Abstract
The northern pike is an important top predator in lakes. Its predation may cause trophic cascades, propagating throughout the food web. It may thereby affect lake ecosystem composition, and ultimately e.g. water quality, fisheries productivity and biological richness. Pike are also cannibalistic and kleptoparasitic (stealing food from each other). Falling victim to such interactions should be costly, and they should thus be avoided. Interaction risk should increase with increasing size and decreased genetic relatedness of opponent, and increase with increasing movements in the individual, where larger individuals are allowed greater freedom of movement, which would all structure the pike population distribution. These factors would affect the top-down cascades, since they could in different combinations increase pike foraging efficiency or create refuges for prey. This proposal focuses on these individual pike behaviours, that are crucial keys to the understanding of the complex interactions found in lake ecosystems, that may determine e.g. shallow lake water quality, productivity and species composition.
Sweden