If I have time to reply verbally—I can also reply in writing—yes, fishery officers are limited as peace officers restricted to the Fisheries Act. For anything to do with public safety or other Criminal Code offences that fall beyond the Fisheries Act, they do not have peace officer powers.
In addition, they do have the ability, for obstruction or assault, to take actions with peace officer powers if such things occur, but there is still a referral for investigation to a peace officer of the law enforcement of jurisdiction.