The zebra mussel’s aptitude as an invader is rivaled only by its skill as a lobbyist. In 1990, while the mussels’ mischief on the Great Lakes reached its height, Congress passed a law aimed at regulating ballast water — the water, hauled by empty ships for stability and balance, that is also the mussels’ most likely transcontinental carrier. By 1993, the U.S. Coast Guard required ships coming into the Great Lakes from overseas to exchange their ballast water on the open ocean, the first such regulation in the world.
Yet these pioneering rules, along with similar regulations in Canada, haven’t stopped the flow of aquatic invaders into the Great Lakes. That’s partly because ballast-water exchange isn’t always effective and is sometimes avoided for safety reasons, says Phyllis Windle, an invasive-species expert with the Union of Concerned Scientists.
It’s also because some 90 percent of ships enter the region carrying cargo instead of ballast water, and so declare “no ballast on board,” or NOBOB status. These NOBOB ships can still carry invasive organisms in residual water in their ballast tanks, and they can easily dump the invaders when they unload and reload cargo, says Hugh MacIsaac, an invasive-species researcher at the University of Windsor in Ontario. One possible solution, currently recommended but not required by the Coast Guard, would be for all ships to clean their ballast tanks with salt water before entering the St. Lawrence Seaway — a routine known as “swish and spit.”
The 1990 federal law on ballast water was reauthorized and expanded in 1996 as the National Invasive Species Act, but it has been awaiting a second reauthorization since 2002. Efforts to revive and further strengthen it have so far failed. In 2004, after several years of delay, the Coast Guard made ballast-water exchange mandatory for all U.S. ports.
Even so, several states frustrated with the gaps in federal policy — notably California and Michigan — have passed or are considering their own ballast-water legislation. The International Maritime Organization, an agency of the United Nations, recently reached an agreement that would establish worldwide standards for ballast-water practices, including chemical treatments and other technologies that could replace ballast exchange. The agreement, however, has not yet been ratified by enough countries to take effect, and many advocates criticize it as ambiguous and lacking in strict deadlines.
While the policy tussle continues, unwelcome and potentially costly species continue to establish themselves in the Great Lakes. “What if the next invader is a human pathogen?” asks Gail Krantzberg, a professor of civil engineering at McMaster University in Ontario and an expert on Great Lakes policy. “Do we have the billions of dollars that would be required to deal with it? Probably not.”
This story is a sidebar to the feature:
Quagga mussels – an extraordinarily prolific and costly invasive species – have appeared in Lake Mead, and no one is sure how to keep these unwanted newcomers from infesting the West.