Permits were previously required to ship live fish. The inputs and outputs of the farm are also highly regulated. Fingerlings are purchased from hatcheries which have the same requirements as a cage farm plus the Ontario Ministry of Environment Certificate of Approval and often a Department of Fisheries and Oceans Fish Health Certificate. Processing plants are subject to federal and provincial inspection. Feed manufacturing also involves tight regulatory controls.
Big brother watches from cradle to grave.
Reasonable regulations must place fish farming in the context of the real world, which is not a pristine place. Virtually all of the dominant coldwater species in the Great Lakes are introduced, from zooplankton through forage fish to the top predators. There is no natural coldwater ecosystem to preserve so don't pretend there is. Managers should be considering the needs of all users of the resource, not just anglers, and the benefits to society as a whole. Objectively, fish farming can be one of the most environmentally friendly activities we humans can undertake.