FRANKLIN – Concerns over possible habitat competition between oysters and horseshoe crabs in Taunton Bay dominated a hearing Wednesday on a proposed aquaculture operation.

The hearing, which started around 10:30 a.m., was going strong late Wednesday afternoon, with only one intervenor out of four having testified against the proposal.

Public comments will be considered in a recommendation by Hearing Officer Mary Costigan to the commissioner of the Department of Marine Resources, who must make a decision on the application by mid-October.

Applicant Michael Briggs and consultant Chris Davis began testimony, explaining the project and arguing the proposed operation would not adversely affect Taunton Bay’s ecosystem.

Davis, who has farmed oysters in the Damariscotta River for 20 years and taught Briggs how to cultivate oysters, told 40 people attending the hearing that the proposed oysters are not considered an invasive species.

“Eastern oysters are native to Maine,” Davis said. “It’s not considered an exotic species to Maine waters.”

Under the proposal, Briggs would raise oysters in trays floating on the surface of a proposed 1.19 acre site leased at the mouth of Hog Bay, which drains into Taunton Bay, and is a mostly exposed mud flat at low tide.

In the fall, oysters would be transferred to a 6.28 acre site nearby in Taunton Bay, where they would grow to maturity on the bottom.

The proposed 150 floating trays would be spaced inches apart on 12 lines moored to the bottom of Hog Bay, Davis said. Each line would be approximately 15 to 20 feet apart to allow boat traffic between them, he said.

After the oysters are transferred to the bottom, they grow in densities of 10 to 15 oysters per square foot, Davis said.

Under questioning by Steve Perrin, president of the environmental group Friends of Taunton Bay, Davis said there is no evidence to suggest oysters grow naturally in Taunton Bay or have ever been indigenous there.

“Here I see a fuzzy line,” Perrin said. “How can they be native if they won’t reproduce [in Taunton Bay]?”

Davis said the apparent inability of oysters to reproduce in Taunton Bay can be attributed to many factors, but added there is evidence that oysters have bred naturally in other parts of Maine for thousands of years.

Davis, under questioning by Perrin and others, insisted he has no financial interest in Briggs’s operation, but admitted he hopes Briggs succeeds because the man is a former student.

Davis said in the Damariscotta River, he’s seen no indication that horseshoe crabs and oysters compete for food or territory.

“They inhabit very similar habitats,” Davis said. “They’ve managed to coexist pretty well.”

Sue Schaller, a scientist conducting a 10-year study of horseshoe crabs in Taunton Bay, said Briggs’s application to farm oysters should be rejected.

She said introducing oysters to Taunton Bay could skew the results of her study and would force horseshoe crabs to compete for habitat.

Schaller, under questioning by Department of Marine Resources biologist John Lewis and Penobscot oyster farmer Jesse Leach, defended the practice of handling the horseshoe crabs as she and volunteers tag the animals.

“By handling them quickly, you minimize the period of disturbance,” Schaller said.

Leach said he was concerned Schaller and others harm minuscule newborn horseshoe crabs by walking along the shore of Taunton Bay while counting adult crabs.

“I think you’re killing what you’re trying to save,” Leach said.

Also expected to testify in the matter Wednesday besides state officials were Perrin, Roger Fleming of the environmental advocacy group Conservation Law Foundation and Franklin resident Susan Braley, who owns waterfront property on Taunton Bay.