On Friday, the U.S. Supreme Court will reconsider closing the Chicago canal locks temporarily to prevent the spread of Asian carp, according to Michigan Attorney General Mike Cox. Attorney General Lisa Madigan has previously urged the justices to uphold their January ruling, which allowed local officials to keep shipping locks open along the Mississippi River system. Environmentalists have called for even more drastic action that would separate the two waterways permanently.

On Monday, fishing crews who have been searching the canal system near Lake Michigan for a month formally announced they did not catch one Asian carp. Scientists had warned that finding the fish using these procedures was too difficult to execute. DNA testing has already yielded evidence that the invasive species has moved into Lake Michigan.