ROLE OF OPPORTUNISTIC Vibrio SPECIES IN LARVAL REARING OF THE MUSSEL Perna canaliculus  

Sarah Cumming*, Dan McCall, James Smith, Nicola Hawes, Rodney Roberts
Shellfish Production and Technology Ltd New Zealand (SPATNZ)  139 Glen Road, Glenduan, Nelson 7010, New Zealand  sarah.cumming@spatnz.co.nz

The New Zealand Greenshell™ mussel industry produces around 100,000 T/yr greenweight but still relies on wild-caught juveniles. Following many years of research by New Zealand mussel farming companies and the Cawthron Institute, a project is underway to commercialize hatchery spat production and selective breeding of Greenshell™ mussels. Shellfish Production and Technology New Zealand Ltd (SPATnz) recently built a pilot scale commercial hatchery in Nelson and is currently developing methods to consistently produce spat at the scale required. Spat have been successfully reared throughout the year and the facility has been designed assuming 8 successful batches per year. The main biological challenge at present is late stage larval rearing, with some batches succumbing to Vibrio species in the final week of larval rearing. Preliminary data indicate that Vibrio tubiashii is associated with loss of larval batches, and members of the Vibrio splendidus clade are associated with partial losses or reduced larval quality. These bacteria enter with gametes and remain in low numbers unless they spike during late larval rearing. We are interested in aspects of larval development or the rearing system that allow bacterial pathogens to dominate, and means of preventing this from happening.  Improving the consistency of larval rearing would help maximize the future output from the hatchery once commercialized.