Invasive Species in Ship Ballast

Capt. Pat Nelson gazes about the cavernous, mud-slicked interior of the ballast tank deep in the bowels of the 1,000-foot cargo ship, Oglebay Norton.

“This thing holds more than a million gallons, and that’s just one tank,” Nelson says. “How are you supposed to sterilize this much water?”

The question is at the center of a debate that has turned the lowly ballast tank into one of the Great Lakes region’s hottest political battlegrounds. The issue: how to stem an invasion by ballast stowaways, such as the hated zebra mussel without sinking the shipping industry.

A Soupy Mixture

Ballast is a soupy mixture of water, sediment and seaweed whose weight keeps ships stable during voyages. But it’s also home to a vast array of aquatic organisms that end up being hauled thousands of miles and then released into new territories as ships dump ballast while taking on cargo in port.

Once in their new homes, the uninvited immigrants can multiply quickly and wage war on native species, gobbling up their food and stealing their habitat.

Among the most notorious are the parasitic sea lamprey, which decimated the native trout population by the mid-1900s, and the zebra mussel, which arrived in the late 1980s and did hundreds of millions in damage by clogging water pipes.

Governments around the world are trying to close their borders to unwanted biological travelers. But the sense of urgency is particularly strong in the Great Lakes, where nuisance aliens have drastically altered the world’s largest surface fresh water system.

“It’s an ecological disaster,” says Mark Coscarelli, an environmental specialist with Michigan’s Office of the Great Lakes.

“Exotic species are the No. 1 issue facing the lakes, the single largest threat,” says Ken Sikkema, chairman of the Michigan Senate’s environmental affairs committee.

An estimated 145 aquatic foreigners have taken up residence in the Great Lakes ecosystem since the early 1800s — many, though not all, brought by ballast. More are on the way, scientists warn.

Shipping companies say they have made good-faith efforts to flush out the pests. And the Coast Guard requires ocean freighters to dump their ballast and take on more water before entering the lakes via the St. Lawrence Seaway.

Critics say more is needed.

Sterilization a Problem

Bills proposed in the Michigan, Minnesota and New York legislatures would order shippers to sterilize ballast, using government-approved methods of killing every critter, before dumping it into waters under their jurisdiction. A similar bill is pending in the U.S. House, and the Ontario provincial legislature also is considering ballast legislation.

Possible ballast sterilization methods include heating water, chemical disinfectants, ultraviolet light, screens and filters. But no workable technology has been devised.

Shippers say the bills make unrealistic, costly demands that could scuttle the industry in the region. They acknowledge the problem exists and say they are progressing — slowly — toward a solution. But for now, they insist, there is no way to completely purge live exotics from ballast.

“We’ve been working for almost a decade. The technology simply does not exist,” says Ray Skelton, government affairs director for the Duluth, Minn., Seaway Port Authority.

Even if a successful program were found, shippers say, it could cripple them by requiring costly upgrades and fees not levied against trains, trucks or ships that visit only ocean ports.

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