California Sea Grant College Program

The withering syndrome bacterium Candidatus Xenohaliotis californiensis was believed to be confined to warmer ocean waters south of San Francisco. A survey of abalone beds, conducted by fish pathologist Dr. Carolyn Friedman, however, has revealed that the bacterium has spread to two isolated locations in colder northern waters. Her work suggests that human activity—aquaculture practices or abalone “outplantings”—may have contributed to the spread of the bacterium.