Winter short-distance migration of juvenile fish between two floodplain water bodies of the Lower River Rhine

Abstract

During winter, large numbers of juvenile fishes (mainly roach, Rutilus rutilus L.) were observed to migrate at dawn from a floodplain lake into a connected channel, whereas they migrated in the opposite direction at dusk. The diurnal migration pattern was strongly correlated to light intensity. The total number of migrating fish decreased from autumn to spring. Ice coverage and water temperature were the only abiotic factors that affected the seasonal migration pattern significantly. Moonlight, water level, current velocity, rainfall, insolation and wind velocity did not in.uence the observed migration of juvenile fish. The results are discussed in relation to food availability, predation risk and energy conservation. © 2006 The Authors Journal compilation © 2006 Blackwell Munksgaard.