Great Lakes invasive species studied

WASHINGTON, May 23 (UPI) -- The longstanding problem of various invasive species entering the Great Lakes via the St. Lawrence Seaway is now gaining attention from scientists.

The National Academy of Sciences convened a committee of transportation, economic and environmental experts Tuesday to explore ways to halt the flow of unwanted creatures into the world's largest freshwater system, while not interfering with international shipping in the area, the Milwaukee Journal-Sentinel reported.

Most invaders enter the lakes in contaminated ballast water used to stabilize ships. Such ballast is often taken on at one port and dumped at another, the Journal-Sentinel said.

At least 180 invasive species have, so far, entered the Great Lakes and a new one is discovered about every six and a half months, the newspaper said, noting the world's ocean shipping industry is trying to develop technology that will decontaminate ships' ballast water tanks.

Conservationists are reportedly beginning to question the value of overseas shipping to the Great Lakes, given the ecological problems it is causing.