The Hudson River Eel Project, which has captured, counted, and released approximately 2 million juvenile eels since its inception in 2008, is a collaboration between high schools, universities, and adults who donate their time and effort along the Hudson River each spring. Its success was achieved thanks to a cadre of approximately 1,000 citizen scientists. river.
This year, for the first time, citizen science data from the project will be included as official input into the Atlantic Marine Fisheries Commission’s (ASMFC) peer-reviewed eel stock assessment report.
Because eels are an important part of the Hudson River system’s food web, this data helps government agencies make conservation management decisions. Young eels are important prey, but older eels become apex predators that maintain the balance of the ecosystem.
The project has set up about a dozen monitoring sites between Troy, New York, and New York City, specifically tracking the number of transparent “glass eels,” which are juvenile American eels. As eels migrate from the ocean to the Hudson River from February to May each year, tributaries and estuaries become bottlenecks for young fish, and capturing and counting them can provide insight into larger population trends.
“When done correctly, citizen science can be very useful because it can greatly expand not only the geographic reach of government agencies and biologists, but also the temporal reach.” [spread over time] said project leader Chris Bowser, education coordinator for the New York State Water Resources Institute, Cornell University College of Agriculture and Life Sciences, and the New York State Department of Environmental Conservation (NYS DEC).
ASMFC’s acceptance of the data last August was also due to the Eel Project’s strong data quality control procedures. The procedure was developed in consultation with NYS DEC partners and Cornell University researchers to ensure the protocol was simple, standardized, and reproducible year after year. Citizen scientists are well trained and have their numbers and procedures checked.
“We have tried to collect data as robust as what is being done at the agency level in other states,” Bowser said.
The American eel is a migratory fish that hatches in the saltwater of the Sargasso Sea and migrates as willow-leaf-like larvae to freshwater in the Caribbean islands, South America, the Gulf of Mexico, and the East Coast from Florida to Canada. Once they reach the brackish waters of coastal estuaries, they transform into translucent 2-inch juvenile glass eels. When they move into muddy freshwater streams and streams, they develop pigment and develop into small adults called “elvers.”
The next adult stage is a sexually immature “yellow eel” that appears brown, dark green, gray, or mustard yellow. They remain as yellow eels for 5 to 30 years until they reach sexual maturity, then return to the Sargasso Sea as “silver eels” to spawn and possibly die.
Along the 150-mile-long Hudson River watershed, eels invade every waterway that connects to the Hudson River, including urban rivers like the Sawmill River in Yonkers, Fallkill Creek in Poughkeepsie, and Postenkill Creek in Troy. It also invades rural areas such as Hickory Creek in New Baltimore and Black Creek in Ulster County.
“The wide geographic diversity of eels means that the socio-economic diversity of volunteers is also wide-ranging,” Bowser said.
For example, monitoring at the Fall Kill Creek site in Poughkeepsie began in late February.
“We have a team of volunteers there, along with educators and interns, every weekday at 4 p.m.,” Bowser said. He said it’s a common sight for high school students to wade into 2-foot-deep water around the net. Twelve-foot-tall nets are constantly placed along the shoreline where glass eels migrate. Another group may be carefully counting and weighing the eels, while others are collecting water temperature and air temperature data.
Overfishing, pollutants, habitat loss, climate change, and obstacles such as dams are all taking a toll on eels.
“Every dam is a small speed bump along the eel migration route,” Bowser said. As a result, glass eels, once counted, are released beyond at least the first migration barrier, such as a culvert, road, or dam, according to a protocol based on ASMFC requirements.
“What I love about the Eel Project is that the volunteers actually become scientists and take a step deeper into thinking about research methods and the research questions we are trying to answer.” said Bowser.
The Hudson River Eel Project is supported by the Hudson River Estuary Program and the Hudson River National Estuarine Research Reserve, along with NYS DEC and Cornell University.
