A new study explains how the bloody red shrimp -- and other non-native species -- can travel across the Great Lakes. It's pretty simple: They hitch a ride in the ballast tanks of "lakers," the ships that travel around the lakes, but never make it out to the ocean.
Ballast water is commonly used to stabilize cargo ships. But when it is uploaded in one place and discharged in another, it can help expand the range of fish and other animals.
The study -- a project of the University of Wisconsin-Superior's Lake Superior Research Institute -- examined ballast water discharged in the western end of the lake. It documented five non-native species that were not yet established in the area.
One of them was the bloody red shrimp.
Bloody red shrimp came to the Great Lakes in the ballast tanks of ocean-going vessels, researchers say. They were discovered in 2006 in Lake Michigan and Lake Ontario, but had not yet been detected in Lake Superior.
(Last year, Great Lakes Today detailed the work of a Michgan researcher who was trying to determine whether the bloody red shrimp is harmful to the ecosystem of the lakes.)
The report "confirms a common sense assumption: lakers contribute to the spread of aquatic invasive species around the Great Lakes," Alliance for the Great Lakes President Joel Brammeier said in response to the study. "As such, all ships operating on the Great Lakes -- oceangoing and lakers -- must be accountable and stop introducing and spreading the biological pollution that is invasive species."
Meanwhile, the Lake Carriers Association called for a more detailed study -- over several years and on a larger number of ships. The association noted that it was a founding partner in the study, and worked in cooperation with the Minnesota Pollution Control Agency.
“It would be premature to base policy going forward on this limited data,” said Jim Weakley, president of Lake Carriers’ Association. “Let’s do some more work and get some more data to determine whether this study is telling us something new, or if these are limited data points that don’t reflect bigger issues and trends in the Great Lakes.”