Farmed oysters may help replenish New York’s dwindling wild populations

CORNELL UNIVERSITY MEDIA RELATIONS OFFICE

FOR RELEASE: June 17, 2026

Kaitlyn Serrao

607-882-1140

kms465@cornell.edu

Farmed oysters may help replenish New York’s dwindling wild populations

ITHACA, N.Y. – Farmed oysters are mixing with and potentially adding to populations of wild oysters – a once-abundant species in New York’s estuaries and rivers that has declined drastically over the last century.

A new study from Cornell University offers genetic evidence and the first documented proof that farmed eastern oysters are adding to and breeding with wild eastern oyster populations in the western and central Long Island Sound. 

“Oyster farms might provide ecosystem services to the natural system, with one of those being a boost to oyster populations that are dwindling,” said Matthew Hare, associate professor and senior author of the paper. “If a farm is near an oyster population and there’s any reproduction on the farm, it’s possible that it can provide a demographic supplement and basically build up populations nearby, because the offspring from the farm could end up in the wild population.”

In the 1600s, New York’s estuaries and rivers were home to some 220,000 acres of oyster reefs until overfishing, pollution and siltation led to their decline by the 1900s. In 2023, 84% of New York harvested eastern oysters were reared in oyster farms. 

Regulations require farmers to raise oysters in clean water, since oysters can be tainted by polluted waterways, and become harmful if eaten. As a result, regulatory agencies prohibit aquaculture in places with compromised water, mostly near urban areas, where sewage and runoff can contaminate waterways. For this reason, most of the Hudson River, the East River and the far western Long Island Sound are closed to oyster farming.

In the study, Hare and colleagues analyzed the genomes of native oyster samples collected from the Hudson River, the East River and the Long Island Sound in Connecticut. Hare had previously found and documented genetic markers that contain signatures of domestication.

Samples of wild populations from the Hudson River revealed genetic variation consistent with a single breeding population, meaning they had rarely mixed with farmed oysters, if at all, as predicted from the absence of oyster farms. “Whereas in the East River and in Connecticut, we saw oysters had this kind of mixed pattern, the mixture being the wild and also the farmed aquaculture ancestry,” Hare said. 

Though more study is needed to fully understand the long-term effects of bred, farmed oysters mixing their genes with wild oysters, some of the traits breeders have selected for in agricultural strains – such as disease resistance – may benefit wild populations.

The study was funded by New York Sea Grant.     

For additional information, read this Cornell Chronicle story.

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