UW-Madison News: Scientists say invasive species impacts much worse than thought

CONTACT: Jake Walsh, 651-717-5883, [email protected]; Steve Carpenter, 608-265-5248, [email protected]

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MADISON, Wis. – A new study shows the economic and ecological impact of invasive species in the Great Lakes has been dramatically underestimated. In fact, according to researchers at the University of Wisconsin-Madison, a single non-native species in a single inland lake has racked up $80 million to $163 million in damage.

The findings suggest a need to recalculate the cost of invasive species.

“Our study indicates that previous attempts to put a price tag on invasive species impacts haven’t come close to the true cost,” says Jake Walsh, a Ph.D. candidate at the UW Center for Limnology and lead author of the report, published in the Proceedings of the National Academy of Sciences.

The study might also inform the conversation about costs and benefits of the Great Lakes shipping industry. For decades, oceangoing ships have brought tons of cargo and tens of millions of dollars into the Great Lakes economy each year. But that manmade connection between the Great Lakes and the Atlantic Ocean has also helped bring in more than 180 non-native species.

Most studies, Walsh says, have focused only on invasive species that live in the five Great Lakes and looked just at direct costs of managing them – like the $20 million spent each year to poison invasive sea lamprey.

Instead, Walsh and his colleagues turned their attention to secondary invasions, or places where invasive species have moved since their introduction to the Great Lakes. The researchers also added “ecosystem services,” the benefits that humans derive from natural resources, to the equation.

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