People opposed to a fish farm on Nova Scotia's south shore held a demonstration at Province House in Halifax Wednesday, drawing attention to their worries that the aquaculture project will hurt traditional fisheries.

The group of about 25 people from the Friends of Port Mouton Bay organization, said it is their understanding that the proposal from a New Brunswick-based company for a second salmon farm in the Queen's County bay will get federal approval in an assessment expected in March.

The group claims an existing salmon farm owned by the same company has left a layer of excrement on the seabed over much of the bay.

Robert Swim, a lobster fisherman in the area, said he believes adding a second, larger farm, as proposed, would only further pollute the bay.

"The area that they want to take has been so valuable to us for years and years and years, for a safe haven, and it's deep water and there's lobster there," Swim said.

"We just can't give up that much, almost three-quarters, of our lobster bottom to almost anything, it doesn't have to be salmon farming, to anything that wanted to come there. We're going to have to say 'no' to that because we need that. So it's survival to our fishery."

Swim said he also believes that more fish farms would hurt tourism in the area.

Darlene Norman, spokeswoman with the Friends of Port Mouton Bay group, said she and other opponents of the proposed farm are disappointed the federal Department of Fisheries and Oceans, as well as the provincial Department of Fisheries and Aquaculture, have not been more open to their concerns.

"Everything in the basket in the Department of Fisheries and Aquaculture, is now, and aquaculture," she said. "They've been a big lobby group for 20 years, and southwestern Nova Scotia has been identified as the place in the province for large fish farms."

Fisheries and Aquaculture Minister Ron Chisholm told CBC News that he was not aware of the fish farm proposal passing an assessment, and said the final decision on whether the project goes ahead rests with him.

"There is still quite a process to go through. Has there been a decision made? No. But the buck lies with me," Chisholm said Wednesday.

"When the time comes, I'll make the decision, and the community will be well aware of what is happening."

Aqua Fish Farms Ltd. currently operate a salmon farm in the area, in the eastern harbour of Port Mouton Bay, off Spectacle Island.

The proposed new salmon farm would be located off the west side of Port Mouton Island, across from what local residents describe as one of the best beaches.

According to Friends of Port Mouton Bay, the new farm would be stocked with 300,000 fish each in two separate production areas.

The group has sent a letter to federal Fisheries Minister Gail Shea asking her to put a moratorium on aquaculture expansion in Port Mouton Bay.