A Nutria caught in a trap placed by biologists with the California Department of Fish and Wildlife, at the China Island state wildlife area near Gustine, Ca. on Wed. May 2, 2018. (Photo By Michael Macor/The San Francisco Chronicle via Getty Images)
LOS ANGELES - A landmark genomic study by the California Department of Fish and Wildlife (CDFW) has confirmed that the destructive nutria population currently spreading through the Central Valley did not survive undetected from the 1970s, but was likely intentionally reintroduced from Oregon.
What we know:
Scientists with the CDFW’s Wildlife Genetics Research Unit compared the DNA of California's current nutria with historical specimens from museums, universities, and even a taxidermy mount from a county office.
The research confirmed that the modern invasion is a "recent reintroduction" rather than a survival of the original fur-trade era populations.
Since 2017, the Nutria Eradication Program has removed 7,841 animals.
SUGGESTED: 6th rattlesnake bite in 30 days triggers safety warning in Ventura County
The species is currently classified as an "A-rated pest" because their burrowing destroys irrigation systems and their feeding habits devastate native marsh ecosystems.
The state is currently spending $5 million per year to manage the spread across hundreds of thousands of acres in the Sacramento-San Joaquin Delta and Central Valley.
What we don't know:
While the genomic data points to a human-assisted move from Oregon, the "reasoning" behind the illegal reintroduction is unknown.
SUGGESTED: Coyote that attacked toddler in Carson caught, euthanized
Experts can only speculate whether the rodents were released by private landowners for misguided vegetation control, kept by enthusiasts who liked the species, or released as a form of "environmental sabotage" intended to cause infrastructure damage.
What they're saying:
"Given where nutria were rediscovered in California, it is nearly impossible that they could have migrated there on their own," said Michael Buchalski, CDFW Wildlife Genetics Research Lead. "It’s too far of a distance and we don’t find any nutria in the areas in between. That makes human introduction the most likely scenario."
Valerie Cook, Nutria Eradication Program Manager, noted the findings validate long-held suspicions: "This study supports our long-held belief that the current invasion is the result of reintroduction rather than explosive growth of a remnant, undetected population."
SUGGESTED: CAUGHT ON CAMERA: Fisherman reels in 7-foot great white shark at Hermosa Beach Pier
What's next:
The CDFW will continue its aggressive trapping and detection strategy using motion-detection cameras and scat-detection dogs. Agricultural officials are also maintaining biosecurity inspections at entry points to prevent further illegal importations.
What you can do:
The public is urged to report any sightings of the large, orange-toothed rodents to the CDFW.
Because the transportation of nutria is prohibited by Fish and Game Code section 2118, residents should never attempt to move or relocate the animals themselves.
The Source: This report is based on a five-year genomic study conducted by the California Department of Fish and Wildlife’s Wildlife Genetics Research Unit in partnership with the USDA and the California Department of Water Resources.