Samples from the last farms de-stocked in November 2017 were examined using histology tools and PCR. ostreae and protect uninfected wild populations.Īt that time Cawthron’s research turned towards understanding the effect of B. This triggered the closure of all NZ flat oyster farms to limit the spread of B. In 2015 the exotic parasite Bonamia ostreae was detected for the first time in NZ and the Southern Hemisphere. New Zealand’s native flat oyster Ostrea chilensis forms the basis of the iconic wild Bluff Oyster fishery, and until 2017, a small but growing aquaculture industry. “The main implication from this study for oyster farmers and hatcheries is that if you have a bad batch of microalgae with problematic bacteria, overfeeding larvae will make the problem worse, and reduced feeding could mitigate the impact.” “Globally, Pacific oyster production has a value estimated at US$ 1.24 billion a year, and hatchery production of oyster spat is really the only sustainable way to supply seed, so we want to understand and prevent hatchery mortality events to increase industry productivity,” Dr Vignier said. ![]() Study lead Dr Julien Vignier of Cawthron Institute said this study is very important for the domestic and international Pacific oyster industry. The quantity of stressed algae supplied to oyster larvae also influenced overall larval performance, with high feeding rations generally causing greater impairment than low rations. The bacteria-rich microalgae was fed to 11 day-old oyster larvae at two feeding rations for 96 h, followed by a recovery period.įeeding stressed algae to oyster larvae for 96 h increased the occurrence of deformities, reduced feeding and swimming ability, and slowed development. This new study, funded by Cawthron’s Shellfish Aquaculture Platform, aimed to assess the role of bacteria in oyster larvae health and development through exposure to poor quality microalgae feed and rearing seawater.ĭuring the study, researchers used a molecular technique called metabarcoding to identify the different types of bacteria in the samples of larvae tissue, seawater and microalgae feed. Outbreaks of bacterial infection via microalgal feed have long been linked to these mortalities. The Pacific oyster Crassostrea gigas is the world’s most cultivated oyster and seed supply is heavily reliant on hatchery production where recurring mass mortality events are a major constraint. The study, published in the journal Frontiers in Microbiology has revealed that bacteria present in microalgae-based feed significantly affects the health and mortality of developing oyster larvae in the hatchery environment. As such, Cawthron’s AAH research has broad implications for all of our shellfish research.īelow we’ll summarise some recent Cawthron studies focused on the health of shellfish in New Zealand.Ī recent study from Cawthron Institute has confirmed that bacteria in microalgae feed affects oyster larvae health and mortality ![]() There is a symbiotic relationship between the two research programmes as they share complementary objectives, interests and resources.Īs we explained in the Cawthron case study “ Climate change and shellfish aquaculture”, many AAH issues are also affected and or compounded by changing environmental conditions, and many of these issues have potential solutions through the development of new breeding, hatchery, husbandry and farm management practices and technologies. In addition to leading the national Shellfish Aquaculture Research Platform, Cawthron Institute also leads a Ministry of Business, Innovation and Employment-funded Aquatic Animal Health (AAH) Research Programme. We also lead a range of programmes of research and development that produce novel technology and solutions that protect and grow New Zealand’s aquaculture industry. We provide services to a range of aquaculture industry clients in New Zealand and the Pacific including aquatic disease diagnostic commercial services, pest and disease risk assessments and pharmaceutical trial services. Cawthron holds significant expertise in improving the health, welfare and biosecurity of our aquatic animals to the benefit of New Zealand’s economy and environment.
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