AUSTRALIA - South Australian researchers are investigating dietary additives to reduce the effects of higher summer water temperatures and improve survival rates of farmed abalone.
Developing management techniques to reduce the effects of environmental and physiological changes, such as summer heat and spawning, are underpinning the greenlip abalone (Haliotis laevigata) industry’s prospects.
Some of the research findings have been presented by the South Australian Research and Development Institute (SARDI) at the World Aquaculture Adelaide 2014 conference in Adelaide.
Abalone aquaculture is a growing industry in South Australia, with leases for 30 sites issued for land-based and offshore abalone production.
SARDI Aquaculture science program leader Professor Xiaoxu Li said the conference was a good opportunity to share South Australia’s experiences with overseas counterparts whose onshore and offshore aquaculture systems might encounter similar challenges and opportunities, including competitive production techniques.
The research, funded by the Australian Seafood Cooperative Research Centre and Fisheries and Development Corporation, is supported by Marine Innovation Southern Australia (MISA), the Australian Abalone Growers’ Association and all three Australian commercial abalone feed manufacturers. Flinders University and the University of Adelaide are also collaborating on research projects.
Prof Li said a range of techniques were being investigated to support abalone aquaculture growth in Australia.
“We have been investigating abalone’s immunological responses to these stress factors and developing diets to boost abalone’s capacity to tolerate them.
“We can assist industry to reduce the risks through specifically formulated diets and improved management practices.”
Development of novel diet and feed technologies is part of the ongoing research effort.
High water temperature (more than 23oC), low dissolved oxygen levels and bacteria proliferation increases the risk in hotter months, said Associate Professor David Stone, who leads SARDI’s Aquaculture feed and nutrition research.
He is involved with supervising trials of novel feed additives, including grape seed extract and dried macroalgae (Ulva lactuca), to increase survival rates during hot summer conditions.
“This study aims to use these products, which contain antioxidative and bioactive compounds, to increase survival in abalone at high water temperatures (26oC),” he said.
“Dietary intervention – including live macroalgae – proved to have a positive effect, so we are encouraged with the results so far.”
Another project led by A/Prof Stone is looking at better matching dietary protein levels with abalone type (greenlip and hybrid abalone) to improve performances – including growth and survival rates – during the seasonal temperature fluctuations.
“Instead of a single diet feeding strategy, commercial producers could look at a range of options to improve productivity,” A/Prof Stone said.
“We have developed a model for testing nutritional variations in adult and juvenile abalone in different water temperatures.
“The results from this model have promoted the adoption of some of these developments in land-based farms in Southern Australia.”
SARDI is the Government of South Australia’s primary industries research institute and is a division of Primary Industries and Regions South Australia (PIRSA).
MISA is a partnership of the Government of SA, SARDI, Flinders University, University of Adelaide, South Australian Museum and the seafood industry.
TheFishSite News Desk