Optimised wetland carp separation cages

Project Leader: Dr Ben Smith, SA Research and Development Institute

Aim: To identify ways of exploiting carp spawning aggregations at wetland inlets.

Projects:  4.f.12

Project summary

In temperate lowland rivers, carp are allied with two important habitats: a shallow well vegetated spawning habitat, preferably in off steam wetlands, and a deep over wintering habitat in the main river channel. The shallow wetland habitat enables spawning and the replenishment of populations via recruitment. The deep habitat is thought to provide refuge from flow and maintain stable temperatures in comparison with shallow surface waters.

Movement between these two habitats is annually predictable, and results in localised accumulations of carp (spawning and over wintering aggregations). Carp aggregations are vulnerable to targeted removal programs and allow focussed, effective carp management efforts.

This project focussed on identifying ways of exploiting carp spawning aggregations at wetland inlets. Investigations evaluated the migratory (and jumping) ecology of carp through wetland inlets, including the application of existing Carp Separation Cage (CSC) technology for trapping and removing carp at wetland inlets. Required modifications to the existing Carp Separation Cage design were investigated, and a carp ‘pushing’ trap component was subsequently developed and incorporated into the cages and field trialled.

Key achievements

  • As part of this project, a literature review of carp movement and migration and possible sensory attractants for laboratory and field testing was completed, with four promising carp attractants identified: current flow, amino acids, water temperature and sound.
  • Experiments conducted by this project found carp were able to push as much as twice their body weight. The results of these measurements were used for the development and manufacture of a pushing trap element for incorporation into a wetland Carp Separation Cage.
  • An evaluation of wetland carp separation cages incorporating ‘pushing’ and ‘jumping’ trap elements was made at the inlet and outlet to South Australia’s Banrock Station wetland during 2nd June to 19th December 2008. Weekly sampling occurred to evaluate the performance of the traps and the lateral migrations of native and alien fishes. Carp were absent from June through until early August and this may offer some support for filling wetlands during the colder winter months to prevent their rapid colonisation and recruitment by carp.
  • Both the jumping and pushing traps proved a great success in removing large numbers of carp (around 8 tonne in 4 months) and both show great promise for wider application wherever carp migration pathways become spatially constrained ie wetlands, fishways, irrigation channels.
  • A draft decision support package to inform the selection and implementation of carp management options at wetland inlets has been prepared by this project and will be a valuable ‘path to adoption’ document.

Key deliverables

  • The final report for this project is due for delivery by the end of 2009.

Project team

Matt Pellizari, Anthony Conallin, Leigh Thwaites, Michael Decelis, Karl Hillyard.

Project partners

IA CRC, Murray-Darling Basin Authority, SA Research and Development Institute, University of Adelaide.

Further information

Conallin A, Hillyard KA, Gillanders BM and Smith BB (2009 submitted). Spatial patterns in the lateral migration of wetland fishes and other fauna. Regulated Rivers Research and Management.

Conallin A, Smith BB, Thwaites L and Gillanders BM (2009 in prep for submission by end July) Offstream movements of common carp (Cyprinus carpio L.) during wetland filling in the Lower Murray River, Australia. Marine and Freshwater Research.

Smith BB, Thwaites LA, Conallin A, and Fleer D (2009 in prep for submission by mid August) A combination jump and push trap to exclude and harvest mature common carp (Cyprinus carpio) at wetland inlets. North American Journal of Fisheries Management.

Smith BB, Thwaites LA and Conallin A (2009 in prep for submission by end August) Research Note: Carp prefer to jump migration barriers, rather than push underneath them. Fisheries Management.

Smith BB, Thwaites LA, Conallin A and Hillyard D (2009 in prep) Decision support package to inform the selection and implementation of carp management options at wetland inlets: a test case for South Australia.

Smith B and Thwaites L (2007) Carp spawning migrations and identification of sensory attractants – a scoping report for the Invasive Animals CRC. SARDI Aquatic Sciences Publication Number F2007/000712-1. SARDI Research Report Series Number 226.

Thwaites L, Fleer D and Smith B (2007) Conceptual development of a ‘finger’ style pushing trap for common carp, Cyprinus carpio. SARDI Aquatic Sciences Publication Number F2007/000790-1. SARDI Research Report Series Number 238.

Thwaites LA, Smith BB, Decelis M, Fleer D and Conallin A. (2009 in press) A novel push trap element to manage carp (Cyrinus carpio L.): a laboratory trial. Marine and Freshwater Research.

Final report of IA CRC project 4.F.12 Spawning migrations and attractant flows: Achilles’ heel exploitation of innate carp behaviours (unpublished).

For further information, contact us.

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