Removal of St Georges Basin Caulerpa taxifolia ‘booms’

The booms and silt nets placed across the entrance of Smiths Lagoon in St Georges Basin are to be removed after Christmas. The booms and nets were installed three years ago in an attempt to prevent the spread of the invasive seaweed Caulerpa taxifolia (Caulerpa).

Aquatic Biosecurity Officer, Ms Brigid Krug, said a recent survey conducted by the Department of Primary Industries (DPI) had noted the deterioration of the nets and booms.  Installed initially as an interim measure to reduce the spread of Caulerpa, NSW DPI research has now concluded that the nets are no longer effective, and that they will be removed.  

NSW DPI Aquatic Biosecurity staff are working closely with Shoalhaven City Council and the contractor undertaking the removal to ensure minimal risk of spread of Caulerpa during the removal of the nets, and to ensure the best method of disposal.  

“Once the nets are removed, NSW DPI staff advise that the fishing (netting) closure will remain in place in Smiths Lagoon, and that where possible, boaters should avoid entering the shallow areas that Caulerpa occurs,” Ms Krug said.  

“During a recent visit to St Georges Basin, DPI research staff found a reduction in the density of Caulerpa in Smiths Lagoon. Surveys are planned within the coming 18 months to further determine abundance of the pest,” she said.  

“Although Caulerpa appears to have decreased in this area, we still urge the local community to be on the look out for new growths of Caulerpa because it is very dynamic – and can spread very quickly.”  

“Caulerpa is an invasive marine alga that is known to occur in 13 estuaries and coastal lakes in NSW. Caulerpa was first identified in St Georges Basin in April 2004.”  

“Fragmentation of Caulerpa is one of the methods that the weed can spread, and also the hardest to control. It is important that the community is aware that boating gear can easily cause fragments to break away from existing Caulerpa beds, and it only takes a 1cm fragment to regenerate a new Caulerpa bed elsewhere,” Ms Krug said.  

To report a suspected sighting of Caulerpa or any other aquatic pests in your waterway, call the 24-hr hotline 02 4916 3877 or email aquatic.pests@dpi.nsw.gov.au.