Detection of bluefin tuna blood flukes (Cardicola spp.) from wild juvenile Pacific bluefin tuna Thunnus orientalis caught for aquaculture

Abstract

Blood fluke infection is one of the main causes of mortality in cultured juvenile Pacific bluefin tuna Thunnus orientalis (PBT) in Japan. We investigated 532 wild juvenile PBT of four different fish groups caught for tuna culture seed stock from off the Goto Islands, Nagasaki, Japan between 2011 and 2014, to determine whether they were infected with blood flukes. We detected the blood flukes, Cardicola orientalis and C. opisthorchis, from all four fish groups investigated. From this, it is suggested that bluefin tuna blood flukes are brought into tuna farms with the infected wild seed stock.