MONTPELIER, Vt. – A single Atlantic salmon is spending the summer in the White River watershed, only the second time in more than 200 years that biologists have tracked one that far up the Connecticut River.

It’s one of the few pieces of good news in the Connecticut River salmon restoration project this year. Only 41 adult salmon returned to the entire Connecticut River this spring.

Over the last two decades, anywhere from 200 to 400 fish returned to the Connecticut River annually. This year’s total is the lowest since 1983, when 39 fish returned.

Of the 41 captured this year, all but four were taken from the water to be used as brood stock at salmon hatcheries.

“The fact that we’ve got fish returning to the White River is really a high point. It shows that success can be had,” said Angelo Incerpi, the operations director for the state Department of Fish and Wildlife.

The White River flows into the Connecticut at White River Junction.

Biologists are still trying to learn why the numbers of Atlantic salmon are falling dramatically throughout their range.

“It’s generally recognized as a problem in marine conditions in the North Atlantic,” said Jay McMenemy, a state fish biologist. He used a radio tracking device to track the fish in the White River area as it swam up the Connecticut.

“For the last few years marine survival has been plummeting everywhere,” McMenemy said. “This same thing is happening in Canada and Scotland and everywhere else” Atlantic salmon are found.

When European settlers arrived in what is now New England, Atlantic salmon were plentiful and easy to catch. But they disappeared in the late 17th and early 18th century after power dams were installed along the Connecticut River, making it impossible for the salmon to reach the streams where they were hatched.

In the early 1980s, federal and state officials from Connecticut, Massachusetts, Vermont and New Hampshire started working with utilities to clean up the Connecticut River, to install fish ladders or elevators over dams and to begin a stocking program.

Officials are trying to stock 10 million young salmon, or fry, a year in the entire four-state Connecticut River watershed.

When the fry reach 7 or 8 inches they swim down the Connecticut and out into the ocean. They then spend three or four years near Greenland before they return to the stream where they were released to breed.

One Atlantic salmon was tracked to the White River watershed in the late 1980s. The fish there now is only the second known to have made it there in the last 200 years.

The fish are protected and illegal to catch. But an angler in Vermont caught the salmon in the White River area, a female, earlier this summer. He promptly let it go and told state officials.

“It’s a beautiful big fish,” McMenemy said. “To let that go is wonderful.”