Seriola spp. are susceptible to a variety of viral, bacterial and parasitic diseases. In Japan, where considerable culture of these fish occurs (including S. dumerili, S. lalandi and S. quinqueradiata), several pathogens and parasites are responsible for serious production inefficiencies. Monogenean (flatworm) parasites are one of the most serious problems for the yellowtail industry and may increase production costs by over 20% (Ernst et al. 2002). In Australia, monogeneans have become a serious risk to sustainable development of the emerging kingfish industry (S. lalandi) in Spencer Gulf. Without efficient, effective and environmentally aware parasite management strategies, competitive and sustainable production will be impossible. The need for improved parasite management is recognised by industry in Australia and Japan and by the Australian Government who have jointly invested over $1 million through a 3-year Australian Research Council Linkage Project (“Kingfish/Yellowtail Parasite Management Project”) to develop integrated management strategies for the aquaculture of Seriola spp. (see Synergies below). This research project, however, has no funding to investigate the important issue of interactions between wild and cultured fish stocks. This topic is of critical concern to sea-cage aquaculture of kingfish as it has been for sea-cage aquaculture of salmonids (Anonymous 1997).
There is currently a lack of scientific information on the interactions between wild and cultured fish directly applicable to the waters of South Australia in particular, and Australia in general, on which to base sound aquatic animal health policy, licence conditions and operating standards to safeguard both the wild and cultured fish populations. There is an immediate need for research in this area to allow PIRSA Aquaculture to develop effective policy and zone management, and to provide a framework for the development of Commonwealth principles of best practice and environmental management.
Whilst Seriola spp. are considered an appropriate starting point, it is envisaged that the broad principles of policy and standards derived from the research may be applied to the marine finfish aquaculture industry as a whole in Australia. With this in mind, a three-year project is considered necessary to study the yellowtail kingfish (Seriola lalandi) sector of the marine finfish net pen aquaculture industry, specifically to investigate the population dynamics and parasite interactions of skin flukes (Benedenia seriolae) and gill flukes (Zeuxapta seriolae) on cultured and wild fish. A second requirement is to study the effects on the wild population of any escapees from culture facilities. The yellowtail kingfish sector is again an appropriate model due to the close association of the cultured and wild fish in the Spencer Gulf.
Final report
This project greatly contributed to an increased understanding of parasite fauna of yellowtail kingfish in Australian waters. This baseline information is critical to understanding potential parasite interactions between wild and farmed kingfish. Our risk assessment enables consideration of parasite species of potential threat to the emerging industry. We found batch marking hatchery fish with fluorescent dye may be the most practical and inexpensive method to discriminate wild and farmed fish. We also provide the first data on wild kingfish migrations in Spencer Gulf, demonstrating that there may be heightened interactions between wild and farmed fish in Fitzgerald Bay in summer.
This project provided training to several researchers, including one PhD student in the area of aquatic animal health and one Honours student in the area of otolith chemistry. We indicate appropriate methods to enable better management practices in the kingfish industry which will help improve the viability of kingfish aquaculture in Australia in the future.
Keywords: Seriola, aquaculture, parasites, otolith chemistry, conventional tagging programme.
