Estimates by fish experts indicate that the numbers of Carp have increased by over 40 times in parts of the Murray Catchment and there are reliable reports of large numbers of carp, (1600 per day), passing through fishways at Torrumbarry Weir on the Murray, or accumulating at weirs such as Stevens Weir on the Edward River.

Efforts to trap carp have rarely been successful because of a lack of effective control techniques, but a new “carp cage” has been trialed successfully at Blanchetown in South Australia, where it has removed 200 tonnes or 80,000 carp since 2008.

The Williams cage, designed by Alan Williams, weir-keeper at Torrumbarry, uses an innovative design to allow native fish to pass through, while using the jumping behaviour of carp to trap them.

Willams carp cages can be easily installed at fishways, but they need detailed planning and on-going management to be successful.

Carp degrade aquatic ecosystems, causing a decline in the numbers and diversity of native fish. Their detrimental impact comes from their constant drive to spread as far and as fast as they can into creeks, billabongs and channels.

The Murray Catchment Management Authority has engaged a leading carp scientist, Dr Ivor Stuart, to work with its own carp specialist, Anthony Conallin, to investigate the feasibility of installing carp cages on a number of fishways within the NSW Murray Catchment.

Dr Stuart advised that each fishway will be evaluated against environmental, social and economic criteria to ensure that the design, construction, operation, and cost-effectiveness are addressed.

“Carp harvesting will have obvious benefits to the environment” Dr Stuart said.

The Murray CMA is working in close partnership with the Office of Water, State Water, Department of Primary Industries - Fisheries and Murray Goulburn Water on this project, and will be involving fishing clubs, interest groups, and the wider community in the feasibility study for the carp cages.