Sensory Mechanism and Selective Advantage for Diel Vertical Migration in Juvenile Sockeye Salmon, Oncorhynchus nerka

Abstract

Diel vertical migrations are commonly undertaken by juvenile sockeye salmon within pelagic lake nursery environments. Data from hydroacoustic surveys in British Columbia lakes are used to compare predictions from sensory mechanism and selective advantage theories for diel vertical migration with the performance of the animals under field conditions. The observations suggest that light and temperature controlled juvenile sockeye day and night depth positions respectively. A multifactor hypothesis, which interprets the migration as a three-way compromise between foraging, predator avoidance, and the optimization of nocturnal metabolic efficiency, provides the most realistic explanation for the selective advantage of the behavior.