Sarah Herrmann, Yorke Peninsula Country Times

Oyster farms in Stansbury have been forced to close while authorities investigate whether food safety is at risk from brevetoxins produced by the microalgae Karenia.

At least six farms were closed from Monday, May 5, as a precaution under the Primary Produce (Food Safety Schemes) (Seafood) Regulations 2017.

The Department of Primary Industries and Regions told the YP Country Times on Friday, May 9, that further testing was underway to identify the specific species of Karenia.

“The detection was made during routine testing by the South Australian Shellfish Quality Assurance Program,” a PIRSA spokesperson said.

“SA Health advises that, while brevetoxin can cause illness if people consume contaminated shellfish, the concentrations are currently below the levels of concern.

“This means there is no public health concern.”

Previously, on May 5, PIRSA advised YPCT that water samples collected at Stansbury on April 23 had detected Karenia mikimotoi.

Pacific Estate Oysters owner Steve Bowley said he had sent multiple water and meat samples to PIRSA after observing the water turn “really, really dirty”.

“We’ve been growing oysters here for 20 years and, speaking to other growers that have been here longer than me, no one had ever seen anything like that,” he said.

“Our waters around here are (normally) pristine.”

Mr Bowley said he and fellow farmers were playing a “waiting game” until the Karenia species could be identified and its possible toxicity determined.

“These closures typically last a week so, if they last a week, well and good, no big deal,” he said.

“We would’ve lost a few grand in sales but we’ve still got the oysters so we’ll sell them next week.

“But if it turns out to be something more sinister, that could have widespread repercussions — not only for the oyster industry but the tourism industry.

“And the rec fish sector is enormous, so if people are unable to catch whiting then no one’s going to come to Yorkes.”

The SA Oyster Growers Association declined to comment.

Since early April, southern YP has continued to experience discoloured water, deceased marine life and reported human health symptoms linked to the Karenia mikimotoi algal bloom. 

This article appeared in Yorke Peninsula Country Times, 13 May 2025.
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