Bacterial pathogens of oyster larvae (Crassostrea gigas) in a Tasmanian Hatchery

Abstract

Diseases causing high mortality occurred in a hatchery for rearing juvenile oysters, C. gigas, at Bicheno, Tasmania, during 1980. Outbreaks of the disease characteristically showed three peaks: in 7-10-day- old larvae, in older larvae several days before setting, and in spat 1-2 weeks after setting. Various marine bacteria were cultivated from inactive larvae and other hatchery specimens, and the predominant strains were identified. When given to normal young larvae at doses of 1 × 10⁵-5 × 10⁵ or 1 × 10^-5-5 × 10⁷ bacteria (total dose), seven strains (five strains of Vibrio, two strains of Alteromonas) caused fatal infections in most animals. This is the first report of pathogenic marine bacteria in an Australian shellfish hatchery.