From paddocks to ponds: CQUniversity research explores new approach to fish parasite management
A forecasting method long used by crop farmers to predict pest outbreaks could help shape the future of parasite management in aquaculture, according to new research led by CQUniversity in collaboration with Tropical Australian Academic Health Centre (James Cook University), the South African government: Directorate of Aquaculture Innovation and Technology, and Department of Forestry, Fisheries and Environment.
Published in the international journal Veterinary Parasitology, the study investigated whether a temperature-based forecasting approach commonly used in agriculture could be adapted to predict the development of one of the world's most damaging marine fish parasites, Amyloodinium ocellatum, often called marine velvet disease.
The research was led by Dr David Vaughan from CQUniversity's Coastal Marine Ecosystems Research Centre (CMERC), which conducts research supporting the sustainable management and development of marine and coastal industries.
Rather than focusing on a new treatment, the study explored whether temperature and accumulated heat could be used to predict when parasites are most likely to reach infectious stages in their life cycle.
The concept is already widely used in agriculture, where growers use temperature data to anticipate the emergence of insect pests and better plan management strategies.
Dr Vaughan wanted to know whether the same thinking could help address disease challenges in aquaculture.
"Historically, aquaculture has largely relied on responding to disease once signs become visible in fish stocks," Dr Vaughan said.
"We wanted to investigate whether the same forecasting principles successfully used in agriculture could be applied to aquatic parasites and whether that information could help researchers and producers better understand when key stages of a parasite's life cycle are likely to occur."
The study found a strong relationship between water temperature and parasite development, demonstrating that a temperature-based model could potentially be used to estimate when infectious stages emerge.
Importantly, the research also found a South African strain of Amyloodinium ocellatum was capable of completing its life cycle at temperatures as low as 15°C, lower than previous studies had suggested.
While the findings are specific to a single strain collected in South Africa, Dr Vaughan said the broader significance lies in the modelling approach itself.
"The model is transferable, but the data is not," he said.
"Researchers elsewhere cannot simply apply these numbers to their own systems, but they can use the same approach to generate local data and test whether the methodology works for different parasites, environments and aquaculture species."
Aquaculture now produces more seafood globally than wild-capture fisheries, making effective disease management an increasingly important focus for researchers and industry.
Dr Vaughan said the study was designed as a proof of concept and an invitation for further investigation.
"This research is about encouraging a different way of thinking," he said.
"We've shown that an established agricultural concept can be adapted to an aquaculture parasite. The next step is for researchers around the world to test the framework under real production conditions and determine where it may be useful."
The publication also brings to fruition a dataset collected nearly two decades ago while Dr Vaughan was working in industry.
Using only two infected fish available at the time, researchers collected observations every four hours, around the clock, for 14 consecutive days before spending years refining the statistical analysis needed to unlock the data's full value.
"We knew the data were important, but it took time to develop the analytical expertise needed to do the study justice," Dr Vaughan said.
"Publishing it now puts the idea into the scientific literature where it can be tested, challenged and improved by others."
For the team at CMERC, the study reflects the centre's focus on exploring practical solutions to emerging challenges facing marine industries and aquatic animal health.
