Eradicating the European Carp from Tasmania

Diggle, John¹, Tim Farrell¹, Paul Donkers¹, Rodney Walker¹, Jemery Day² and Nicholas Bax²

¹Inland Fisheries Service, PO Box 288, Derwent Park, TAS, 7009, Australia
²CSIRO Marine Research, GPO Box 1538, Hobart TAS 7001, Australia
Email: nic.bax@csiro.au

European carp (Cyprinus carpio) was discovered in 1995 in two Tasmanian lakes. The decision was made to eradicate the carp from these lakes before they could spread downstream and further degrade the environment and recreational fisheries. Draining or poisoning the lakes was not a preferred option because of engineering and environmental constraints. The carp would be eradicated from the lakes through fishing. Unlike many fisheries, our objective is total eradication of the population – this fishery has no catch restrictions and no direct commercial value. We describe the approaches used to maximise the effectiveness of our fishing effort – the many gear types used, recruitment reduction, radio-tagged Jonah fish, sex-ratio biasing, etc. We describe the difficulties that we are facing in removing the last few fish – gear avoidance, changes in behaviour, eagles stealing the tracker fish, etc. To support the eradication effort we developed a model, which uses daily catch and tag return data to find maximum likelihood estimates of population size, tag shedding rates and mortality rates. We present the results from this model. Lastly, we comment on the lessons learnt from this eradication and the implications for the eradication of other carp populations through fishing.

Room 1 Tuesday 9.50 am