Asian Kelp (Undaria pinnatifida)

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    The aquatic invasive species Asian Kelp, also known as Undaria pinnatifida, has been found in the San Francisco Bay and Pillar Point Harbor (Half Moon Bay).

    This invader has been in Southern California since the year 2000. It has spread into the harbors of Channel Island, Long Beach, Los Angeles, Monterey, Oceanside, Pt. Hueneme, Santa Barbara and Santa Catalina, and into the bays of Mission and San Diego.

    Asian Kelp can grow on ship hulls, nets fishing gear, moorings, ropes, docks and other marine structures. Although it can spread short distances on its own, invasions have been linked to boating traffic. Because of its prolific growth and large sizeit can quickly foul natural and man-made structures, causing economic and ecological damage. It also competes for light and space with native populations of marine algae, plants and animals, drastically affecting native ecosystems.

    Currently, scientists from the Monterey Bay National Marine Sanctuary, the California State Lands Commission and the US Department of Agriculture are working with the Smithsonian Environmental Research Center (SERC) to carefully delineate the boundaries of the current populations while engaged in a manual removal effort.

    • Report any observations of this kelp to SERC.
    • Identify the exact location.
    • If possible, remove the kelp and send photographs to SERC to confirm identity.
    • Store the sample in a plastic bag in a cooler or refrigerator until its identity has been confirmed.
    • Avoid moving contaminated (infected) vessels or equipment.
    • Clean boats before moving or returning home. Specifically:
      • Clean boat hull, underwater running gear, and internal seawater systems before traveling beyond your home region, especially if visiting major ports, international waters, islands or events with boats from many places.
      • Clean the boat again before moving to another region or returning home.
      • If boat is heavily fouled after such trips, haul it for cleaning upon arrival and contain the fouling growth.
      • Drain livewells, bait tanks and bilge water before traveling and before returning.
      • Do not throw the kelp back in the water.

    For more information or to report an observation, contact the Smithsonian Environmental Research Center at or (415) 435-7128. You may also visit

    Additional information on how to prevent the spread of Asian Kelp and other saltwater aquatic invasive species may be found on the University of California Cooperative Extension - Sea Grant Extension Program