Diseases in Tuna Aquaculture

Successful health management of farmed fish is essential for sustainable aquaculture. The level of potential control of pathogens is related to the type of aquaculture system. Cage culture offers little control over waterborne pathogens and may contribute to free living organisms becoming parasitic (Nowak, 2007). Furthermore, stress level is harder to control in cage culture, in particular stress due to confinement or the presence of predators or extreme or unfavorable weather conditions. A disease outbreak is a result of the interaction between host, pathogen, and environment. In addition to the limited control over the presence of pathogens, cage culture may contribute to stress of the host and as a result immunosuppression. Risk of the outbreaks of the diseases can be assessed on the basis of the presence of the pathogens and parasites in the cage farming environment. This review focuses on three species of tuna: Atlantic bluefio tuna (ABFT), Pacific bluefin tuna (PBFT), and southern bluefin tuna (SBFT), all of which are ranched or farmed in cage culture. Different parasites emerged as health risks for ranched SBFT (Nowak, 2004) and PBFT (Nowak et al., 2006). Some of these parasitic infections have been associated with mortalities and reduced production (Polinski et al., 2013).