A slice of scientific ingenuity has overcome a problem facing the mussel industry.
The Cawthron Institute in Nelson has developed a way of cleansing mussel spat (juvenile mussels) of a toxin-producing alga that was found in New Zealand for the first time last year.
Aquaculture scientist Kevin Heasman said he had been
working on the project since the algal bloom affected much of the North Island's west coast late last year.
The alga, gymnodinium catenatum, produces toxins capable of causing potentially fatal paralytic shellfish poisoning. The bloom led to the mussel industry declaring its largest source of spat in Northland off-limits.
Without access to that source - which supplies about 80 per cent of the industry's spat - mussel farmers feared a big shortage of mussels in 12 to 18 months.
Mr Heasman said his research had focused on cysts produced during the alga's life cycle, which could lie dormant for some time.
The microscopic cysts washed up on the beach with the spat among seaweed, he said.
The cleaning process involved washing the spat out of the seaweed, then putting it through a machine to separate it from the cysts.
The machine, a type of foam fractionator, produces bubbles to which the cysts attach themselves. The bubbles rise and overflow into a container, the contents of which are heated to kill the cysts.
Mr Heasman said the process had been developed to the point where the spat left behind in the foam fractionator were completely free of cysts.
It was now being used as a model for spat-cleaning operations being developed by mussel farmers.
Mr Heasman said strict testing procedures were in place to ensure no cysts slipped through.
The $50,000 project was financed by the Mussel Industry Council and Technology New Zealand, an offshoot of the Foundation for Research, Science and Technology.
Mussel Industry Council chief executive Paul Lupi said it was a "real breakthrough" for the industry.
Though the algal bloom had largely disappeared, a lot of cysts were still around.
He said the transfer of spat from Northland was still banned, except to approved cleaning sites.
- NZPA
