Chapter 15: Walleye Functional Response: Implications for the Analysis of Interactions between Walleye and Age-0 Yellow Perch in Oneida Lake
Lars G. Rudstam, John R. Post, and John L. Forney
A predator’s functional response is the feeding rate of a predator as a function of prey abundances (Solomon 1949; Holling 1959). This function is central to understanding predator–prey interactions and connects behavioral ecology and population dynamics (Fryxell and Lundberg 1998). There are several theoretical derivations and numerous empirical studies of the functional response in a variety or predator–prey systems (Abrams and Ginzburg 2000; for a review of various functional response models, see Jeschke et al. 2002). Holling’s (1959) original formulation is based on a time budget. A predator is assumed to either be able to search for or to handle prey, not both. This leads to an asymptotic response where the maximum feeding rate is reached when the predator search time is minimized and feeding rate is only limited by prey handling time (types II and III functional response, Holling 1959). But very few predators are likely to be handling time limited. Jeschke et al. (2002) found only three handling time limited predators in the literature: a host-parasitoid system, a flagellate feeding on bacteria, and a drilling gastropod feeding on mussels. The vast majority of predators, including fish, are digestion time limited and digestion time should therefore be included in their functional responses.