Under-ice aggregations might teach us about carp behaviour
Ten days ago I was in Minneapolis, Minnesota looking at a range of carp behaviours that we will never see in Australia. The Common Carp that is the number one pest fish in Australia is also a major pest in the United States, and our Cooperative Research Centre has worked with the University of Minnesota for a few years on carp behaviour. Specifically, we are interested in how carp communicate via chemicals that initiate certain behaviours. In Minnesota's iced-over lakes, the carp group together, most likely in the warmest parts of the lake or where oxygen content is highest.
Commercial fishermen exploit this behaviour to catch the carp, usually sonar to locate the fish. They surround the fish with seine nets, sending them under the ice with submersibles. In the picture, a commercial fisherman is drilling a hole through a metre of ice to then use a sonar to find the fish.
Obviously in Australia we don't have lakes that ice over like those in Minnesota. But we are interested in how the fish are communicating and whether we can use this information to target them. University of Minnesota research, Professor Peter Sorensen and his colleagues are also finding that carp can be relatively easily conditioned to food or other signals. Carp are a long-lived species and seem to be able to remember events or rewards for long periods and use that information in responding to similar situations in the future. Peter is conducting simple food reward experiments to determine whether large numbers of carp can be trained to come to particular areas in a lake and then be trapped out.
We may have very different weather conditions in Minnesota and Australia, but it is still worth sharing our knowledge and finding better ways to approach our common pests.
