Investigating New Ways to Control Carp

Professor Peter Sorensen from the University of Minnesota, USA has been working with the Inland Fisheries Service carp management program over recent weeks at Lake Sorell on an important study in the use of fish pheromones as an attractant to assist in the eradication of carp. Pheromones are a chemical produced naturally by carp to trigger a social response such as a spawning aggregation in other carp. 

Professor Sorensen is a world leader in the study of fish pheromones for the control of invasive species. He has been contracted by the Federal Government through the Invasive Animal Cooperative Research Centre (CRC) to identify carp pheromones and develop freshwater products containing them. The products can then be used to manipulate the behaviour of target fish and assist in controlling carp populations in Australia and elsewhere in the world.

Tasmania was selected to conduct the trials of these freshwater products because of the intense effort, expertise and infrastructure already invested in carp management here. For instance, the State Government has invested significant resources in the control of carp in Tasmania since the species was first discovered in lakes Sorell and Crescent in 1995 and the carp management program continues to be a high priority for the Service.

As a result, the Service has collected valuable data on carp management over the years, conducted investigations and trials, and pioneered the implementation of a range of innovative techniques and strategies to successfully contain, control and eradicate carp (in the case of Lake Crescent). Hence, Tasmania has the infrastructure, knowledge, experience and commitment to carp management to ensure that the trials run smoothly and to greatly assist the international investigation.

In fact, the Service began trialling the use of pheromones as an attractant to catch carp five years ago. Large female carp were used a source of pheromones by injecting them with a hormone to induce ovulation and placing them in secure bags behind carp fish traps at certain locations in the lakes. The current investigation will empower the Service to use the latest techniques to achieve control of the remaining carp in Lake Sorell.

Professor Sorensen’s work to date indicates that there are several factors – both environmental and biological – that impact on the effectiveness of the hormone generator fish in attracting others. The current trials consist of a number of fish that have either been injected (males) or implanted (females) and then placed at hotspots in the lake to attract others into traps. The trials will continue over the next month while the environmental stimulation remains for the carp and this should improve as the weather warms.

Professor Sorensen has now returned to the United States but will revisit Tasmania next year to follow up on this work. Meanwhile, the Service will continue to collect data on water temperature and flow rates, as well as recording capture rates and reproductive states of trapped fish, and the location and movement of carp. All this information will be analysed to determine the success of the pheromone generators to attract fish and to assess the correlations between the biological and environmental parameters that impact on the effectiveness of the trapping methodology.