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ASH MEADOWS NWR: Red Swamp Crayfish in the Desert
California-Nevada Offices , March 10, 2014
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Invasive Red Swamp Crayfish caught in a minnow trap at Ash Meadows NWR.
Invasive Red Swamp Crayfish caught in a minnow trap at Ash Meadows NWR. - Photo Credit: Cindy Sandoval/USFWS
Minnow trap baited with cat food to catch invasive Red Swamp Crayfish at Point of Rocks.
Minnow trap baited with cat food to catch invasive Red Swamp Crayfish at Point of Rocks. - Photo Credit: Cindy Sandoval/USFWS
Endangered Ash Meadows Amargosa pupfish that lives along with invasive crayfish and frogs in many springs at Ash Meadows NWR.
Endangered Ash Meadows Amargosa pupfish that lives along with invasive crayfish and frogs in many springs at Ash Meadows NWR. - Photo Credit: Cindy Sandoval/USFWS

By Cindy Sandoval

For centuries people have introduced species to new habitats without thinking of the consequences to native species. One invasive species at Ash Meadows National Wildlife Refuge both competes with and feeds on native dace and pupfish. While the exact time of the Red Swamp Crayfish introduction is unknown, refuge staff is all too familiar with the consequences of crayfish in refuge springs and pools.

The Red Swamp Crayfish is native to the southeastern United States but the aggressive invertebrate can survive in a variety of habitats. The crayfish is not a new resident of Ash Meadows and reports of crayfish in spring pools date back decades. In fact the crayfish has become so well established that it is thought to be the cause of the extinction of the Ash Meadows poolfish.

In many cases once non-native species have become established in a new habitat its complete removal can be difficult if not impossible. There are few options for eradicating crayfish and for the pest to be eradicated every single individual crayfish needs to be removed. One Red Swamp Crayfish female can store sperm and potentially start a new population with 100-500 eggs. Crayfish are also excellent parents that carry their invasive offspring under their tail as eggs and juveniles until they are large enough to venture out. These young will reach full reproductive maturity in less than a year and continue the population.

Even in rare cases where a spring pool can be drained of water, crayfish can dig chimney like burrows up to three feet deep in the mud to survive times of low water and are capable of walking across land to new habitats. All of these factors add up to a strategy of containment over eradication at Ash Meadows NWR. Refuge staff set traps twice a week to capture and remove crayfish from native fish habitat.

The traps, which are minnow traps baited with cat food, also catch other invasive species like bullfrog tadpoles and mosquito fish. Refuge staff member Erin Bradshaw explains, “Since we can not remove the crayfish completely, we set these traps to control their population so that the native fish have a chance to compete.”

Fish habitat in the Nevada desert is limited and if native species like the Armargosa Warm Springs pupfish and Armargosa dace are out competed for food by the more aggressive crayfish the fish have no where else to go. So for now, the southern crayfish at Ash Meadows NWR are controlled to avoid future extinctions of rare desert fish species.

Cindy Sandoval is a public affairs specialist at the Pacific Southwest Regional Office in Sacramento, Calif.


Contact Info: Cynthia Sandoval, 916-978-6159, cynthia_d_sandoval@fws.gov



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