For a planned relocation of carp from lake Oostvaardersplassen to lake Markermeer in the Netherlands, goals under the Water Framework Directive required us to monitor the dispersal of these animals after release throughout the lake and adjoining waters. For 1.5 years, a network of hydrophones has been in operation to monitor the migration of carp in lake Markermeer. In total, 70 carp are equipped with a VEMCO v13 transmitter and 20 hydrophones have been placed.