The movements of pikeperch in a shallow reservoir

The movements of 12 female (62–74 cm) and eight male pikeperch (55–64 cm) radiotagged in early March 1997 in the shallow and turbid Bygholm Reservoir, peaked during the summer, but all fish were also active during the winter. Females moved more than males and their activity was correlated with water temperature. Rate of movement was correlated positively with body size for both male and female pikeperch. During the breeding season (April–May) males became stationary for 14–47 days. Spawning sites, inferred from movements of males, were at depths of 2·0–2·5 m on hard substrata, mainly gravel in areas with many submerged trees and shrubs. Males tended to use the same spawning site the next year. Diel activity pattern varied seasonally but activity was highest from 1800 to 2400 hours.