September 7, 2008

Pesticides May Reduce Invasive Fish

Federal researchers say they have discovered pesticides that can control voracious round gobies that have invaded the U.S. Great Lakes and Mississippi River.

U.S. Geological Survey biologists say two poisons have proved effective in targeting gobies, native to the Caspian Sea region, if the poisons are applied in a special formula that spreads them across only the bottom 2 inches of a lake or riverbed, the Milwaukee Journal Sentinel reports.

The scientists say the poisons' only practical use would be to control goby numbers in limited areas or to slow their spread into new bodies of water, the newspaper says.

"Inland lakes definitely would be a possibility," lead research author Theresa Schreier said.

The small fish -- which ferociously defend their spawning sites, squeezing out native species -- already have spread across the Great Lakes and into the Illinois River, scientists say.

The federal government hoped to halt their spread across the continent by building an electric fish barrier on the Chicago Sanitary and Ship Canal -- linking Lake Michigan with the Mississippi River system -- but the gobies made it past the canal before the barrier was completed.