A line of dead Akoya pearl oysters (top) is shown next to a line of live, healthy ones. | EHIME PREFECTURE / VIA KYODO
The mysterious death of over 20 million Akoya pearl oysters in Ehime, Mie and other prefectures this summer is expected to hobble pearl production next year and beyond.
While the cause of the die-off is unclear, oyster producers have started taking steps to minimize the damage.
It takes three to four years to produce a cultured pearl, which the oysters make by depositing layers of nacre around a tiny bead inserted into their shells.
Ehime, the largest producer of Akoya pearl oysters in Japan, noticed the die-off in late July. At the end of September, the young shellfish cultured there stood at about 11 million, nearly 70 percent below average.
The die-off was the first in Japan since 1996, according to Takeshi Miura, a professor at Ehime University’s Faculty of Agriculture.
Courtesy of japantimes.co.jp
MARINE scientists are working overtime to identify a mystery illness that has decimated Port Stephens Pacific oyster crops.
Millions of Pacific oysters have died suddenly over the past two months. Almost all of a batch of a million juvenile Pacific oysters imported from Tasmania by fourth generation grower Geoff Diemar died recently.
“It doesn’t seem to matter if they are imported from interstate, produced at a local hatchery or are wild catch,” he said. “The ones that seem to be surviving best are the wild catch but it depends on where they are in the port.”
Pacific oysters are not sold from the port during summer. The disease does not appear to have affected other marine species, including the native Sydney rock oyster.
A NSW Food Authority spokeswoman said testing had shown there were no human health implications regarding water quality or the consumption of seafood from the area.
“Oysters, fish and other seafood remain safe to eat,” she said.
“The authority recommends people to always thoroughly cook any recreationally caught seafood.”
The Department of Primary Industries is also working with the Environment Protection Authority on the investigation.
Pacific oysters first appeared in Port Stephens in 1985 and have been grown legally in the port since 1989. The Pacific oyster industry employs dozens of growers and is worth about $5 million per annum.
A meeting between government agencies and growers is expected to be held when analytical test results come back in the next fortnight.
BIOSECURITY experts are scrambling to identify a mystery disease that has decimated Port Stephens’ multimillion-dollar Pacific oyster crops and sent several growers to the wall.
There are fears the port may have to be quarantined to prevent the disease spreading.
Hundreds of thousands of Pacific oysters have died since late last year.
‘‘We lost 600,000 oysters over a couple of weeks. We were struggling to find any live ones to be honest,’’ veteran Salamander Bay oyster grower Robert Diemar said.
‘‘We haven’t seen anything like it before.’’
Pacific oysters, which are worth about $3million to the Port Stephens oyster industry, had been recovering from a disease that swept through the region last year.
To date, it appears the latest disease has affected only hatchery-sourced Pacific oysters.
However, it is feared it may also attack prime Sydney rock oyster crops in the port.
‘‘It’s very frightening not only for the guys who are growing Pacific oysters, but also for the rest of us,’’ Port Stephens shellfish program chairman Don Burgoyne said.
‘‘If it was Pacific Oyster Mortality Syndrome we would have been quarantined by now.’’
Several farmers who had invested heavily in Pacific Oysters have been ruined by the disease. ‘‘It’s literally taken my business away; I don’t know what I’m going to do,’’ Andrew Richardson said.
‘‘There’s not much we can do but to diversify.
‘‘It’s going to take three years for Sydney rock oysters to grow.’’
A Department of Primary Industries spokeswoman said biosecurity and fisheries experts were working with growers to identify the cause of the mortalities.
Twenty batches of affected oysters had been tested at the Elizabeth Macarthur Agricultural Institute at Menangle since early last November, with all testing negative for the virus that causes Pacific Oyster Mortality Syndrome.
‘‘It is not clear yet what is causing the mortality event, it could be an environmental factor. In all submissions tested to date, there is no evidence of a disease consistent with a known infectious agent,’’ the spokeswoman said.
‘‘Therefore, without any evidence of an infectious disease, the department’s biosecurity and fisheries experts are unable to put in place quarantine measures.’’
The NSW Environment Protection Authority and the NSW Farmers Association have also been consulted.