PCR- based detection and quantification of Renibacterium salmoninarum in ovarian fluid of returning chum salmon Oncorhynchus keta and masu salmon O. masou in Hokkaido, Japan

Abstract

Renibacterium salmoninarum was detected in ovarian fluid of returning salmonids using nested PCR; chum salmon from seven rivers (925 samples) and masu salmon from three rivers (309 samples) in Hokkaido in 2015 and 2016. Real-time PCR was also performed for the samples in 2016. In chum salmon prevalence of R. salmoninarum genome was 0%-90% in 2015 and 12%-98% in 2016. In masu salmon the prevalence was 0% in 2015 and 50%-84% in 2016. In 2016, the prevalence had risen in the samples in eight of ten rivers. The numbers of R. salmoninarum genome were estimated to be 1.0 × 101- 8.0 × 102 copies/μL of ovarian fluid.