In areas where cormorant colonies have been established research has shown drastic reduction in fish populations. In some cases the effect on aquatic ecosystems is so severe that recovery may take years or may not occur at all. Terrestrial damage to trees and shoreline habitat is also well documented in the vicinity of cormorant colonies.

Worse yet is potential impact cormorants’ may have on invading species. Research indicates that, where the birds have removed native species of fish, exotic species will move into the void in numbers that may effectively thwart recolonization by native species.

Cormorant overpopulation and its effects are well documented, and the provincial government has been urged to conduct research and implement immediate controls to stem the population explosion.

Among the most effective management strategies may be the removal of unnecessary legislative protections for the bird. Combined with adequate research, regulatory changes allowing cormorants to be treated as a pest species, numbers could be reduced to levels considered sustainable in the Great Lakes basin.

Cormorant populations have grown to historically high numbers in the Great Lakes region due to a number of factors including the development of many large fish farms in areas of the southern US where the birds winter. Readily available and plentiful winter food has increased survival rates for cormorants. Combined with improving environmental conditions including the reduction in use of pesticides like DDT, cormorant populations have soared.

However, management efforts have come under fire from animal rights advocates, and, leery of the public relations spectacle, the government of Ontario appears to be opting for a weak and piecemeal approach to the cormorant problem.

Egg oiling and extremely limited research appear to be the extent of the Ontario Ministry of Natural Resources cormorant management program which has been posted on the government’s Environmental Bill of Rights web site for public comment. The M.N.R. wants to have strong science to make decision on cormorants but the plan as suggested in the government’s proposal will not allow research to be conducted in any meaningful way.