A survey of blood fluke, Cardicola forsteri, infection in ranched southern bluefin tuna, Thunnus maccoyii, was undertaken over three farming seasons, from March 2004 to September 2006. Analyses of covariance and logistic regression were used to explore the effects of company, year, season, time in culture, and condition index on intensity, abundance and prevalence of blood fluke infection. Average prevalence of blood fluke infection was 62.64% over the period of the survey. Average intensity was 6.20 (± 0.57) fluke per infected host and the average abundance was 3.70 (± 0.57) fluke per host. Year did not influence mean intensity or abundance although a significant decrease in prevalence in 2005 was evident. Tuna harvested in winter had a significantly greater abundance and prevalence of blood fluke than the tuna harvested in autumn. No effect of intensity or abundance of infection was observed on the condition of the infected tuna. A universal factor in explaining variation in C. forsteri intensity, abundance and prevalence was company. Differences in infection levels between tuna from different companies may be related to differences in husbandry measures employed on each farm, or due to different average sizes of tuna farmed by each of the companies, or due to the location of the operations.

Item Type:	Refereed Article
Keywords:	blood fluke, Southern bluefin tuna, aquaculture, epidemiology
Research Division:	Agricultural and Veterinary Sciences
Research Group:	Fisheries Sciences
Research Field:	Aquaculture
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Fisheries - Aquaculture
Objective Field:	Aquaculture Tuna
Author:	Aiken, HM (Mr Hamish Aiken)
Author:	Hayward, CJ (Dr Craig Hayward)
Author:	Nowak, BF (Professor Barbara Nowak)
ID Code:	100446
Year Published:	2015
Web of Science® Times Cited:	4
Deposited By:	IMAS Research and Education Centre
Deposited On:	2015-05-17
Last Modified:	2016-04-18
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