Fish Facts

Fish Facts: Carp

Fishers in Australia generally detest European Carp (Cyprinus carpio) although they are important food and sportfish in their native Asia, and also in Europe, where they were introduced before the middle ages.

Carp are a highly invasive exotic species which, like their terrestrial equivalents the rabbit and cane toad, have caused significant ecological damage to our inland waters. Despite the best efforts of authorities and responsible fishers to stop them, Carp are continuing to spread within Australia. Some recent genetic sleuthing by scientists from the University of Sydney has uncovered some interesting information on where carp in Australia have come from, where they are moving to, and also hints as to who has been moving them around.

The genetic studies have confirmed that there are at least four genetic strains of carp in Australia, namely koi, Prospect, Boolara and Yanco strains. There have been at least four and possibly up to 16 or more separate attempts to introduce the species from other countries. The first attempt at introduction was into Hobart, Tasmania in 1856, but that was unsuccessful. The first successful introduction of the “Prospect strain” into Prospect Reservoir near Sydney is generally recorded as being achieved in 1872, but later introductions continued till at least 1908. Once established, fish from the reservoir were then used to seed other populations around the Sydney Basin, including the Hawkesbury-Nepean River system. Until recently it was thought that the Prospect strain was confined to the Sydney Basin, however the new genetic data has shown that it has also been translocated into the Hunter River and throughout much of the Murray Darling Basin, probably due to illegal translocation by coarse anglers or by anglers using them as bait. Genetic fingerprinting has shown that all carp from Prospect Reservoir and most from the Hawkesbury–Nepean and Hunter Rivers originated exclusively from ancestors in Europe.

In contrast, all of the Koi carp in Australia originate from ancestors in Japan. The genetic sleuthing has shown that Koi have been introduced into a large number of water bodies near virtually every major population centre in Australia, including Perth, Sydney, ACT, Melbourne, Tasmania and near Brisbane. Koi carp are the dominant strain in the Parramatta River, with all fish sampled from there showing at least some koi ancestry. Koi are also interbreeding with the Prospect strain in the Parramatta, as well as other places like Hawkesbury–Nepean and Hunter Rivers. Koi have also been reported in the Murray Darling Basin and also in the Richmond, Bellinger, Hastings, Karuah, Towamba and Macleay catchments in coastal NSW, suggesting a large number of irresponsible releases of koi carp have occurred in the past, and probably are still occurring today.

The Yanco strain was introduced into the Murray Darling Basin between 1910 and 1950. Due to its orange colour, it is was originally thought to be a feral strain of koi origin from Singapore, though new genetic data suggests it is a colourful variety of common carp. The Yanco strain was originally thought to be confined to the waters of the Murrumbidgee Irrigation Area, though genetic analysis has shown they have now been spread into other parts of the Murray Darling Basin and have interbred extensively with the Boolara strain. The Boolara strain was originally imported from Germany (probably illegally) by Boolara Fish farm in Victoria in 1960. This strain is now distributed throughout the Murray-Darling Basin, where it dominates catches and shows a variety of colours and forms, including mirror carp and hybridisation with koi. A separate introduction of a strain similar to the Boolara strain has occurred in the Hunter River as well as the Logan and Albert Rivers near Brisbane. A mixture of Prospect and Boolara strain carp have also been introduced into Tasmania several times since the 1960s, and were successfully eradicated from at least two areas, but in 1995 more carp were found in Lake Crescent and Lake Sorell in the central highlands, and attempts continue to eradicate them completely, continue.

Carp are very closely related to goldfish (Carassius auratus), which also originated from Asia and which feral populations have also established throughout most of Australia. Goldfish are generally easy to tell apart by their smaller size (generally no more than 20 cm) and the absence of barbels in each corner of the mouth. In contrast the carp grows to a maximum size over 120cm and can reach 60kg overseas, with fish in Australia regularly exceeding 85cm and 15kg. Hybrids between carp and goldfish have been reported in all locations where the two species occur in Australia. Overall, approximately 1.6 per cent of the genetic diversity of carp in the Murray Darling Basin was found to be sourced from goldfish, and approximately 1 per cent of feral goldfish genetic diversity is sourced from carp.

Readers are reminded that because carp are so invasive and damaging to the ecology of our inland waters, and because it appears some people think it is a good idea to spread them around, it is illegal to be in possession of live carp (or even dead carp in some juridsdictions). The fines for failing to comply with local regulations can be severe, so make sure you check your local fishing regulations before helping our environment by taking out some carp.

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