Many people regard carp as the villain of our rivers, for these fish are believed to be expanding their distribution at an alarming rate, muddying the waters, and damaging the aquatic habitat for other species.
According to a new book from CSIRO, this picture has much to justify it: carp can adversely affect aquatic habitats, especially riverine billabongs, by increasing turbidity and uprooting certain species of water plants. These impacts are probably having a major impact on aquatic biodiversity.
"If carp comprise over 90% of the total fish biomass, as they do in some parts of the Murray-Darling Basin, then native fauna must be missing out badly," says Dr Jane Roberts, an ecologist with CSIRO Land and Water and one of the book's editors.
How and why carp have come to dominate our rivers are crucial questions. Has the regulation of our rivers provided ideal conditions for these fish? What this book does is to set the stage for controlling carp numbers.
Controlling Carp: Exploring the Options for Australia is an accessible summary of current scientific opinion on carp management. Bringing together ideas from a range of disciplines, with experts assembled for a technical workshop, it reviews options for controlling carp and identifies research and management directions.
The workshop was organised by CSIRO, the Murray-Darling Basin Commission (MDBC) and the Fisheries and Aquaculture Branch of the Department of Primary Industries and Energy.
"A national approach to the carp problem has so far been lacking," says Dr Roberts, "but an intergovernmental Carp Control Coordinating Committee is to be established to help formulate a unified approach.
"We need to develop strategies for controlling carp populations in entire river systems. It is clear that Australians value rivers and wetlands for their intrinsic ecological and multi-use values, not just for water. We want to shake the apparent indifference of governments to what inland communities now perceive as a major problem, one that has aroused much dissatisfaction, emotion, and debate."
Research on the impact of carp has been gaining momentum, and several research projects are now nearing completion. Some of these projects are supported by the Commonwealth and the States through the Natural Resources Management Strategy administered by the MDBC. A report on the cost of carp control has recently been prepared for the Commission by a small team led by Dr Roberts.
"After largely being ignored for two decades, carp are now firmly on the national agenda," she says.
Controlling Carp is available from Andrew Bell, CSIRO Land and Water,
Canberra, ACT. Phone (02) 6246 5717, fax 6246 5800.
For more information:
Richard Tilzey, Bureau of Resource Sciences, Canberra, Phone (02) 6272 4044.