Diet change for more sustainable finfish aquaculture
As the cost of fish oil continues to rise, Australian aquaculture operators are looking for safe and more sustainable sources for healthy formulated feed in order to expand commercial production of the popular yellowtail kingfish.
A South Australian study led by Flinders University, in the journal Aquaculture, assessed the use of substitutes canola oil and poultry oil in farmed kingfish production.
"Reducing the use of wild-caught sardines and other small fish to sustain farmed fish鈥攖o produce more farmed fish for human consumption鈥攚ill help maintain our oceans and fishery food chains," says Associate Professor James Harris, from the College of Science and Engineering at Flinders University.
As well as demand for seafood in a healthy diet, fish oil is also used in terrestrial animal feeds, with an estimated 460% of current production levels required by 2030 also driving up the commodity costs for aquaculture industries.
"We can't keep catching loads of small fish to feed to larger fish we are growing, so we are increasingly looking to reduce fish oil in their diets."
Fish oils have large concentrations of long-chain omega 3 polyunsaturated fatty acids which are essential for cultured carnivorous finfish to sustain optimal growth and health.
The Flinders experts, with colleagues from Primary Industries and Regions SA (PIRSA) research division SARDI and the University of Adelaide School of Animal and Veterinary Sciences, undertook the study on locally grown kingfish.
"We found that both oil from canola plants and oil from poultry could be effectively used, although there were some potentially adverse changes seen in the kingfish livers," says Associate Professor Harris.
"These changes give us a chance to investigate further the major role in kingfish fat metabolism to continue looking to manipulate formulated feed to produce these popular fish, which also are farmed in Japan, Europe and the Americas."
Previous aquafeed studies have also used soybean oil and swine, bovine or ovine fats as fatty acid substitutes or supplements, with the goal of achieving optimum growth and lipid metabolism as well as palatability of alternative feeds.
More information: Benjamin H. Crowe et al, Liver structure and function in yellowtail kingfish, Seriola lalandi, in response to alternative oils in feed, Aquaculture (2024).
Provided by Flinders University
