Smallmouth bass make up only 1 percent of cormorants' diet, but cormorants do eat bass as large as 12 inches in length. Throughout the Great Lakes, nutrient input has declined as a result of pollution controls, water clarity has improved and overall biological productivity has declined. Although other areas of Lake Ontario and Lake Erie have been subject to the same environmental factors, smallmouth bass stocks are thriving in areas not subject to intense cormorant predation. Beginning in 1989, mortality of smallmouth bass ages 3 through 6 in eastern Lake Ontario increased significantly as cormorant populations grew. The relationship between the relative mortality of smallmouth bass ages 3 to 6 and the numbers of nesting pairs of cormorants on Little Galloo Island during the period 1976 to 1994 is highly significant.
Cormorants are opportunistic feeders.
As the lake's alewife populations declined, cormorants were forced to concentrate on warmwater fish such as smallmouth bass. As a result of these findings, DEC now will seek to determine the optimal cormorant population level and the best means of reaching that goal. DEC hopes to identify an appropriate course of action by spring 1999. We need to find an ecologically and economically sound balance in the cormorant and fish populations. The warmwater fishery of eastern Lake Ontario is an important part of the local economy.