Invasive Species Program

What does the Invasive Species Program do?

The mission of the Invasive Species Program is to reduce the negative effects of non-native invasive species on the wildlands and waterways of California. We are involved in efforts to prevent the introduction of these species into the state, detect and respond to introductions when they occur, and prevent the spread of invasive species that have become established. Our projects address problems with introduced animals and plants, both terrestrial and aquatic. More fundamentally, we try to identify and address the ways by which the species are introduced, typically inadvertently, by human activities. Studies show that preventing introductions is the most effective and cost-efficient way to manage invasive species. We conduct our work in coordination with other government agencies and non-governmental organizations.

What makes a species “invasive,” how they got here, and why they are a problem.

What's new in the Program?

2020 California Invasive Species Action Week: June 6-14

The 7th annual California Invasive Species Action Week will be June 6-14, 2020. Visit the CISAW page for links to activities you can do online or in your neighborhood. 

Youth Art Contest

The 2020 theme was "Be a Habitat Hero! Stop Invasive Species." Youths in grades 2 through 12 are eligible to enter the annual contest, and all types of media are welcome and encouraged! Winners will be announced on CDFW social media during Action Week. Visit the Art Contest web page for full details or contact

Invasive Nutria Discovered in California

In March 2017, a pregnant, female nutria (Myocastor coypus) was discovered in Merced County. Native to South America, nutria are large, semi-aquatic rodents that are considered one of the world's worst invasive species. Once introduced, nutria rapidly expand in both population size and geographic distribution. Female nutria reach sexual maturity as early as 4 months of age and producing their first litter by 8-9 months of age. They breed year-round, producing up to 3 litters per 13 months, with 2-13 young per litter. Nutria live in social groups consisting of a dominant male, several reproducing females, and juveniles, with maturing males driven out and dispersing up to 50 miles. Visit CDFW's Nutria Incident web page to learn more about the current status of this infestation, what is being done about it, and how you can help.

Quagga / Zebra Mussel Regulations

On February 10, 2016, the California Office of Administrative Law issued a Notice of Approval of Regulatory Action for CDFW's proposed dreissenid mussel regulations. These new regulations, Title 14, sections 672, 672.1, and 672.2, developed under the authority of Fish and Game Code sections 702, 2301, and 2302, became effective April 1, 2016. Visit the Quagga / Zebra Mussel Management page for more information.

Aquatic Invasive Species Identification Poster

The Invasive Species Program has developed an outreach poster to aid in the identification of six invasive species that threaten California's freshwater environments. link opens in new windowView the poster (PDF), or look for it on display in a CDFW office or hatchery. Would you like a copy of the poster to display? Contact us at to request one.