ASFB Home > 2003 > Biological Invasions: Consequences for Parasites, Pathogens, Emerging Diseases, and Fisheries in the Marine Environment.

Will Restoring Native Fish Habitat In The Murray-Darling Basin Simply Increase The Availability Of Habitat For European Carp?

Simon Nicol, Jarod Lyon and Jason Lieschke

Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Victoria, Australia, 3084.
Email: Simon.Nicol@nre.vic.gov.au

Populations of native fish in the Murray-Darling Basin are estimated to be as little as 10% of their pre-European settlement levels. As a consequence, a large program of investment has commenced to improve the ecological health of the Basin with clear goals to increase the viability of native fish populations. The restoration of physical habitat, through the reintroduction of large woody debris (LWD) into the Basin’s large lowland rivers, is a key component of this investment program. There is overlap in habitat use between native fish and European carp (Cyprinus carpio) and consequently there is an expectation that restoration of physical habitat would benefit both groups. Actions that actively promote carp habitat are not desirable since agencies are also managing for the control and eventual eradication of carp. To validate fish habitat relationships, a large-scale experiment was conducted on the Murray River between 1999 and 2002. The experiment tested the response of both the native and exotic fish fauna to the strategic placement of new LWD habitat, located at differing sites within the river channel. Native fish responded positively to the placement of LWD, whereas carp did not utilise the newly available habitat. This demonstrates that the strategic placement of LWD into lowland rivers can have positive benefits for native fish without increasing the availability of habitat for carp.

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