Use of ground saline water for intensive rearing of Ruditapes philippinarum juveniles in a nursery system. Aquaculture – The Farming and Husbandry of Freshwater and Marine Organisms. The effects of acidic seawater on three species of lamellibranch mollusc. Compensatory growth in the Bay Scallop Argopecten irradians. A generalized growth and mortality model for assessing the economics of bivalve culture. These results are discussed in the light of usual oyster farming practices and selective breeding.Īskew C.G. However, two groups can be distinguished among those which died during the experimental period, one which showed a decrease in weight and the other whose growth was similar to surviving oysters. Mortality mostly occurred between 3 and 5 months and appeared to affect the slow-growing animals more. A significant group effect was observed on survival and on growth rate. Early growth rate was a very good predictor of size later in life: 66% of variation in the live weight at 10 months could be explained by variation in the initial growth rate calculated between 3 and 4 months. The individual growth performances were relatively stable over time and no noticeable compensation for growth occurred. Oysters were individually monitored for growth and survival from 3 to 10 months after fertilization. Larvae were reared under conditions allowing the maintenance of a maximum variability of size and gave five experimental groups. Four groups of larvae were obtained by crossing five males and five females from each of the four sites, and a fifth group by crossing these 20 males and 20 females together in a pool. 'The only hope for the industry is a better understanding of the disease, better genetics and in the meantime, growing alternatives.In order to study individual growth variability and its relationship with survival in juvenile Crassostrea gigas, parental oysters were sampled at four sites located along the French Atlantic coast and bred under controlled hatchery conditions. 'This disease of Pacific Oysters is unlike any other animal disease in Australia, with such a high mortality rate and the inability to restock a farm as it returns,' Dr Whittington said. New Zealand has suffered substantial oyster losses from POMS and is trying to recover its industry.ĭr Whittington, veterinary lead at the Aquatic Animal Health team at Sydney University, said the disease could have arrived in Tasmanian waters from ocean currents, as ships' ballast or in recreational boats. POMS is present in Spain, the Netherlands and is now progressively spreading to Denmark. The disease outbreak in Pacific oyster farms along the Atlantic and Mediterranean coasts of France 'destroyed half the industry and it has never recovered', according to Australian expert Dr Richard Whittington. The first reported outbreak of POMS was in France in 2008. POMS research indicates that outbreaks are temperature dependent, with a higher water temperature increasing the risk. It kills up to 80 per cent of oysters between 12 months and two years old, and 50 per cent of adult oysters over four years old. POMS causes 100 per cent mortality in juvenile Pacific Oysters, or spats. The virus weakens the oyster, causing the valves to open, and they die within hours. Host-specific to the Pacific, or Crassostrea gigas, it does not affect Sydney Rock Oysters, mussels, scallops, pearl oysters or the native Angasi oyster. POMS is caused by the virus OsHV-1 micro variant. Within 36 hours they were all gone.' How does POMS affect Pacific oysters? 'Collectively as a group, we probably had about 10 million juveniles we had just put in the water,' he said. Then in January 2013, POMS struck oyster farms on the Hawkesbury River north of Sydney, destroying millions of dollars worth of livestock.įarmer Bruce Alford said the speed of the disease in the Hawkesbury River had taken oyster farmers completely by surprise. Subscribe for the national headlines of the day. Within three months it had spread to the Parramatta River in western Sydney. POMS was first discovered in the New South Wales Georges River south of Sydney in November 2010. The race is on to breed a resistant species, with researchers still two years off delivering that outcome. Three hatcheries in Tasmania normally supply 90 per cent of the Pacific oyster spat in Australia. Its discovery in Tasmania has brought the industry to a standstill, with no movement of oyster spats from hatcheries to New South Wales or South Australia. The disease was first discovered in Australia in 2010 after an outbreak in France in 2008. Pacific Oyster Mortality Syndrome (POMS) is lethal only to Pacific oysters and kills them within hours of detection.

Oyster spat mortality rate