find a nearby site. 

The Projects

  • Fyke Nets: Specialized fyke nets are set in the mouths of tributaries for six to eight weeks each spring, catching the juvenile eels as they migrate upstream. Each net is checked once daily by two or more volunteers. Often, people sign up to check a net one or more specific days per week during the sampling season. It takes approximately an hour to sample each day. All gear and materials are provided, but personal transportation to the site is required. Volunteers should be willing to work outside under variable conditions, and work collaboratively within a team of students and volunteers.
  • Eel Mops: Eel mops are devices made to mimic juvenile eel habitat. They are passive traps that are set in the water and checked for living things as often or as little as needed. In addition to glass eels, we often find invertebrates and other small fish as well! Click here to learn How to Make an Eel Mop.
  • Eel Ladders: On their journey upstream, eels are confronted by barriers that prevent access to favorable habitats. At a few locations by dams, we set eel ladders that catch eels attempting to swim upstream. The eels are then counted, sized, and released above the dam. The ladders are checked twice a week during the summer sampling season.

Sample Sites Include:

  • Richmond Creek in Staten Island
  • Saw Mill River and the Center for the Urban River at Beczak in Yonkers
  • Blind Brook in Rye
  • Furnace Brook in Cortlandt
  • Minisceongo Creek in West Haverstraw
  • Quassaick Creek in Newburgh
  • Hunters Brook in Wappingers Falls
  • Fall Kill in Poughkeepsie
  • Crum Elbow Creek in Hyde Park
  • Enderkill in Staatsburg
  • Black Creek in Esopus
  • Saw Kill in Annandale-on-Hudson
  • Hannacroix Creek in New Baltimore

Eel Project History

The Hudson River Eel Project began in 2008 with two sites, but has expanded over the years to engage roughly 1,000 volunteers each year in eel research. Over its lifetime, the Eel Project has caught, counted, and released over one million glass eels, helping these animals access better habitat.  

Over the course of the project we have collected some noteworthy data. In 2020, there was an average of over 1,000 glass eels per day in the fyke nets. This is a significant increase from the first few years of the project during which the average catch per day was around 20-30 eels. 

Eels and Education

Eels are great for outreach, education, and engagement! The Eel Project directly involves students and volunteers with scientific design and field methodology. Participants experience their local ecosystem firsthand and collect important information and relevant data about migrating fish. We also do classroom visits about eels and the project to schools that participate, about 2,000 people annually learn about their local environment through these programs.