GREENFIELD — For decades, it was assumed the federally endangered shortnose sturgeon did not live upstream of the Turners Falls dam on the Connecticut River, although two confirmed sightings in 2017 and 2022 raised some compelling evidence.

New environmental DNA analysis from the Connecticut River Conservancy, though, may support those sightings, as it shows a population of the prehistoric fish could possibly live above the dam.

The Greenfield-based nonprofit announced Thursday that environmental DNA (eDNA) analysis from water samples collected in Northfield; Vernon, Vt.; and Westmoreland, N.H., this summer detected sturgeon genetic material.

“Our study is ongoing; this is the first round of data collection,” said Kate Buckman, the Connecticut River Conservancy’s New Hampshire river steward. “The data is preliminary, but compelling.”

Buckman conducted the study in partnership with James Garner, a Ph.D. candidate at the University of Massachusetts Amherst.

Shortnose sturgeon live in rivers and coastal waters from Canada to Florida, and the earliest known remains in the fossil record date back more than 70 million years to the Cretaceous period, according to the National Oceanic and Atmospheric Administration. Shortnose sturgeon have been protected under the Endangered Species Act since 1967 and are categorized as an “endangered” species.

Up until 2017, it was accepted that the fish did not live upstream of the Turners Falls dam. That changed when a fisherman in Vernon, Vermont, hooked one and NOAA confirmed the sighting. Then in 2022, another angler filmed a sturgeon swimming at the basin of the Bellows Falls dam, according to U.S. Geological Survey biologist Micah Kieffer, who said in an interview in late July that until these sightings were confirmed, it was “firmly understood” the fish did not live that far north.

Kieffer also previously said the sturgeon population is relatively small in the Connecticut River in general, as he said it is estimated there are about 10,000 adult fish in the entire river. The Hudson River, for comparison, has about 60,000 adult shortnose sturgeon.

Those sightings, while confirmed by the federal government, were a chance of fisherman’s luck, rather than a scientific study. Buckman said those two events were part of the motivation of undertaking the Connecticut River Conservancy’s research.

In the last month, two shortnose sturgeon were found swimming in shallow pools below the Turners Falls dam, which were scooped out by Kieffer and other officials, evaluated, tagged for research purposes and released back into the river. At the time, Kieffer noted shortnose sturgeon are generally rare in the Turners Falls area.

To obtain the DNA samples, Buckman and Garner, with the help of field volunteers, collected samples from the bottom of the Connecticut River and brought them back to the lab for eDNA analysis. As fish swim through a body of water, they shed genetic material contained in slime, excrement, scales and other parts of their bodies, which remain in the water. The sampling sites were identified using existing research from Kieffer, as well as information from Northfield resident Joe Graveline and Annette Spaulding of Rockingham, Vt..

At the lab, the water samples are filtered and DNA is extracted from the material remaining on the filter. From there, probes designed to bind DNA from the target species is then used in what’s called a qPCR reaction, which amplifies the targeted DNA strand and then copies it. The accumulation of DNA copies can then correlate with how much DNA was present in the water, generally meaning the more DNA copied, the more fish there are in the water.

“Our results demonstrate that there are detectable levels of shortnose sturgeon DNA at multiple locations within the reaches of the Connecticut River upstream of the Turners Falls and Vernon dams,” Garner said in an announcement about the findings. “The strength of the hits relative to our positive controls signals to me that these endangered fish are present throughout these upstream reaches but likely at lower numbers than where they exist farther south.”

Buckman said an eDNA analysis was conducted on these parts of the Connecticut River six years ago, although that study had no positive hits, which “potentially” could be a result of the study using surface water samples, rather than from the riverbed, where sturgeon typically live. Luck also could be a factor, as Buckman noted the previous study might have just picked a time when the fish were not in that particular area.

When working with a federally endangered species, Buckman said eDNA analysis is an effective method of research, as it takes far less time to collect water samples than netting or catching fish that are scarce by definition. Additionally, federal law prohibits the targeting, catching or disturbance of endangered species.

“It’s a good tool to work with rare species,” Buckman said. “I personally, even though I’ve done it, still find it amazing that you can still sample some water and say, ‘Yes, this fish is around here somewhere.’ ”

Buckman emphasized this is still preliminary data and more sampling will be done in the fall and winter to see whether more DNA can be found, which could better support the idea that there is a population of shortnose sturgeon above the dam, rather than a fish or two that managed to bypass the dam.

“It’s hard to quantify how many fish there are from the results,” Buckman said. “The fact that we have hits between Turners Falls and Vernon and between Vernon and Bellows Falls … that suggests certainly there is a likely small, but real, number of fish.”

Chris Larabee can be reached at clarabee@recorder.com.