Great Lakes Cormorant Management
Call to Cull Is Questioned By Scientists and Conservation Groups
Apr 9, 2008
The move to cull double-crested cormorants (Phalacrocorax auritus) around the Great Lakes flies in the face of environmental consciousness. An independent team of researchers has found little evidence to support this brutal action. The Canadian and US governments are asking for culls of cormorants under the guise of endangered species and habitat protection.
Cormorant Defenders International, a coalition of many of the major conservation and humane groups in both countries, is working to stop the US Fish and Wildlife Service and Parks Canada from proceeding with these actions. In Canada they have succeeded in getting a court order to delay the cormorant cull until a federal judge reviews the situation.
Double Crested Cormorant History
Listed as endangered in several states in the 60s and 70s, the double crested cormorant population has only recently rebounded from being seriously depleted, largely due to pesticides such as DDT. Today this cormorant is facing persecution by man under the guise of protecting endangered plants and animals.
Cormorant Culls Issues
- Impacts on sport and commercial fisheries: An independent study, financed, and later ignored, by the US Fish and Wildlife Service, found that double crested cormorants had no significant impact on sport and commercial fishing in this area. For example, yellow perch (Perca flavescens) is one of the species of concern but the study found that neither the cormorants which consumed 1% of the legal size perch, nor the sport fishing community which caught 2.5% of those perch, had an impact on the perch population.
- Impact on other nesting water birds: The study found that many of the declines cited as a reason for removing double crested cormorants, began before the cormorants recolonized the area. Colonial nesting water birds use nesting sites in cycles and abandon them at regular intervals. It is, however, possible that the cormorants do take over some nesting areas in some situations. To quote the authors: “Displacement may occur locally but no demonstrated regional or population level impacts have been established” Another factor to consider in the water bird declines is the invasive alien species, such as zebra mussels, which are affecting the overall health of the Great Lakes and fish eating birds in particular.
- Impacts on vegetation: These are clear. Double crested cormorants do strip trees to make their nests. Their guano is acidic which is deadly to many types of plants. But the impacts have never been as severe as they are now, even though high populations existed when Europeans settled the area. The researchers contend that dredging, deforestation, erosion and interrupting water flow in rivers has magnified the problem by reducing the number of available breeding sites.
Arguments Against Culling Double Crested Cormorants
- This expensive and inhumane program is not likely to work. Once the cormorant population in an area is reduced, more birds will move into the unoccupied territory.
- Graphic video of cormorant culling shows why the process is not humane. Many of the birds were injured rather than killed, then left to die slowly from starvation or predation.
- The other water birds, which were supposed to benefit from this program, are scared off their nests by culling activities. Even tactics such as egg oiling to prevent hatching create a major disturbance in the nesting area, putting the eggs and nestlings of all the birds at risk.
Targeting a single species, such as the double crested cormorant, despite the fact that the problems of the Great Lakes ecosystem are complex and long standing flies in the face of effective ecological management. A more holistic approach to recovering the health of the Great Lakes region would make a great deal more sense.
Source: Wires, LR, FJ Cuthbert, DR Trexel, and AR Joshi. 2001. Status of the Double-Crested Cormorant (Phalacrocorax auritis) in North America. Final Report to USFWS (This paper can be accessed from the US Fish and Wildlife Service)
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