Invasive crayfish claw their way across America and take over US lakes
Wildlife experts are scrambling to keep the growing populations in check as the crayfish alter shorelines and aquatic habitats.
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THE TAKEAWAY
- Invasive crayfish populations are surging across the U.S.
- The animal is threatening native species, aquatic vegetation and habitats.
- Millions of crayfish are lurking in Lake Tahoe, Lake of the Woods, Crater Lake, Lake Mead and Lake Michigan.
- Officials want to regulate their use as fishing bait and allow people to trap and remove them.
The end of summer is just a few weeks away, and millions of people are heading to lakes across the country to soak up the last days of the season.
But beneath the beauty of some of these waters, an invasive species is quietly taking over.
Across the U.S., invasive crayfish — also known as crawfish — populations are surging, threatening native species, aquatic vegetation and habitats.
A red swamp crayfish (Procambarus clarkii) is pictured near a lake.
(ODD ANDERSEN/AFP via Getty Images / Getty Images)
In Lake Tahoe, for example, the crayfish population has exploded in recent decades. Estimates show the number of invasive signal crayfish has grown from roughly 56 million in the 1960s to between 240 million and 280 million today.
Now, wildlife experts are scrambling to keep the growing populations in check as crayfish alter shorelines and aquatic habitats.
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And Lake Tahoe isn't alone. According to WorldAtlas, invasive crayfish have been reported in several other major lakes, including Lake of the Woods, Crater Lake, Lake Mead and Lake Michigan.
There are several species of invasive crayfish found across the U.S., including rusty crayfish and signal crayfish. While these species are native to certain parts of the country, they can become highly destructive when introduced into ecosystems where they don't naturally occur.
A crayfish is on a dry riverbed.
(YOHAN BONNET/AFP via Getty Images / Getty Images)
Their spread has been linked to human activity, including the release of unused fishing bait, aquarium dumping, aquaculture and intentional introductions.
In Lake Tahoe, signal crayfish were introduced in the late 1800s, in part as a food source for stocked trout and for people to eat.
In the Great Lakes, rusty crayfish, which are native to the Ohio River Basin, have spread throughout much of the region, competing with native crayfish for food and shelter.
They are also known for consuming large amounts of aquatic vegetation. This can reduce habitat for fish and other wildlife.
A swamp crayfish crawls along the lakeshore.
(Andreas Arnold/picture alliance via Getty Images / Getty Images)
In Lake Tahoe, signal crayfish feed on aquatic plants, algae and other organisms, changing the lake's food web.
Scientists have been studying their role in changes to algae and native invertebrate communities.
The biggest concern is that invasive crayfish can act as predators, herbivores, competitors and ecosystem engineers. They can consume vegetation and other organisms, compete with native species and physically disturb the bottom of a lake.
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Across the country, lawmakers and state wildlife agencies are focusing primarily on prevention and population control. This includes restricting the possession and transportation of invasive crayfish, regulating their use as fishing bait and allowing targeted trapping and removal.
But in lakes where invasive crayfish are already firmly established, completely eradicating them is considered extremely difficult.