Functional Feeding Response of Piscivorous Fishes and Implications in Multispecies and Ecosystem Models

Abstract

The functional feeding response forms of piscivorous fishes used in multispecies and ecosystem modeling have been questioned because they were mostly conjectural or solely based on laboratory studies. Here we investigate the functional feeding response of seven species of piscivorous fishes on four species of their prey from the northeast US continental shelf using field data that spans thirty years.  Our study confirmed that Holling’s type II and type III functional responses are the most common functional responses for piscivorous fishes in this region. However, our analyses also revealed that differences exist between piscivorous fishes’ functional responses and therefore, combining functional responses of piscivores is probably not appropriate in multispecies and ecosystem modeling.  In the absence of specific predator-prey functional responses, we suggest that for cruising, actively attacking predators a type II functional response is slightly preferable; for a sedentary, ambush predator a type III functional response is slightly preferable; at low prey densities for a generic fish predator a type III functional response should be used; and at moderate to high prey densities, either should work sufficiently.  Because we have shown that the functional response of a particular predator to individual prey species varies, these relationships must be further evaluated as we continue to develop and employ multispecies and ecosystem modeling. 

 Keywords: Piscivorous fishes, Functional response, Northeast US continental shelf