Carp Sterilisation Investigation Begins

With the support of the Department of Primary Industries, Parks, Water and Environment (DPIPWE), the Inland Fisheries Service recently began investigating a method for sterilising male carp. The aim is to develop an effective method for sterilisation that will prevent the risk of radio-tagged male carp inadvertently contributing to a spawning event. If the trials are successful, the Service will continue to use radio-tracking to locate carp spawning aggregations in Lake Sorell using sterilised male carp as radio-tagged fish during the 2011-12 carp spawning period.

Radio-tracking is an important tool for locating carp aggregations in the large expanse of Lake Sorell but it is also useful for understanding the behaviour of carp. By targeting its fishing effort in this way, the Service can capture and remove carp more efficiently. Successful sterilisation, therefore, is an important step towards the ultimate goal of eradicating carp from Tasmania.

Two methods are being trialled under the hands-on direction of DPIPWE’s Senior Veterinary Officer (Aquatic Health), Kevin Ellard. The first is chemical sterilisation by injection of Superlorin implant. This is less invasive; decreasing the threat to fish recovery, but it is a short term fix to reduce sperm count and is likely to wear off after a few months. The second and preferred method is surgical sterilisation, a vasectomy. This has increased likelihood of long term success and the radio-transmitter can be implanted at the same time.

To date, the vasectomy has been trialled on ten and the chemical implant has been trialled on four adult male carp. Six of the surgically sterilised carp were also implanted with transmitters. All of the fish have made 100% recovery with the use of antibiotics – an excellent result given warmer water temperatures and increased likelihood of infection. They will be held for observations over the coming months to determine the success of the strerilisation methods. If successful, it is planned to deploy those implanted with radio-transmitters into Lake Sorell during winter 2011, prior to the start of the spawning period in spring.