EAST MACHIAS, Maine — Thirty students of Washington Academy’s science course on coastal ecology made the half-mile walk Tuesday afternoon from the East Machias school to the nearby Downeast Salmon Federation, which science instructor Don Spranger uses regularly as a fisheries laboratory.

The students watched staff fisheries biologist Jacob van de Sande assemble an incubator that soon will be used to help thousands of North Atlantic salmon eggs grow into three-quarter-inch fry for release into the adjacent East Machias River.

The students on hand Tuesday also met Peter Gray, a 70-year-old Scotsman who invented the system now being installed. Gray has been working as a consultant to the facility as it prepares to greatly expand its hatchery operations.

Some students busied themselves examining eggs that are now developing in trays submerged in water extracted from the river. As the eggs hatch, the tiny salmon will be moved into larger tanks.

“This facility is an extension of our classroom,” Spranger said Tuesday. “There are about 90,000 salmon eggs here, and the kids come in and remove any dead eggs that are in trays, and they check the water system to be sure that everything is running smoothly.

“The hatchery remains a work in progress and will eventually include a classroom, where kids will have access to lab equipment and water testing equipment,” Spranger said. “But right now it’s a working hatchery.”

Sophomore Taylor Roos, 15, may be a farm girl who is growing up on a Jonesboro dairy farm, but she says she has taken to the hatchery with the eagerness of a salmon swimming upstream.

“It’s really, really exciting to get to work with what is an endangered species,” she said Tuesday after her stint of culling dead eggs for those infected with fungus. “It’s exciting to watch them hatch out of their eggs and grow. They’re adorable. Last year, with our last batch, a couple of us were able to come down and clip one of the top fins so that we know which salmon are ours. That was really fun because we got to take them out and hold them and feed them. It’s just really exciting to be a part of.”

Ben Rose, 17, a junior from Jonesboro, said the coastal ecology class covers a lot of academic territory, but he finds that his work at the hatchery allows him to have a positive impact on a threatened environment.

“Sometimes eggs die, and we’ll come down here and help count the dead eggs we find, as keeping track of the numbers is very important,” Rose said Tuesday. “I feel like what we are doing down here will make a positive change and really has an impact on the community and on the planet.”

Once the young salmon these students are helping to rear are large enough for release into the East Machias River, Spranger’s students will be on hand to assist with that process, too.

“And while we are on the riverbank, we’ll be planting trees along the shoreline,” he said. “The trees provide shade that keeps the water cool in the summer and also prevents bank erosion.”

The young trees being readied for that process now decorate the hatchery’s front lawn, tucked in between an array of photovoltaic solar panels and a vertical wind turbine that help to power the facility.