There’s something wriggling in the Hudson River, and it’s a sign of rebirth for the waterway’s once-vibrant ecosystem.
Experts say glass eels, which have long been endangered, are making a “bumpy comeback” in the Hudson after decades of population decline.
The snake-like sea creatures have transparent skin and are easy to miss, but they’re key to the health of the Hudson, which has been battered by pollution over the last century. They provide a rich protein source for striped bass and bald eagles along the waterway, especially during the late winter when there isn’t much to hunt.
Their presence in the Hudson also helps keep it clean. The eels transport mussel eggs in their gills that eventually hatch in the river and filter pollutants from the water once they grow. If the eels disappear, so could the bivalves.
Conservationists have raised concerns about the declining glass eel population since at least the 1970s. While the eels’ population in the Atlantic Ocean remains at a historic low, there is new hope for their comeback in New York’s largest river, according to experts.
In 2023, the state Department of Environmental Conservation caught and counted 250,000 of the eels, which measure 2 to 3 inches. That’s 25 times more than were counted in 2008, the first year the department began surveying the slippery fish.
Scientists say they aren’t sure what’s causing the trend. “It’s not a clear rise,” said Chris Bowser, the coordinator of the DEC’s Hudson Eel Project. “It’s a bumpy rise, but we’re still seeing quite a few glass eels coming in, and my hope is that is a sign that maybe eel numbers are starting to rise back up.”
Along the Fall Kill Creek, which flows out of the Hudson River in Poughkeepsie, around 80 miles north of New York City, Bowser and a team of citizen scientists catch piles of eels in traps that look like camping tents tipped over in the water. The group, which is mostly made up of teenagers, counts the number of juvenile glass eels that have made their way into the trap every weekday. It’s rarely empty.
High school students assisted state experts with a recent eel count in Poughkeepsie.
Chris Bowser/NYSDEC
The eels are a sight to behold. When held up close, researchers can see their small red beating hearts and black spines through their skin. The eels are born neither female nor male; environmental factors determine their sex.
“If you see an eel up close, they are one of the most amazing, mysterious creatures that lives in the sea,” said George Jackman, habitat restoration manager at the advocacy group Riverkeeper. “They are the ultimate New Yorker because they are ambisexual.”
The eels’ journey to New York is treacherous. Those studied by Bowser’s team were among billions that hatched nearly 1,000 miles away in the Sargasso Sea, in the middle of the Atlantic Ocean.
Experts say there are many biological unknowns about the fish, making it difficult to manage their populations. Their precise breeding location in the ocean remains a mystery.
Despite the promising local numbers, the eels are still in danger. Bowser said the current population is far less than 10% of what it was before the 1970s, when glass eels were considered a common sight. Now, eels are threatened at each stage of their life cycle.
“Everything is impacting them,” said Mari-Beth DeLucia, director of land protection for the Nature Conservancy, an environmental organization. “It’s death by a thousand cuts.”
Once they grow, the eels return to the Atlantic Ocean and head south to mate in the Sargasso Sea.
Chris Bowser/NYSDEC
The warming and acidification of oceans due to climate change slows down or even stops currents, meaning the eel larvae that hitch a ride on ocean waves have a harder time making it to freshwater.
“If you’re just a little willow leaf [eel larvae] and the Gulf Stream slows down or speeds up, that could really impact your ability to get to the coast, especially when you can’t swim,” DeLucia said.
When the eels make it to the Hudson River, manmade structures like dams and hydroelectric plants prevent them from migrating upstream. Overfishing in the Atlantic also affects the river’s eel population.
Glass eels can fetch as much as $2,000 per pound on the market despite U.S. fishing restrictions and the European Union’s bans. The baby eels are sold as seed stock to foreign businesses that raise them to maturity for food, such as sushi. Even when farm-raised, eels harvested for human food depend on endangered wild populations.
The Atlantic States Marine Fisheries Commission is slated this month to vote on new fishing quotas, which will either further restrict the number of eels allowed to be harvested or extend the current quota three more years.