The project, ‘Supporting Increased Aquaculture Production Through Reduced Harvest Closures’, will receive over AU$1.5M to support evidence-based decision making on the closure of productive oyster harvest areas following sewage overflow events.
As ‘filter feeders’, shellfish can accumulate pollution from catchment runoff and overflows from the sewage network can pollute estuaries. Currently, limited quantitative is data available to support decision makers on harvest closures, thus, a precautionary approach to harvest closures is taken—being a minimum of 21 days following a sewage overflows.
Led by WRL's Director of Industry Research and Principal Environmental Engineer Duncan Rayner, the project is designed to minimise disruption to the aquaculture sector by ensuring that oyster harvest closures occur only when there is a health danger posed to consumers.
Rayner says that frequent closures significantly impact oyster production and harvest in NSW estuaries.
“During wet years, repeat closures can result in a significantly reduced, and sometimes non-existent, harvest—and ongoing closures heavily impact shellfish producers through lost sales, reduced yield, and multiyear economic impacts,” says Rayner.
“Reducing the instances of harvest area closures would have major benefit to individual growers, the wider industry, and the regional communities where shellfish production occurs.”
In conjunction with the NSW Shellfish Program (DPI Biosecurity and Food Safety), WRL will develop predictive computer models for ten shellfish growing areas that have been severely impacted by sewage spills in recent years. With these models, the NSW Food Authority will be able to assess overflow events on an individual basis when sewage spills occurs, reducing the number of days closed to harvest.
Ten highly-impacted estuaries were chosen to be studied: Tweed River, Nambucca River, Merimbula Lake, Wallis Lake, Camden Haven, Shoalhaven/Crookhaven Rivers, Pambula Lake, Port Stephens, Wagonga Inlet, and Clyde River. The Hastings River estuary will also be assessed under a separate NSW Government Coasts and Estuaries Grant. Collectively, these estuaries represent over 81% of total NSW oyster production.