SCARBOROUGH, Maine — Abigail Carroll, the owner of Nonesuch Oysters, has been raising oysters in the Scarborough River for two years near the railroad bridge and Seavey’s Landing.

Farm expansion plans were approved July 16 by the Maine Department of Marine Resources, with a three-year lease on a site adjacent to 4.5 acres she already uses to moor floating mesh bags of virginicus oysters.

Carroll will gain more room for the second stage of oyster cultivation, in a setting DMR officials have determined provides plenty of water flow and nutrients for her crops, without interfering with navigation or other river uses.

She and Scarborough Harbor Master Dave Corbeau are looking to use space on the Pine Point Municipal Pier for the first stage of growth, which occurs in oyster nurseries called upwellers. Carroll’s upwellers are now at the Biddeford Pool Yacht Club.

“I’ve got livestock here,” she said at the club, inspecting a lobster tub containing five-gallon buckets of germinating oyster spats. The spats, which feel like barley to the touch, range in size from a wood tick to a pencil eraser, and are fed and nourished by water pumped at 150 gallons a minute.

Carroll wants to move at least one upweller, in part because her staff does not get to see many of the infants they will eventually tend.

“They are kind of missing the fun part, you can see growth every two days,” she said.

As the oysters mature and develop shells, Carroll and her staff then move the spats to mesh bags moored in the Scarborough River. Mature oysters are sold to a wholesaler that supplies restaurants throughout greater Portland.

Corbeau said he expects permits will be needed from the DMR and U.S. Army Corps of Engineers to set up an upweller on the pier, but not from the town.

“The process should not be a huge issue,” he said.

Raising spats provided by nurseries on the Damariscotta River was a large step in expanding Nonesuch Oysters, Carroll said. Biddeford mill owner Chris Betjemann helped build the upweller and modify the design to incorporate the five-gallon buckets inside lobster tanks.

Just as she planned to install and operate the upwellers in Scarborough, an inundation of rain runoff decreased salinity levels to a point where the spats would have died.

Carroll sought help from the yacht club, where she is a member, and Biddeford officials to open the upwellers adjacent to the club.

Tending and cleaning the upwellers is constant work, and spats are fed with the flow of abundant phytoplankton in waters off the yacht club.

“Murky water is good,” Carroll said. “I’m totally obsessive; I am here all the time.”

In September, Carroll said she will shut down the upwellers and place even the smallest spats into bags on the river in advance of winter.

In Scarborough, she relies on a staff of current or recently graduated college students to check the moored bags, shift growing oysters, harvest those ready for market, and get rid of predators like mussels.

The farm was initially stocked with some maturing oysters to ensure the company could begin selling and have cash flow. Now the smaller ones planted in 2010 are also reaching market size: between 2 and 3 inches wide.

Carroll said about 2,000 oysters were harvested last week, and Nonesuch employee Russ Chandler said he harvested about 300 on Tuesday afternoon.

Initial efforts to grow Maine-raised French belon oysters were unsuccessful, but Carroll said she would like to try again, and import stock from France for the farm. Carroll is also expanding retail sales of the oysters to the Pine Point Fisherman’s Co-op and Ken’s Place on Pine Point Road.

Carroll’s team of aquatic farm hands includes Kim Little, a Cleveland native who also works at the Gulf of Maine Research Institute, and Bowdoin College sophomore Ryan Mancini, an economics major.

“You can’t beat working on the water,” Little said as she held a bucket of freshly harvested oysters next to her tanned, mud-flecked legs.

Carroll called Little a “rock star” for the work she does year round, even as oysters hibernate in the winter.

“The key to [working in] February is finding gloves,” Little said. “As soon as I find the perfect pair, I’ll buy them in bulk.”

When the expansion is complete, Carroll estimates she will be raising about 80,000 oyster annually. She holds no illusions they will all fill plates, but feels good about how things have progressed in the third year of her five-year business plan.

“That’s why you start out with a lot of oysters,” she said.