Oceangoing Ship Ban Explored

"Biological anarchy in the Great Lakes has a growing chorus of scientists and policymakers exploring a radical, simple solution: ban all oceangoing cargo ships."

But shipping-industry officials warn that the economic impact of such a drastic move could hurt Midwest industries that rely on foreign goods.

"The problem starts when nonnative freshwater organisms are sucked into ships that take on ballast water in Europe for stability.Even when the freshwater is exchanged for saltwater in the ocean -- a requirement for Great Lakes-bound ships since 1993 -- many of the critters survive in the muck at the bottom of the tanks. When ships dump ballast water into the Great Lakes, some organisms are spewed out and gain a foothold."