Several years ago, a new rickettsia-like organism (RLO) was observed in the tissues of farmed abalone. Since then, transmission electron microscopy has show that the “new” parasite is probably just the original withering syndrome rickettsia-like organism infected with a phage hyperparasite. With Sea Grant support, scientists have identified a set of potential phage genes and are in the process of testing PCR primers that can be used to fully characterize the organism and document its geographical distribution in both wild and farmed animals, and in seawater. Withering syndrome is a lethal, contagious water-borne abalone disease that seems to be triggered by El Niño, or El Niño-like, coastal warming. In recent years, outbreaks have become less frequent and severe, and it is not known whether this is due to cooler water temperatures or because the pathogen now includes the phage parasite, which appears to confer disease protection. As part of this project, scientists will test the RLO’s protective value, and its link to water temperatures, as well as efficacies of various antibiotic therapies. Five of the state’s eight abalone species are categorized as “species of concern” or are protected by the Endangered Species Act. Results from this project will be shared with NOAA Fisheries managers charged with developing recovery plans for the abalone, and with abalone farmers vulnerable to withering syndrome outbreaks. The Abalone Farm in Central California, the state’s largest abalone producer, is a collaborator on the project.