On Wednesday, the Center for Aquatic Conservation at the University of Notre Dame in Indiana brought forward a report according to which, the invasive species that have managed to find their way into the Great Lakes are making the regional economy lose about $200 million annually.

The problem’s roots go way back, to the moment when the Great Lakes were connected to the sea almost 50 years ago. As found in the report, since the St. Lawrence Seaway was opened in 1959, no less than 57 species have been brought in the lakes by vessels. Among the 57 problematic species, two of the most damaging were identified to be the zebra and quagga mussels.

Out of all the affected activities and industries, sport fishing seems to be doing the worst, as in 2006, it recorded losses of $123.5 million.

Environmentalists are trying to get the US Senate to approve a bill in order to install systems for eliminating the species that have interfered with the local ecosystems. If nothing is done before the Senate’s August recess, some say the bill’s prospects would be rather dim.

Last year, the Notre Dame scientists estimated economy losses of about $300 million; this year’s report however, brought the sum down to $200 million. The total only covers the eight US states in the Great Lakes region. As David Lodge, director of the university's Center for Aquatic Conservation, said, Canada has suffered a fair ammount of losses as well.