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Keywords:

  • alien species;
  • conservation;
  • freshwater fish;
  • habitat modification;
  • introduced species;
  • invasive species;
  • risk assessment

Summary

1. The invasion of carp (Cyprinus carpio L.) in Australia illustrates how quickly an introduced fish species can spread and dominate fish communities. This species has become the most abundant large freshwater fish in south-east Australia, now distributed over more than 1 million km2.

2. Carp exhibit most of the traits predicted for a successful invasive fish species. In addition, degradation of aquatic environments in south-east Australia has given them a relative advantage over native species.

3. Derivation of relative measures of 13 species-specific attributes allowed a quantitative comparison between carp and abundant native fish species across five major Australian drainage divisions. In four of six geographical regions analysed, carp differed clearly from native species in their behaviour, resource use and population dynamics.

4. Climate matching was used to predict future range expansion of carp in Australia. All Australian surface waters appear to be climatically suitable for carp.

5. This assessment strongly reinforces the need for immediate management of carp in Australia to include targeted control of human-assisted dispersal, such as use of carp as bait by anglers, distribution to new locations by anglers and the use of the ‘Koi’ strain in the aquarium industry.

6. Given their historical spread, dispersal mechanisms and ecological requirements, the expansion of carp across most of the remainder of Australia is to be expected.