Oyster farms on the NSW South Coast have suspended harvesting due to waterway pollution caused by bushfires.
"After the big fires last week, physical damage was minimal to most oyster sheds in the region, however we're now facing issues regarding water quality," said Mark Allsopp, chief executive of Australia's Oyster Coast (AOC).
"A lot of farmers have not been able to harvest or transport oysters, and therefore significantly down on income during what should be the busiest time of the year."
The AOC supplies oysters from the South Coast's eight estuaries to restaurants and fish shops around Australia. Four estuaries - Shoalhaven, Clyde River, Tuross Lake and Narooma - have been closed for harvest due to higher readings of algae and other contaminants.
"While ash debris is considerable around oyster leases in many South Coast estuaries, it is considered that runoff from fire grounds and mobilised sediments pose more of a risk for oyster health and quality," said a spokesperson for the Department of Primary Industries (DPI) which is working closely with NSW Food Authority, Crown Lands and NSW Farmers Association to immediately address the impacts of the bushfires on oyster producers.
"The oyster industry operates under a stringent food safety and quality program," the spokesperson said. "Consumers can be confident that oysters in the market are safe to eat."
Allsopp said it is "too early to say" when the closed estuaries will be open again for harvest.
"It could be a couple of weeks, it could be a month. It just depends on tides and mother nature, and when she wants to mop up all the organic matter creating a high bacteria count."
However, the threat of estuary pollution will be ongoing for oyster farmers, even after being given the all-clear to harvest again.
"With all the ash and silt pouring into estuaries, if we get rain there could be more algae because of excess nitrogen and organic matter in the waterways," said Allsopp.
"That algae can suck oxygen out of the water, so our oysters are potentially facing significant mortality due to suffocation. That could be anytime over the next 12 months. It just doesn't seem to end."
The DPI spokesperson said longer term concerns, including the potential decline of water quality following rainfall, are currently being addressed.
There are more than 80 oyster farms operating in South Coast estuaries between the Shoalhaven River and Victorian border. Select farms in Wonboyn and Merimbula estuaries are still harvesting oysters 500km south of Sydney, however local farmer Hugh Wheeler said the lack of tourism in the area is also having a significant impact on business.
"We're feeling a little bit blessed that we're oyster farmers and not livestock or crop farmers, but at the same time we're heavily reliant on the success of our South Coast tourism industry.
"We sell a lot of oysters to Victorian tourists, in particular, and at the moment there's none of them here. I live looking over the local [Merimbula] caravan park which usually houses up to 6000 people at this time of year. Right now, you would be lucky to count two families down there."