New crayfish taking over Manitoba Lake

They're aggressive, have large claws and are taking over a Manitoba lake: Provincial biologists are asking the public to keep an eye out for an invasive new species of crayfish. The rusty crayfish, native to the Ohio River basin, have been found for the first time in Falcon Lake in Whiteshell Provincial Park, in southeastern Manitoba. Provincial biologists are asking the public to do its part to keep the species from spreading to other lakes and rivers in the province, saying its presence could be devastating. "They're about the same size, marginally larger, than our own native species, but their claws are significantly larger," Water Stewardship spokeswoman Wendy Rally told CBC News on Wednesday. "They're much more aggressive. They eat about twice as much as our native species." Ralley said the area of Falcon Lake where the rusty crayfish were found no longer has any native species left. "They will out-compete our native species by occupying their hiding spots. They'll actually physically remove our native species out of the prime hiding spots, and that makes our native species more apt to be preyed upon by predatory fish." The new crayfish could also "severely reduce" lake and stream vegetation, leaving native fish without any cover, spawning habitat or food. The invasive crayfish were likely brought into the province by a fisher intending to use it as bait, Ralley said. Past experience in other areas of North America indicates once the rusty crayfish are established, they are impossible to eradicate, officials said, so they've asked for the public's help in avoiding their transfer to other lakes and rivers. Boaters and fishers should keep their eyes peeled for crayfish, which have brown bodies with rusty-colored patches on each side and claws with black bands near the tips. To avoid transferring them to another lake, Manitobans are asked to never collect crayfish for any purpose, including consumption, bait or aquarium use, and to remove mud, vegetation and bilge from boats before transporting them. Since May 1, it has been illegal to possess any type of crayfish in Manitoba.

 Source: http://www.cbc.ca/canada/manitoba/story/2007/08/23/rusty-crayfish.html

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