The eradication and management of European carp from two large freshwater lakes in Tasmania
Chris Boon1
Previously deemed absent from Tasmania, European carp (Cyprinus carpio) were first discovered in Lakes Crescent and Sorell in January 1995. As a result, the Carp Management Program was established to contain, control, and ultimately eradicate carp from the lakes. Through the development of various techniques over 12 years (1995-2007), a complete eradication of carp from Lake Crescent was achieved using an integrated approach. By using these strategies in Lake Sorell, the carp population was estimated to have been reduced to less than 50 fish by 2009. However, a spawning event which occurred in spring that year resulted in the introduction of approximately 50 000 carp. The techniques used to target these fish varied with life stage. Juvenile carp were initially targeted using rotenone poison, as they were concentrated in marsh environments. As they developed further, intensive netting, electro-fishing, barriers, and traps were used to target these fish as they became more mobile. Biotelemetry techniques were also used to gather knowledge of seasonable habitat preference.
A significant increase in netting effort has been implemented in response to declining catch rates as the carp population is continually depleted. Alongside intensive netting, radio transmitter implanted carp will be utilised in order to prevent spawning and to remove the remaining individuals from the lake. The most current population estimate calculated in March 2016 suggests that there are now less than 1200 fish remaining, with over 95% of the original population removed.