Undaria is a large, golden-brown kelp native to Japan, Korea, and China. It doesn’t travel fast or far on its own, but it is a skilled hitchhiker. As ship and boat traffic has increased around the world, it has caught rides to distant shores on boat hulls or in ballast water. If conditions are right in the new harbors it reaches—and a wide range of conditions will do—it will spread. Before long it can cling to new boat hulls, clog docks, smother fishing gear, disrupt marine farming, or even alter marine ecosystems. Such impacts have earned it a spot among the world’s 100 worst invasive species.
Undaria was first found in California in 2000 in Long Beach Harbor. Since then it has been inadvertently carried by boat to other harbors up and down the California coast. It hitchhiked to Catalina Island and Channel Islands Harbor early on. In 2008, it was discovered in Ventura Harbor, the mainland home of Channel Islands National Park. Soon after, the park created outreach materials such as dockside posters to educate local boaters on how to recognize and prevent the spread of this invader. The park’s islands seemed to remain infestation-free. Then, in June 2016 Kelp Forest Monitoring Program (KFMP) biologists discovered the invader during their annual survey of a monitoring site on the north side of West Anacapa Island. An even more recent Undaria discovery took place at San Clemente Island to the south of the park this June.
