A low-cost, low-tech method for killing many of the potential hitchhikers in oceangoing Great Lakes freighters shows some promise for stemming the tide of invasive species - but it's probably not the ultimate solution.
Experts say the Lakes have seen 185 foreign species invade over the last century, and there are 58 foreign species still posing a moderate or high risk of invading the Great Lakes in ballast tanks.
A decade ago researchers were finding a new species in the Great Lakes every 28 weeks on average - but it's been six years since the last species was confirmed. The best guess for the decline? Rules requiring ships to exchange ballast water far out at sea. It's refered to as "swish and spit" after the dentist office routine. A stiff dose of saltwater can be very effective at killing freshwater invaders hiding in ballast tanks.
Ballast water exchange was done voluntarily since 1993 but has been required by the U.S. and Canadian governments since 2006. It's an inexpensive and effective first step.
Supporters believe "swish and spit" is killing up to 98 percent of the freshwater organisms that may be lurking in ballast tanks. But environmental groups argue the risk of assuming swish and spit will stop all species is too great. Clearly, the stakes are high.
The zebra mussel and sea lamprey - both alien to the Midwest - have already raised havoc in the Great Lakes basin. Mussels clogging pipes at water and power plants cause an estimated $100 million of damage each year; lampreys are decimating fish stocks in some areas and Canada alone spends $15 million a year to control them.
With these huge economic impacts, it's fitting that legislators take further internationally coordinated steps to stop the invaders. The risk of another zebra mussel getting into the lakes is simply too high to accept. Another level of protection is needed.
That next level is on its way in the form of mandatory ballast water treatment, for the 12,000 saltwater ships that enter all U.S. waters annually.
Federal agencies are set to finalize new regulations this year requiring saltwater ships to treat their ballast with some sort of on-board system using chemicals, ultraviolet light, filters or other technology to kill any foreign creatures in the tanks.
Starting with the oceangoing "salty" vessels and eventually expanding to lake freighters, these measures should provide additional insurance against invasive species that imperil the economy and ecology of the Great Lakes Basin.