Some interesting parts of the study IMO.

Table 4
Literature review of study piscivore gape-limits and maximum ingested prey size estimates.

Predator taxon Prey taxon Study Type Estimate Type % Body Length Reference


Largemouth Bass All Prey Field survey Max. model 30–35% Goldstein [58]

Largemouth Bass All Prey Field survey 90th %tile value 33% Pierce, Sexton [57]

Largemouth Bass All Prey Field survey Max. value 71% Pierce, Sexton [57]

Largemouth Bass Bluegill Gape-limit Max. model 34–35% Lawrence [56]

Largemouth Bass Gizzard Shad Gape-limit Max. model 34–49% Lawrence [56]

Largemouth Bass Largemouth Bass Gape-limit Max. model 44–58% Lawrence [56]c


Early optimal foraging (or diet) theory predicted that predators optimally forage by selecting prey that maximizes energy gain while minimizing handling time [2, 10, 17–19]. Optimal foraging theory, therefore, predicts that IPmax and IP50 should increase linearly with predator size [10] and is limited only by gape (i.e., gape-limit; [21]). While this has served as a foundation for gape-limitation research, studies over the last quarter century have shown that piscivore predation does not follow this pattern as prey mobility may influence both encounter rate and capture efficiencies [21, 22, 48, 52–54]. Furthermore, energetically favorable large prey fishes are often relatively scarce in ecosystems [48]. While piscivores become more effective predators with size due to increased swimming speed, burst capabilities, and visual acuity, prey fishes similarly become more effective at avoiding predation with size [2, 48, 55]. Our findings support these developments in optimal foraging theory that suggest foraging success on mobile prey is not simply a function of gape limitation and handling time, but also of search time, encounter rate, opportunity, and prey behavior [52, 53].


A common approach to estimate IPmax is the gape-limit method (Fig 2, Line c; Table 4; e.g., [56]). However, this method assumes predator mouth size is the only determinant of prey size and does not account for prey availability, prey behavior, handling time, capture success, or competition, which often results in overestimated IPmax for larger individuals.

We acknowledge that our results have limitations (e.g., low sample sizes for crappie, smallmouth bass, and rock bass; northern pike observations from only two lakes; and a lack of information on prey fish community size structure available in the ecosystem) and, therefore, stress that these are “realized” prey lengths, not “preferred” prey lengths.

Furthermore, while it has been shown that the size distribution of prey fishes available in the environment do not reflect those observed in the diet [50], we recommend future analyses compare the distribution of prey total lengths found in diets to the distribution of length observed in the ecosystem. Despite potential shortcomings, examining predator-prey total length relationships for a variety of taxa across multiple lakes, as in our study, provides an empirical basis for assessing how predation can structure or influence populations, communities, and aquatic ecosystems.

Last edited by ewest; 12/07/18 01:13 PM.