Two patrol frigates from the Royal Canadian Navy did exercise manoeuvres off Peggys Cove on Thursday. (CBC)

Lobster fishermen on Nova Scotia's South Shore say they're worried ships from the Royal Canadian Navy are tearing up their traps and wrecking their livelihoods.

Anslie Hubley said on Thursday he witnessed two patrol frigates doing exercise manoeuvres off Peggys Cove, in the middle of lobster fishing grounds.

Hubley said he wasn't confident the patrol ships could move around the lobster traps.

"They can't turn the ship around in Halifax harbour without running into something, how are they going to do it when they're moving around lobster traps?" he asked, referencing a Nov. 4 incident when HMCS Preserver rammed into a tied-up floating dock in Halifax harbour.

Lobster fishermen tried to stop the navy ships by using a marine radio, but Scott Hubley said those calls were ignored.

"Our people were calling them and they wouldn't answer," he told CBC News on Thursday.

"They were in total darkness," said Anslie Hubley.

"I don't know why."

Lobster traps are tethered to the surface by long lines, which can get caught in a passing ship's propellers. There's a concern both the catch and the traps will be destroyed.

The fishermen said they haven't seen any damage because the traps can't be assessed until the seas calm down.

A spokeswoman for the Royal Canadian Navy confirmed its ships were conducting exercises in the area and said they were announced several weeks ago.

She said the navy is always vigilant and on watch for any fishing gear and if there is damage, it will be assessed.

This isn't the first time the navy and fishermen have been in conflict, but Scott Hubley said it comes at a time when lobster prices are low and the quality of some of the catch is poor.

"I know they're just doing exercises, but why do the exercises in the middle of the lobster season?" he said.

"There's all kinds of places to do it."