Feeding migration of roach, Rutilus rutilus (L.), in Lake Arungen, Norway

In the period April–July 1980 we studied the feeding migration and food of roach in a small tributary of the eutrophic Lake Årungen, south-eastern Norway. Tagging experiments revealed a tendency in roach to utilize a specific tributary both for feeding and for spawning. The mean size of roach ascending the tributary in late June and July was significantly larger than the mean size of roach spawning 1–2 months earlier, probably due to higher water discharge in July than in May and June. The experiment indicates two separately motivated migrations involving homing. The roach fed more profitably in the tributary than in the lake, both in terms of food availability and predator avoidance.