Oyster farmers report stock losses worth over $4 million after mass mortality event

OYSTER farmers are reporting a mass mortality of oysters from leases in the Myall River, estimating stock losses worth over $4 million.

They believe run-off from acid sulfate soils entering the estuary to be the cause.

The leases in question are opposite the Winda Woppa reserve, downstream from the Singing Bridge that connects Tea Gardens and Hawks Nest.

Third generation oyster farmer Stuart Lyall of Lyall’s Oysters in Karuah told NOTA he has lost around 840,000 juvenile oysters from the Myall River leases.

“We have lost approximately 70,000 dozen at the moment, possibly more,” said Stuart, whose family has worked in oysters since the 1920s.

“We are not sure with the larger oysters whether they are going to survive or not.”

Across all the local growers, more than 270,000 dozen oysters have been impacted.

“This is equivalent to over $4 million at an average wholesale price for a medium sized oyster,” said Stuart.

A 45-year veteran of the industry, Stuart said all signs point to “acid sulfate run-off entering the river system”.

“It happens in every estuary, so we are well aware of how it affects the oysters and what signs to look for,” he said.

“There are holes in the backs in the oysters… the oyster shell is made out of calcium, and the acid will eat the calcium away.”

Having lost stock and potential income, Stuart said it will be “very hard” to maintain his customer base.

“It will be very difficult to maintain the business due to the loss of income we will have in twelve months’ time,” he said.

Karuah oyster farmer Kayleb Hawes, Manager of Nelson Bay Oysters, said the business had lost over 500,000 oysters (42,000 dozen) in the past few weeks “due to the acid”.

“That is about 65 percent of everything we have,” he said.

“When you are flipping stock and having a look you notice that there are holes burnt all through them and all the shell is white.

“You can’t really miss it.”

A 2011 study published by the CSIRO found that run-off from acid sulfate soils (ASS) has “severe environmental and economic impacts on estuarine ecosystems”.

“Oysters display reduced abundance, growth rate and shell thickness when exposed to ASS runoff,” the study stated.

Stuart said he has had “no response at all” from the government agencies involved in the management of oysters as to the cause of the mass mortality.

News Of The Area contacted MidCoast Council, the NSW Environment Protection Authority (EPA) and the Department of Primary Industries and Regional Development (DPIRD) with questions on the potential cause.

Both the EPA – the state’s environmental watchdog – and DPIRD – the agency responsible for the “sustainable management” of commercial oyster farming – said that MidCoast Council is the lead authority on the investigation.

Council told NOTA that it had investigated run-off concerns relating to a local development site.

“MidCoast Council’s Environmental Health and Compliance teams are responding to a complaint which alleges that there is a potential impact from acid sulfate soils on a local development site at Hawks Nest,” a spokesperson said.

“In response to receiving this complaint, a site inspection was conducted by Council officers and officers from the NSW Environment Protection Authority.

“As part of the site inspection soil and water tests were undertaken.

“Test results received this week indicate that there are no anomalies on the site and that the results are consistent with stormwater runoff from surrounding land.

“These test results have also been forwarded to the NSW Environment Protection Authority.”

Council says its officers undertake regular site inspections to ensure that all works are undertaken in accordance with the development approvals over the land.

“These approvals require detailed construction and acid sulfate soil management plans to be developed and implemented during construction.

“These plans have been prepared and are being implemented on the site.”

THE EPA noted that DPIRD has established a working group to support oyster growers, and address water quality issues and oyster mortality in the area.

A spokesperson for DPIRD told NOTA, “DPIRD has provided advice to aquaculture permit holders to report the alleged acid sulfate soil impacts to Council.

“DPIRD has hosted meetings and supported oyster growers to liaise with regulatory authorities.”

By Doug CONNOR