Group foraging versus solitary foraging efficiency in piscivorous predators: the perch, Perca fluviatilis, and pike, Esox lucius, patterns
Publication Type: |
Journal Article |
Year of Publication: |
1992 |
Authors: |
Peter Eklöv |
Publication/Journal: |
Animal Behaviour |
Keywords: |
fish, foraging strategies |
ISBN: |
0003-3472 |
Abstract:
A predator’s foraging strategy is generally described as either a sit-and-wait or an actively searching strategy. Two different behaviour patterns, often associated with these strategies, are territorial behaviour for a sit-and-wait predator, and group foraging behaviour for an actively searching predator. In a pond experiment, the effect of predator density on the efficiency of a sit-and-wait predator, pike, and an actively searching predator, perch, was tested. The foraging efficiencies of these two predators were predicted to be density-dependent since perch is a social species with its efficiency enhanced by mutualistic interactions, while pike is a territorial species with its efficiency reduced by competitive interactions. The predators were stocked at two densities (one or five individuals) in enclosures containing the same prey densities (75 individuals of juvenile perch). The behaviour of predators and prey, prey mortality and predator growth were studied. As expected, swimming speed and move frequency were significantly higher for perch than for pike. In the five-pike treatment, predator activity (swimming speed and move frequency) was highly size-dependent with the large pike both swimming faster and moving more frequently than the small pike. The activity levels of the pike were also reflected in the area used, which was larger for the large pike. Perch at both densities and the large pike used similar areas. As hypothesized, the growth rate of the predators corresponded to their foraging strategies. The growth rate of group foraging perch was higher than that of single perch and pike in both density treatments. In the single predator treatments, pike grew better than perch. In contrast to perch, the single pike grew more than the five pike together.