First isolation of virulent Tenacibaculum maritimum strains from diseased orbicular batfish (Platax orbicularis) farmed in Tahiti Island

Abstract

The orbicular batfish (Platax orbicularis), also called Paraha peue in Tahitian, is the most important marine fish species reared in French Polynesia. Sudden and widespread outbreaks of severe white-patch disease have occurred since 2011 in batfish farms one to three weeks after the transfer of juveniles from bio-secured hatcheries to lagoon cages. With cumulative mortality ranging from 20 to 90%, the sustainability of aquaculture of this species is severely threatened. In this study, we describe for the first time the isolation from diseased batfish of several strains belonging to the species Tenacibaculum maritimum, a major pathogen of many marine fish species. Histopathological analysis, an experimental bath challenge and a field monitoring study showed that T. maritimum is associated with white-patch disease. Moreover, molecular and serological analyses performed on representative strains revealed some degree of genetic diversity among the isolates, a finding of primary importance for epidemiological studies and for the development of management and control strategies such as vaccination.