The oyster farming industry in the North Island is on the verge of collapse.
A herpes virus that has attacked young Pacific oysters over the past two summers is killing up to 95% of spat, leaving farmers with almost nothing to sell.
The industry is worth about $30 million a year, with more than two-thirds of the oysters exported.
Stock losses in the last season have been so great that Sanford on Monday announced the closure of its Kaeo processing plant in Northland.
Fifteen permanent jobs and about 50 seasonal jobs will be lost.
The Oyster Industry Association says the best hope is that resistant strains of Pacific oyster can be bred and farms re-stocked over several years.
Spokesperson Callum McCallum warns the industry is in big trouble. He says the Pacific oyster herpes virus has devastated marine farms from Parengarenga in the Far North to Whakatane and the Kaipara harbour.
Virus cause unknown
The Ministry of Agriculture and Forestry says it is not sure why the virus is occurring.
Deputy director-general Scott Gallacher says it could be to do with higher water temperatures causing stresses but this is not necessarily tied to global warming.
Mr Gallacher said an unusual number of juvenile oysters are dying and a selective breeding programme is being considered to combat the virus.