Multispecies functional responses reveal reduced predation at high prey densities and varied responses among and within trophic groups

• Published in: Fish and fisheries (Oxford, England) England), 2020-09, Vol.21 (5), p.891-905
• Main Authors: Smith, Brian E., Smith, Laurel A.
• Format: Article
• Language: English
• Subjects: Bayesian inference; Cephalopod fisheries; Community structure; continental shelf; Continental shelves; Decision making; Density; Ecosystem management; Ecosystem models; Environment models; Feeders; feeding guilds; Fish; Fisheries management; functional feeding response; Interspecific relationships; Marine ecosystems; Marine fish; Marine fisheries; Marine molluscs; Northwest Atlantic; Piscivores; Plankton feeders; Predation; Predator-prey interactions; Predators; Prey; Resource management; Satiety; Sustainability; trophic interactions; Trophic relationships
• ISSN: 1467-2960; 1467-2979
• DOI: 10.1111/faf.12468

Understanding predator–prey interactions is critical for marine fisheries and ecosystem management as they shape community structure, regulate prey populations and present energy demands critical for community sustainability. We examined multispecies functional responses of 17 fishes (48 predator‐size combinations) spanning piscivores, planktivores and benthivores for the northeast US continental shelf. Similar to previous work, linear relationships between predation and prey density (Holling type I response) were not supported, since model estimates of handling time were greater than zero for the prey considered. Instead, a clear majority of the predators sampled were Holling type III feeders (sigmoidal; prey switching or learning). For piscivores, nearly all responses were Holling type III with the exception of one being Holling type II (hyperbolic; satiation). Planktivores and benthivores exhibited a combination of type IV (feeding confusion at high prey density) and Holling type III responses. The relationships were predator‐ and prey‐dependent, which is counter to assumptions that are often made of trophic groups. Decreased predation at high prey densities (type IV response) present among planktivores and benthivores suggests an overestimation of predation can occur if ignored. This contrasts with fish and squid prey which primarily invoked a Holling type III response. Functional responses are key to modelling trophic interactions for multispecies and ecosystem models. By refining these inputs in a multispecies context with empirical data, we can advance our understanding of whole‐shelf ecology and improve decision‐making tools for resource management.