"Based on the size and morphology of both Didemnum vexillum populations, we think they probably became established at roughly the same time about two years ago," Chan said. "The origin is still unclear and we have to be careful not to point fingers."
Chan said tunicate infestation can be introduced through a variety of vectors, including boats and aquaculture.
The Oregon Department of Fish and Wildlife is in the final stage of a risk assessment. When completed, recommendations will be made and an action plan developed.
"We're reviewing the literature for successful eradication projects on rocky outcrops or jetties, but we're not finding a lot," said Rick Boatner, ODFW's aquatic invasive species coordinator. "This is new ground for Oregon, and we'll have to be creative with our solutions."
Chan and ODFW officials say the best approach may be to establish a pilot "adaptive learning" control and monitoring project within the triangle in early summer before water temperatures warm enough to trigger the tunicates' reproductive cycle. Support for such a project may come through an "Invasive Species Control" fund established by the Oregon Legislature and signed by Gov. Ted Kulongoski in 2009. The Oregon Invasive Species Council must declare an emergency to activate this account, Chan said.
Possible methods of eradication include "smothering" the colonies, physically removing them and vacuuming all traces, or applying a vinegar and/or bleach solution. The Oregon Invasive Species Council will hold workshops in affected coastal communities later this spring to inform the public about tunicates before the pilot control project begins.
Vallorie Hodges, dive safety officer for the Oregon Coast Aquarium, said the Winchester Bay tunicates resembled certain species of soft corals.
|Contact: Sam Chan|
Oregon State University