River deltas have a high potential for biodiversity and thriving fish populations. No wonder, the Dutch delta lakes, rivers, streams and canals are much appreciated by recreational and commercial fishers and natural environmentalists. Solid knowledge of how freshwater ecosystems function for a diverse fish fauna is essential in supporting management and wise use of our precious waters. This includes an understanding of behaviour and habitat use of fish. Wageningen Marine Research develops knowledge on the influence of natural processes and major human interventions on the behaviour of fish, their habitats and wise use of fish stocks.