CINCINNATI (TDB) -- Shark music, please. State officials in Maryland sound quite concerned about the recent discovery of rusty crayfish in the Susquehanna River watershed. The aggressive natives from the Ohio River Valley turned up this summer, prompting dire warnings about threats of devastation to the freshwater ecosystems of states south of the Mason-Dixon line. There are even reports from Minnesota -- where the rustys have already rambled -- that they like to pinch swimmers and have frightened people away from beaches.
In recent years, the invertebrate invaders from Ohio have successfully expanded their range into 15 states.
The crayfish -- which can grow up to five inches long -- have also been found in Canada and Minnesota, where they have colonized 11 counties and 31 lakes and streams, according to officials with the University of Minnesota's Sea Grant. Maryland's Department of Natural Resources sounds like it is in panic mode.
"Invasions of this species have resulted in the loss of native crayfish. They are known to feed upon fish eggs and can reduce the quality of habitat available to many fishes and other invertebrates. Rusty crayfish also feed on freshwater mussels, 70% of which are threatened or endangered. . . Rusty crayfish cannot legally be imported, transported, purchased, possessed live, propagated, sold or released into Maryland water."
Minnesota says they are probably there to stay, and that the only thing to do is to eat the rustys for food, or use them for fishing bait. They live in lakes, ponds and streams and like to hide under rocks and debris. They don't dig burrows. And they don't back down in a fight. If a fish approaches, they raise their claws in a defensive posture. Many other crayfish species just try to swim away. The rustys also scare the beejeesus out of some people, say researchers in Minnesota:
"Cabin owners on heavily-infested Wisconsin and Minnesota lakes have even stopped swimming because large number of rusty crayfish occupy their favorite swimming area throughout the day. They fear stepping on them and getting pinched by the large clawed rustys. Other crayfish species, even if abundant, are usually less conspicuous during daylight hours."
Biologists think that anglers probably carried the species in their bait buckets from native territory into the newly invaded regions. Also, schoolchildren and teachers may have inadvertantly set them loose in unfamiliar terrain, where the crayfish from the Rust Belt managed to get a toehold, then prosper. Officials say schools used the crayfish in classes, or kept them in aquariums, then dumped them into creeks or lakes.