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Reign of invasive rusty crayfish may be ending; Wisconsin lakes rejoice

Danny Szydlowski sampling for aquatic snails

URBANA, Ill. – Just how hard should natural resource managers fight invasive species after they establish? A new University of Illinois study suggests some invaders – even highly successful ones – can die off naturally, leaving native communities to rebound with minimal management effort.  

That’s the case for rusty crayfish in some Northern Wisconsin lakes. According to the 33-year study, many lakes in the region have seen steady declines of the crustacean, with a handful of lakes falling to nearly zero. Whether they’ve destroyed their own habitat or died off due to disease, the results are clear: when rusty crayfish decline, water plants and snails bounce back.

“This is one of the organisms that put invasive species on the map for freshwaters in the U.S. and North America. We've been studying the invasion and impacts of rusty crayfish since the 1970s, before zebra mussels and other major freshwater invasive species were introduced. This is really the landmark species that got managers and policy makers to recognize the accidental introduction of a crayfish could rewire an entire lake's food web or cause declines of harvested fish populations.

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