One sophisticated yet simple way to track movements of carp is to use small electronic tags called PIT tags. The style we use are about the size of a tic-tac and sit just inside the body cavity of the fish. Since they are so small and implanting them is minimally invasive, we can passively track the movement of hundreds of fish easily from young of year to full-sized adults. As the fish swims near an antenna installed in strategic locations, it records the individual fish ID and gives it a time stamp. After data analysis, we can determine how many tagged fish have passed over the antenna (typically located in a stream) and when they moved past it.
Collaborating with engineers, we can also use this method to test the efficiency of physical or electric barriers intended to impede the movement of carp.