Selective Predation by Three Esocids: The Role of Prey Behavior and Morphology

Abstract

We documented differential vulnerability of fathead minnows Pimephales promelas, gizzard shad Dorosoma cepedianum. and bluegills Lepomis macrochirus to predation by muskellunge Esox masquinongy. northern pike E. lucius. and tiger muskellunge £". masquinongy x E. lucius in a 700-L tank. Individual esocids (150-225 mm in total length) were combined with singlespecies groups (N = 15) of optimal-sized prey (25-30% of predator length for bluegills, 37-43% for fathead minnows, and 30-36% for gizzard shad). Capture ability did not differ among esocids; however, mean captures per strike were higher for fathead minnow (0.67) and gizzard shad (0.78) than for bluegill (0.14). Morphology and antipredatory behavior, unique to each prey species, contributed to this differential vulnerability. In the field, we introduced equal numbers and similar sizes of these esocids into two systems, one with centrarchid prey and one with both centrarchid and gizzard shad prey. As predicted from laboratory work, esocids ate fewer prey and grew more slowly when centrarchids were the only prey than they did when gizzard were available. In a third reservoir, containing bluegills and gizzard shad, esocids strongly preferred gizzard shad over bluegills. To maximize growth and survival, esocids should be stocked in systems with soft-rayed or fusiform prey, such as cyprinids or shad, rather than in centrarchid-dominated systems.Muskellunge Esox masquinongy. northern pike E. lucius. and their hybrid, tiger muskellunge E.

An experimental approach to determine esocid prey preference in replicated pond systems

“…These rates were also similar to those found by Lepak et al (2012) using a similar study design (pond enclosures) in which northern pike consumed approximately 0.6 rainbow trout per day over the course of a 44 d experiment. Although esocids consume a variety of prey, northern pike, muskellunge, and tiger muskellunge have been found to prefer fusiform, soft-rayed species with high energy density relative to other species (Wahl and Stein 1988); thus, these esocid species may not be effective for controlling abundant, unwanted forage fish when other, more preferred prey species are present (Beyerle andWilliams 1968, Wahl andStein 1988).…”

Assessment of the Fishery Improvement Opportunities on the Pend Oreille River: Recommendations for Fisheries Enhancement: Final Report.

“…This suggests that the pike may preferentially prey on the trout and whitefish in the Pend Oreille River, which could be disastrous to the already threatened bull trout and cutthroat trout populations. In addition, many studies (Beyerle and Williams 1968;Coble 1973;lnskip 1982;Wahl and Stein 1988) found that northern pike are not effective predators and do not prefer spiny, laterally compressed fish (pumpkinseed and bluegill). Anderson and Schupp (1986) speculated that the reduction of yellow perch through northern pike predation allowed bluegill numbers to increase.…”

Do cannibalistic fish forage optimally? An experimental study of prey size preference, bioenergetics of cannibalism and their ontogenetic variations in the African catfishHeterobranchus longifilis

“…On the other hand, their absolute energy content is low, so the net energy gain per unit of time can be less than for big a Corresponding author: etienne.baras@ird.fr prey, depending on food search time and energy invested into foraging (e.g., Jobling and Wandsvik 1983;Dos Santos et al 1993). These traits account for why the optimal or preferred predator:prey size ratios vary between predatory species with contrasting mouth dimensions (Mittelbach and Persson 1998) and further depend on the predator's size (Werner and Gilliam 1984) or social status (MacLean et al 2003), as well as on prey morphology (Scharf et al 1998), behaviour (Wahl and Stein 1988) or density, which altogether govern its probability of encountering predators (for a recent review, see Giacomini et al 2013).…”