Wayfarers on the Neversink

CUDDEBACKVILLE, NY — The Nature Conservancy is currently engaged in a three-year study intended to determine the abundance, density and biomass of American eel in the Neversink, Bea-Moc and Oquaga Rivers. American eels are unique in that they are catatrodromous, meaning they are born in the ocean but live in freshwater rivers—five to 20 years or more—before returning to the ocean to spawn and die. The spawning area is the Sargasso Sea, an area about 2,000 miles wide in the center of the Atlantic Ocean.

The project, part of a larger migratory fish initiative, involved isolating 10 sites on the Neversink River, 25 meters by 8 meters, using seine nets. All fish were identified, measured and weighed to provide an estimate of biomass (weight of fish species per square meter). Eels greater than 300 mm in length were separated out from the sample, measured, weighed, anesthetized and tagged with a Passive Integrated Transponder (PIT) tag. The tag identifies individual animals and allows them to be tracked over time. The hypothesis is that these larger eels are getting ready for their long spawning journey to the Sargasso Sea.

This fall, eels that have started their spawning run will be caught in stone weirs owned by the conservancy, allowing researchers to scan the tags of any previously tagged eels and measure and tag any others. This will help them understand what size eels, and what proportion of the river’s population, are leaving each year to spawn.