Legislative Council: Tuesday, May 02, 2023


Regional South Australia

246 The Hon. J.M.A. LENSINK ().23 March 2023). Can the minister advise:

1. What contingencies have the state government made with environmental flows to be released from Menindee Lakes into the Darling which will make its way into the South Australia via the Murray in the coming weeks?

2. Does the state government support the introduction of the carp herpesvirus to help manage increases of carp numbers?

3. How many of the six newly appointed Brand SA board members are from regional South Australia?

The Hon. C.M. SCRIVEN (Minister for Primary Industries and Regional Development, Minister for Forest Industries): I am advised:

1. On 16 and 17 March, mass fish deaths occurred in the Darling River between Lake Wetherell Main Weir and Menindee town, New South Wales. The dead fish were predominantly bony herring, with some Murray cod, golden perch, and carp also affected.

On 28 March additional fish deaths in the Darling River between Menindee town and Menindee Creek were reported, including hundreds of dead golden and silver perch.

Emergency releases of oxygenated water from the Menindee Lakes are occurring to reduce the risk of further fish deaths. This water is being debited from environmental water accounts.

Monitoring by New South Wales, including water quality testing for dissolved oxygen levels and pesticides, will identify if the operations have been successful and will inform future decision-making.

Environmental water will flow directly into South Australia and will not be diverted to Lake Victoria. This is due to inlet constraints caused by flood damage, as well as accounting arrangements made with environmental water holders.

Over 200 gigalitres of environmental water will flow out of the Lower Darling, diluting water containing low dissolved oxygen and improving water quality.

Once the Lower Darling water arrives at the junction of the Darling and Murray Rivers at Wentworth, the addition of the River Murray flows will further improve water quality.

Current estimates are that dissolved oxygen levels will be 4 to 5 mg/L once the waters are mixed. This is double what was observed during the flood peak late in 2022.

In South Australia, higher flow volumes will be maintained throughout April, as environmental water releases continue to pass into the state.

Because of the additional environmental flows and mixing of water from the Darling River with water from the River Murray, it is not expected that fish kill events being experienced in New South Wales will directly impact on South Australia.

The risk of lower water quality and subsequent fish kills may increase slightly beyond April, when environmental flows are reduced, but lower temperatures typically experienced at this time of year will help mitigate these risks.

The Department of Primary Industries and Regions are continuing to monitor the event and are prepared to act in accordance with the Operational Response Plan if fish kills do occur in South Australia.

The Murray Darling Basin Authority and SA Water are assisting with monitoring water quality in South Australia.

2. The National Carp Control Plan, released November 2022, was funded by the Australian government and led by the Fisheries Research and Development Corporation, to assess the use of the carp virus as a biological control agent for reducing the impacts of carp.

Technical papers accompanying the control plan cover a range of topics, including understanding whether the carp virus could impact on other species, its effectiveness, and the social implications and views on releasing the virus.

The control plan gathered significant information and provided insights into the feasibility of the carp virus as a biocontrol agent. However, it also highlighted that uncertainties remain regarding the efficiency and effectiveness of the virus in safely removing carp from Australian waterways. All governments need to formally consider this information before deciding to proceed with this program.

As the agency responsible for managing risks and policies related to invasive species, the Department of Primary Industries and Regions, on behalf of the government of South Australia, represents the state on the Environment and Invasives Committee, National Carp Task Group.

The Carp Task Group met on 15 December 2022 and 13 February 2023 to discuss whether to further examine the potential release of the carp virus as a biocontrol agent to control carp, including the outcomes of the control plan.

The Department of Primary Industries and Regions has considered other control methods for carp. The alternatives have typically had limited effectiveness, highlighting the importance of a national approach.

3. The six members of the newly appointed Brand SA board are high calibre, passionate advocates for South Australia and its diverse regions. They reflect the make-up of our state and its regions in a far greater way than Brand SA could have ever done following its disbandment under the Marshall Liberal government in June 2019.