Ohiwa oyster farm decimated by virus

Ohiwa Oyster farm owner Rick Yorke says it took only five days for a virus to almost wipe out his six-hectare aquaculture farm.
Mr Yorke's oyster farm is one of a growing number of North Island marine farms suffering a jump in the mortality rate of juvenile oysters (known as spat) - an increase that has the potential to cause a severe shortage in oyster numbers for the next season.
And while national reports suggest only the spat are dying, a trip out to Mr Yorke's farm makes it obvious the adult oysters have been just as severely affected.
As he pulls up clump after clump of 2-year-old oysters from their beds, his heart sinks further as, on average, only one of five or six oysters is still alive.
Row after row of empty oyster shells paints a bad picture although Mr Yorke jokes the crabs and flounder will be nice and fat after eating the decaying shellfish.
"I went out on November 22, and instantly realised things weren't looking good," Mr Yorke said.
He called Ministry of Agriculture and Forestry (MAF) Biosecurity New Zealand.
"I phoned the powers that be on the 22nd and they said 'oh no - not you too '."
Mr Yorke is not sure whether he is the only oyster farmer in the country whose adult oysters have been hit or other farmers are wanting to protect the industry.
"With what I've seen I would say this virus has wiped out oysters for the next two seasons," Mr Yorke said.
"Prior to it ripping through my farm I had been looking at two potentially great harvests."
He says the most heartbreaking thing he has had to do since discovering the carnage was laying off one of his permanent staff, further job losses are also on the cards.
Mr Yorke has owned the oyster farm for close to 14 years and is unsure of the future of his business for the next couple of years.
"The government have stepped up for the kiwifruit growers - maybe they will for us too."
Meanwhile MAF and the New Zealand Oyster Industry Association for Aquaculture New Zealand are investigating the virus.
Aquaculture New Zealand CEO Mike Burrell says since mid-November farmers have seen an increase in the mortality rate of young oysters on farms from the Bay of Plenty in the east and from north of Kawhia in the west.
"Typically, mortality rates for cultivated Pacific Oysters are between five and 10 per cent.
"This year, however, the rates on some farms have varied between 30 to 80 per cent which is very concerning for the industry," Mr Burrell says.
MAF has its aquatic disease specialists on the case and has taken approximately 250 samples for analysis to try and determine what is causing the die-back.
MAF response manager Richard Norman says the investigation is still in its early days and to speculate on the cause of the deaths and any likely impacts would be premature.
"What is clear is that both MAF and the industry understand the urgency around the issue and the need to identify the problem and find ways to address it," Dr Norman says.
The New Zealand Food Safety Authority says there is nothing to suggest any food safety concern with oysters, whether distributed for local consumption, or exported.