New Zealand oyster farmers eye recovery

New Zealand’s Pacific oyster (Crassostrea gigas) industry has navigating rough seas for the last two years as a result of an outbreak of the ostreid herpes virus-1 (OsHV-1), but there are at last encouraging signs that the worst of the storm has passed. 

The virus, which is harmless to humans but deadly to juvenile Pacific oysters, first hit the Northland region’s oyster farms in April 2010 but wasn’t properly diagnosed until November of that year. Since then, production has plummeted and hundreds of farm workers have lost their jobs.

It’s estimated around 40 farms have been affected, comprising an area of 700 hectares. One major player, Sanford Ltd., was forced to close its processing plant indefinitely as a result of a shortage of product.

The same virus had previously devastated French oyster stocks, and the country — once Europe’s biggest producer — is still struggling to get its industry back on track, four years after the initial outbreak.

Callum McCallum, president of the New Zealand Oyster Industry Association (NZOIA), said following the emergence of the virus more than 80 percent of the young oysters died. Furthermore, the natural spat falls were wiped out in both 2010 and 2011.

McCallum explained that South Island oysters have shown no mortality, but that all northern harbors north of the Bay of Plenty on the east coast of North Island and north of the Kaipara Harbour on the west coast of North Island have shown OsHV-1 mortality.

“Pacific oysters are scarce in New Zealand,” said McCallum. “Production levels may be just 25 percent of pre-OsHV-1 levels.”

Both industry and authorities have been busy attempting to overcome the virus. So far, trials involving moving stocks 1 or 2 kilometers from infected farms hasn’t worked; similarly, deep water cultivation (15 meters deep) have suffered high mortality. However, the New Zealand government has invested to help the industry establish a hatchery-based breeding program to breed for virus resistance and McCallum remarked that the initial results look promising but that there’s “a long way to go.”

Meanwhile, this year’s natural spat in some of the challenged areas seem to be surviving, he said.

“We’re not out of the woods yet. Breeding a resistant oyster will take a number of years before there will be commercial volumes available.”

This year, the government has provided the oyster industry with NZD 407,000 (EUR 258,610, USD 321,580) from its Sustainable Farming Fund (SFF) for the Oyster Industry Modernization Project, developed in conjunction with Aquaculture New Zealand.

The funding will step up the work into selective breeding over the next three years and is being complemented by re-allocation of matching Ministry of Science and Innovation (MSI) funding over the same period, as well as similar investments from the industry itself.

The selective oyster breeding program has already benefited in the last year from NZD 150,000 (EUR 95,300, USD 118,515) in immediate support from the Ministry of Agriculture and Forestry (MAF) to enable virus resistance trials.

Most of the work will be carried out at the Cawthron Institute’s Nelson Shellfish Research Hatchery and on farms primarily in Auckland, Coromandel and Northland.

In the meantime, Pacific oyster prices are soaring in line with the curtailed supply. McCallum estimates they are currently around 50 percent higher than they were three years ago, when production was worth approximately NZD 30 million (EUR 19.1 million, USD 23.7 million) in annual sales, most of which was exported.

“We need these [price] levels to build in the risk associated with oyster farming,” he said.

The NZOIA believes that if all goes well, the industry’s goal of achieving annual sales of NZD 100 million (EUR 63.5 million, USD 79 million) within two decades is still attainable.


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