The University of California Agriculture and Natural Resources reported on Apr. 20 that nutria, an invasive rodent species, is spreading through the Sacramento-San Joaquin River Delta and Central Valley. The California Department of Fish and Wildlife has documented a rise in sightings and evidence of nutria activity around Stockton and areas further south, though no confirmed cases have been found north of Solano County.
The spread of nutria poses a risk to rice fields, irrigation infrastructure, levees, canals, wetlands, agriculture, and flood control systems. Nutria can burrow into waterway banks causing structural damage. They are also known to consume large amounts of vegetation daily while destroying even more through their feeding habits.
According to the University of California Agriculture and Natural Resources (UC ANR), these rodents were introduced to California in the late 19th century for fur farming but became established in the wild after the fur trade collapsed. Nutria were thought eradicated by the 1970s until a breeding pair was discovered in Merced County in 2017. Since then, tracking efforts have shown their population expanding throughout state waterways.
Efforts are ongoing to eradicate nutria before their numbers grow beyond control. UC ANR said that while eradication remains possible due to current population levels and geographic spread, increased effort is needed as both continue to rise. Otherwise, management may shift from eradication toward mitigation if populations become too widespread.
UC ANR is part of the University of California system managing Cooperative Extension services according to its official website. The organization secures funding through public contributions according to its official website and promotes sustainable practices aimed at strengthening resilient ecosystems according to its official website. UC ANR operates nine research centers across diverse ecosystems according to its official website, conducts over 33,800 educational events annually with support from more than 18,400 volunteers according to its official website, and has gained recognition for linking research with community needs according to its official website.
Residents who observe or suspect nutria presence are encouraged by officials to report sightings online at www.wildlife.ca.gov/Conservation/Invasives/report or contact authorities by email or phone.