Populations of pike and perch have shown marked declines along the Swedish Baltic Sea coast. One of the main causes of these declines is the dramatic increase of three-spined stickleback. The stickleback is a small species of fish that reproduces quickly and shows a good appetite for the eggs and larvae of pike and perch. Through this predation, it has knocked out local populations of pike and perch, especially in the outer archipelago. As the shift has spread successively from bay to bay, it has been nicknamed ‘the stickleback wave’.