When Roger Klindt, an aquatic biologist, gets a call from someone who has spotted a sharklike fish in a river or a lake in New York state, he is assured that his life’s work is paying off.

Klindt, who has worked for the state Department of Environmental Conservation for 31 years, has been crucial in efforts to restock New York waterways with torpedo-bodied lake sturgeons, a threatened and ancient species.

“When I started, no one saw sturgeon. Period. The end. Even the biologists here had not seen one,” he said. “Now it’s a pretty good bet that if I was assigned to go out and catch a sturgeon or two, I could probably go do it.”

Last week, more than a dozen biologists gathered in Massena, a small upstate river town, for the department’s annual artificial propagation, also called egg-taking.

The biologists caught about 120 lake sturgeons with nets in the St. Lawrence River. The fish are drawn to the spot, south of the Moses-Saunders dam, during early summer when they regroup before spawning.

The researchers collected sperm and harvested eggs to fertilize. Then about 130,000 fertilized eggs were sent to hatcheries, where they are expected to hatch in the next week.

Once abundant in the Great Lakes region, the sturgeons, which can live over 100 years, have been nearly wiped out nationwide because of overfishing, pollution and the construction of dams, according to the agency.

From the 1800s to the 1950s, lake sturgeons were sought after for their caviar and meat, Klindt said.

“Globally, there are over 20 species of sturgeon that have been around relatively unchanged since the times of the dinosaurs,” said Scott Schlueter, a biologist at the U.S. Fish and Wildlife Service, which provides the conservation agency with logistical support. “And in one human life span of about 100 years, we’ve almost wiped them off the globe.”

The fertilized eggs from the St. Lawrence River were sent to hatcheries in Genoa, Wisconsin, and Constantia, New York. There, sturgeons will be raised until September, when they will be about 6 inches long and ready to be released.

The goal, Schlueter said, is to successfully restock 10,500 sturgeons this fall.

Researchers implant a small tag in the sturgeons, which allows a propagated fish to be scanned and recognized.

“We’ve been seeing the payoff with record number of sturgeons showing up in spawning beds,” said Jeff Gerlach, a manager of environmental studies at the New York Power Authority, the state-owned utility that has funded the effort since 2003.

And after 25 years and 100,000 restocked sturgeons, biologists are now working to measure how successful the fish have been at reproducing in the wild.

“We’re trying to re-establish these fish where they were historically,” Klindt said.