Two Species of Cardicola (Trematoda: Aporocotylidae) found in southern bluefin tuna Thunnus maccoyii Ranched in South Australia

Abstract

We determined the identity of an aporocotylid blood fluke discovered in the gills of southern bluefin tuna Thunnus maccoyii ranched in Australia.Both morphological and molecular data indicate the parasite is Cardicola orientalis, reported previously only from Pacific bluefin tuna T. orientalis in Japan.Over 70 C. orientalis adults were retrieved from a single gill arch of an infected southern bluefin tuna and numerous eggs were observed in the gill filaments suggesting possible pathology to the host. In addition, we obtained new information on morphological characteristics and molecular sequences of C. forsteri infecting the heart of T. maccoyii.This is the first report of C. orientalis in T. mccoyii, which may have a significant impact on the ranching industry of southern bluefin tuna and warrants further investigation. © 2013 The Japanese Society of Fish Pathology.