Sightings of the Chinese mitten crab outside of its native habitat make some scientists uneasy that it will turn into an invasive species. (Photo courtesy of the California Department of Fish and Game)
Biologists are asking people to keep their eyes peeled for another potential invader into the Great Lakes. A Chinese mitten crab was found in the St. Lawrence River last fall. The Great Lakes Radio Consortium’s David Sommerstein reports:
Transcript
Biologists are asking people to keep their eyes peeled for
another potential invader into the Great Lakes. A Chinese mitten
crab was found in the St. Lawrence River last fall. The Great Lakes
Radio Consortium’s David Sommerstein reports:
Scientists aren’t sounding the alarm yet. One Chinese mitten crab found near Quebec City doesn’t constitute an invasion. But if they reproduce, the critters could spread quickly.
David MacNeill is a fisheries specialist with New York Sea Grant. He says one was found in Lake Erie in the 1970s, but didn’t proliferate. The mitten crabs spawn in salt water, so they don’t really threaten the upper Great Lakes. But the St. Lawrence River may be better habitat. Regardless, MacNeill says the discovery highlights problems with foreign ships exchanging ballast water before they enter the Great Lakes system.
“Inside ballast tanks on ships, they’re like giant tidal mud flats. When you empty all the water out, there’s this large mud layer. Some of these organisms can burrow into the sediment which is what the mitten crabs do.”
In January, the Coast Guard conceded its ballast discharge rules don’t always work. It said it must find new ways to keep foreign invaders out of the Great Lakes.
For the Great Lakes Radio Consortium, I’m David Sommerstein.