Demonstration site: Lachlan, NSW

Project Leader: Dean Gilligan, Industry and Investment NSW

Aim: To identify and implement targeted carp control options for the Lower Lachlan Catchment.

Project: 10.f.9

Project summary

The lower Lachlan River, including its tributaries and floodplain wetlands is recognised as a Priority High Conservation Value Aquatic Ecosystem in New South Wales.

Key threats to this vulnerable area include invasive species such as carp and the impact of river regulation on fish passage and the habitat of vulnerable species. The density of carp in the Lachlan catchment is the highest of any catchment in New South Wales, and is probably the most abundant carp population in Australia. The carp population in the lower Lachlan is supported by several carp recruitment ‘hotspots’: the Great Cumbung Swamp, Lake Brewster, Lake Cargelligo and Lake Cowal, each having features amenable to trialling of control options. The Lachlan River is also largely isolated from the remainder of the Murray-Darling Basin.

In the initial two years (the benchmarking phase), the focus of the project was on benchmarking the status of the carp population and the aquatic ecosystem in the lower catchment (and control sites established in the Macquarie-Bogan catchment to the north and the lower Murrumbidgee catchment to the south).

A second component of the project in the initial two years was the establishment and assessment of a number of replicate ~50 m2 carp exclosures (these quantify the impact of carp on aquatic vegetation, macroinvertebrates and native fishes, quantify the expected rate and potential for ecosystem recovery within the broader catchment, and provide a visible focal point for demonstration of the benefits of carp control to the community).

Key achievements

  • Benchmarks have been established for the size of the carp population, relative level of carp recruitment from each hotspot, and the status of water quality parameters, riverbank stability, aquatic vegetation cover, native fish community composition throughout the lower catchment and social attitudes towards carp, their impacts and the activities of the project.
  • 3085 carp were tagged (to June 09) and released so that mark-recapture estimates of population size can be obtained, and so that the effectiveness of carp removal activities (planned for the phase 2 project) can be gauged on the proportion of the population removed. 63 have been recaptured.
  • 50 carp were collected from five locations. Otolith micro-chemistry is being analysed to determine if their spawning location can be identified by intrinsic otolith micro-chemical signatures.
  • Fish surveys were completed in the lower Lachlan River, in mid-Autumn in 2007, 2008 and 2009. Carp made up 84.5 per cent of the total biomass within the Lachlan River and were present at every site that was sampled.
  • The Lachlan River Carp Cleanup held the official launch of the River Revival in Forbes on the 16th Sept 2009. The launch introduced the next stage of the Lachlan River Carp Cleanup.

Key deliverables

  • A report detailing the results of benchmark sampling and progress towards preparations for implementation phase.

Project team

Bob Creese, Simon Hartley, Dean Hartwell, Cameron McGregor, Adam Vey, Sam Davis, Bill Bardsley, Ben Smith, Dale McNeil, Anthony Conallin, Karl Hillyard, David Crook, Ivor Stuart, Keith Bell, Allan McGufficke, Michelle Jefferies.

Project partners

IA CRC, Murray-Darling Basin Authority, Industry and Investment NSW, SA Research and Development Institute, Lachlan CMA, Vic DSE, Kingfisher Research Pty Ltd, K&C Fisheries Global Pty Ltd, NSW State Water, Local community representatives as coordinated by the LCMA.

Further information

Penfold K (2009) Lachlan trial for carp removal in Fish Fisheries Research and Development Corporation, June 2009 pp24-27

For further information, contact us.