Table 1.
Summary of compiled dataset sample sizes, location of lakes, and collection years.
Table 2.
Predator and prey total length (TL, mm) transformations (trans.) and quantile regression derived equations.
Fig 1.
Predator and prey fish total lengths (mm) and quantile regression models.
Piscivores evaluated include muskellunge (Esox masquinongy; n = 473), northern pike (Esox lucius; n = 2,233), walleye (Sander vitreus; n = 18,102), largemouth bass (Micropterus salmoides; n = 1,486), smallmouth bass (Micropterus dolomieu; n = 380), and a grouped ‘crappie’ category (P. nigromaculatus and P. annularis; n = 317). The 1st, 5th, 50th, 95th, and 99th percentile regressions are shown as gray lines. When the appropriate taxonomic resolution and sample size was available, prey fishes were categorized as having fusiform (black points) or laterally compressed (gray points) body shape, otherwise prey fish body shape was unclassified (open points). The 5th, 50th, and 95th percentiles of predator total lengths are shown at the top of each plot and correspond to the range of lengths modeled in Figs 2 and 3 as well as the density distributions in Fig 4.
Table 3.
IP50 (50th percentile regression) and IPmax (99th percentile regression) model coefficients.
Fig 2.
The relative maximum ingested prey total length (percent of predator total length) consumed across predator total length.
Piscivores evaluated include muskellunge (Esox masquinongy), northern pike (Esox lucius), walleye (Sander vitreus), largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), and a grouped ‘crappie’ category (P. nigromaculatus and P. annularis). The relative IPmax (99th percentile regression) is shown from the 5th to 95th percentile of observed predator total lengths, which are noted on the top axes of Fig 1. When applicable, we estimated relative IPmax for different prey body shapes: fusiform (dashed lines) and laterally compressed (dotted lines). Literature derived data are for a field survey of all prey [24]; b field survey of gizzard shad (Dorosoma cepedianum) as prey [45], c gape-limit for largemouth bass as prey [46], and d field survey of Cyprinids as prey [14]. Additional literature derived estimates are reported in S3 Appendix.
Fig 3.
Central tendency of relative ingested prey total length (percent of predator total length) consumed across predator total length.
Piscivores evaluated include muskellunge (Esox masquinongy), northern pike (Esox lucius), walleye (Sander vitreus), largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), and a grouped ‘crappie’ category (P. nigromaculatus and P. annularis). The relative IP50 (50th percentile regression) is shown from the 5th to 95th percentile of observed predator total lengths, which are noted on the top axes of Fig 1. When applicable, we estimated relative IP50 for different prey body shapes: fusiform (dashed lines) and laterally compressed (dotted lines).
Fig 4.
Kernel density distributions of model estimated consumed prey total lengths (mm).
Distributions estimated for the 5th (dotted line), 50th (dashed line), and 95th (solid line) percentile of predator total lengths (TL; mm). Piscivores evaluated include muskellunge (Esox masquinongy), northern pike (Esox lucius), walleye (Sander vitreus), largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), and a grouped ‘crappie’ category (P. nigromaculatus and P. annularis). The predator total lengths correspond to the top axes of Fig 1. Kernel densities at a given predator total length were derived by estimating prey total length with percentile regressions of every percentile from the 1st to the 99th (Table A in S2 Appendix). The modes of the 5th, 50th, and 95th percentile kernel density distributions are shown along the bottom axis as gray circles, triangles, and diamonds, respectively.
Fig 5.
The deviation in predicted prey total length (TL) across sample size.
We resampled our largest dataset (walleye; n = 18,102) without replacement generating a range of smaller sample sizes and evaluated how sensitive prey total length predictions are to the number of observations used to develop the model. The 1st, 50th, and 99th percentile regression (i.e., the minimum, median, and maximum ingested prey total length models; IPmin, IP50, and IPmax, respectively) was reanalyzed at each reduced sample size and the predicted prey total length consumed at the 1st, 50th, 99th percentiles of predator total length (131, 483, and 682 mm, respectively) was estimated. These estimates were compared to the model-estimated prey total length derived with the full dataset (n = 18,102) to determine the deviation as sample size is reduced. This procedure was repeated 1,000 times at each sample size to calculate the mean deviance (thick black line), ± 1 standard deviation (SD; dark gray polygon), and ± 2 standard deviations (light gray polygon). Shown with ± 5 mm as thin dashed lines.
Fig 6.
Predator-prey body-mass ratios (log10) across predator and prey taxa.
Gray boxes are data from Brose et al. [43] with "Freshwater ectotherms" reported in Brose et al. [42]; the data were further subsetted into only freshwater fish as predators ("Freshwater fishes") and freshwater fishes preying on fishes ("Freshwater piscivores"). White boxes represent data from our study. Shown with sample size (below); groups with the same letter are not significantly different at the p≤0.05 level. Box plots are shown with medians, first and third quartiles, and a range of 1.5 times the interquartile range. Outliers beyond the range are represented as points. Fish lengths were converted into mass using the general allometric relationship for fishes as reported in Brose et al. [43].
Table 4.
Literature review of study piscivore gape-limits and maximum ingested prey size estimates.
Fig 7.
A management application minimizing vulnerability of stocked prey fish to predation in a Utah reservoir.
The kernel density distribution of model predicted prey total lengths (mm) consumed by a smallmouth bass population (inset) in Big Sand Wash Reservoir, UT. Shown with percentiles of the prey total lengths consumed on the top axis.