Comparison of Multipiscivore Foraging Success on Native and Invasive Prey Fish under Variable Light Intensities

Abstract

Piscivorous fishes attack and consume a variety of prey; however, few studies have examined interactions of multiple predators with multiple prey species. The situational complexity of foraging at different times of day was explored by examining the interactions of paired native predators (Burbot Lota lota or Smallmouth Bass Micropterus dolomieu) with either native (Mottled Sculpin Cottus bairdii) or invasive (Round Goby Neogobius melanostomus) benthic prey. The study allowed the comparison of a pursuit predator (Smallmouth Bass) and an ambush predator (Burbot). Trials were performed under natural relevant lighting conditions with downwelling light intensity and emission spectrum matched to the irradiance at a 10-m depth in the St. Louis River estuary during the summer at night, civil twilight, sunrise, and midmorning. Smallmouth Bass were more active and initiated 1,510 reactions that resulted in the successful capture of 61 Round Goby and 103 Mottled Sculpin, whereas Burbot initiated 475 reactions resulting in 24 successful retentions, including 9 Round Goby and 15 Mottled Sculpin. The percentage of successful retentions was greater for Smallmouth Bass (10.9%) than for Burbot (5%). Reaction probabilities to each prey differed significantly, which resulted in a two-fold increase in attacks on Mottled Sculpin compared with Round Goby within the same time period. Reaction distances for both predators did not differ regarding prey species, but Smallmouth Bass reacted from farther away than did Burbot (maximum reaction distances of 159 and 98 cm, respectively). Greater success of native predators on native prey has likely caused higher mortality on native prey populations due to greater predator success, while capturing invasive prey decreases the net energy intake.

Differences in predator-avoidance behavior between two invasive gobies and their native competitors

“…However, extrapolation of these conclusions to other Ponto-Caspian gobies must be done with care. A similar experimental study conducted on the invasive Ponto-Caspian round goby N. melanostomus showed that the native predators, the burbot ( Lota lota ) and smallmouth bass Micropterus dolomieu , hunted the round goby less efficiently than a native cottid prey species, the mottled sculpin Cottus bairdii ( Michels et al 2021 ). One of the reasons for the discrepancy between the studies may be morphological differences between the gobiids ( Jakubčinová et al 2017 ).…”

Effects of predator species, composition and light environment on prey escape behaviours of invasive and native benthic fishes

“…Prey evasion success was calculated as the inverse probability of the predator locating, attacking, capturing and retaining prey (i.e. 1-P Reaction , Michels et al, 2021), using the approach identified for prey detection by predators (O'Brien, 1979;Keyler et al, 2015Keyler et al, , 2019Richmond et al, 2004). Descriptions of each stage are detailed in Michels et al (2021), but below are brief definitions.…”

“…1-P Reaction , Michels et al, 2021), using the approach identified for prey detection by predators (O'Brien, 1979;Keyler et al, 2015Keyler et al, , 2019Richmond et al, 2004). Descriptions of each stage are detailed in Michels et al (2021), but below are brief definitions. Reactions were defined as predators orienting towards moving prey (O'Brien, 1979).…”

“…FID was measured from the midpoint of the prey body to the closest point of the predator. An escape as defined here was limited to within the maximum reactive distance of the predator at the tested light intensity, which was defined by Michels et al (2021). The number of prey fleeing during an attack (multiple individuals fleeing at the same time F I G U R E 1 Geometric breakdown of a prey escape.…”

“…Predator profile, speed and size affect prey escape behaviours (Karplus & Algom, 1981;Webb, 1984aWebb, , 1984b. As a predator approaches, the cost of remaining in a given space increases with both predator speed (Dill, 1973(Dill, , 1974Fuiman, 1993) and size (Dill, 1974;Helfman, 1986;Hurley & Hartline, 1974;Lima & Dill, 1990;Ydenberg & Dill, 1986) as closer interactions often result in prey capture (Michels et al, 2021). Predators are classified into two broad categories; ambush lie-in-wait predators versus active search predators.…”