Behavior of pike (Esox lucius L.) > 50 cm in a turbid reservoir and in a clearwater lake

Pike from two different waters were radio-tagged and released immediately u pon recovery In Bygholm Reservoir 19 pike (52-72 cm) and in Lake Ring 15 pi ke (53-77 cm) were tagged in late February and early March. Bygholm (58 ha) is a shallow eutrophic reservoir and Ring (22 ha) is a natural mesotrophic lake. The positions of the tagged fish were recorded through weekly tracki ngs and a number of 3-day tracking sessions during a 9-month period. Diel a ctivity patterns, home range sizes and habitat utilization by pike was comp ared between the reservoir and the lake. The pike in the lake occupied larg er areas than the pike in the reservoir and were less associated with veget ation. In both waters pike were found more often in, or close to, vegetatio n during summer than during winter. No difference in average movement of pi ke was seen between the waters, but pike were more stationary in the reserv oir than in the lake. There was no difference in the level of movement betw een different times of the day, but the diel rhythm of the pike changed sig nificantly over the year. There were large behavioral differences between p ike in the lake and in the reservoir and even more variation between indivi duals within each population.