Planktivore Preference by Prey Size

The reactive field volume model of prey encounter was shown to give a close approximation to the apparent size model of prey encounter rate for prey size distributions consisting of many prey types. The two models of prey encounter give almost identical predictions for the Lake Washington zooplankton community. The prey encounter models do not account for observed patterns of prey selection by Lake Washington juvenile sockeye salmon. This suggests an active preference for large nonevasive prey. This preference is dynamic. Small as well as evasive prey are pursued and eaten at times in the year when the large nonevasive prey are rare or absent from the water column.