Barrels of mussels being bred at the state’s fish hatcheries are awaiting release into the region’s rivers, helping to restore these dwindling but important species.

For decades, the N.C. Wildlife Resources Commission has raised fish — some 8 million a year at a network of six hatcheries in the state — favored by recreational fisherman. But the foray into propagating mussels marks new ground.

Both the Marion and Table Rock hatcheries are propagating freshwater mussels. The Cheoah River near Robbinsville has already become the new home for some of the mussels bred in captivity.

The biologists involved in the effort are getting a chance to observe mussels up-close and in person, learning about mysterious elements of their life cycle. Determining how mussels reproduce — like where and what time of year they mate — brings biologists one step closer to saving them from extinction. Mussel larvae spend part of their life hanging out on a host fish, but which species serves as a host for various mussels isn’t always known either.

“This information is critical to saving some species from extinction,” said Steve Fraley, an aquatic biologist with the Commission who spearheads the program.

The hatchery set-up will also allow biologists to experiment with how much pollution is too much for mussels.

Mussels are like tiny lungs for the aquatic ecosystem. They are constantly filtering water through their bodies, straining out edible morsels and extracting oxygen. Mussels are also a food source for animals like beaver and otter.

Mussels have been in peril for a host of reasons. The top enemy of mussels is sediment, which clogs their siphons and smoothers them. Chemical pollution is bad for the mussels as well.

The ability of mussels to repopulate on their own is hampered by the promulgation of dams. Many mussel species hitchhike on fish as larvae, and if fish get blocked by a dam, so the mussels hitching a ride. Mussels can end up stuck in between two dams, unable to co-mingle and breed with neighboring colonies.