Effects of changes in alternative prey densities on predation of drifting lake sturgeon larvae (Acipenser fulvescens)

Abstract

Predator-prey interactions including prey switching, predator swamping, and size-selectivity are important in maintaining multi-species systems. In fishes, early life stages are often recruitment bottlenecks due to high mortality partially caused by predation. High mortality is of particular concern for threatened species such as lake sturgeon (Acipenser fulvescens). Effects of different relative prey densities were examined using two predatory fishes [rock bass (Ambloplites rupestris) and hornyhead chub (Nocomis biguttatus)] and two density treatments of three prey [lake sturgeon, mayflies (Family: Heptageniidae), and suckers (Family: Catostomidae)]. Treatments consisted of prey introduced to predators in a series of pulses 30 min apart. In the initial low-density treatment, predators were offered prey at a pulse of prey at a 13:13:4 ratio of mayfly, suckers, and lake sturgeon, and a second pulse with a 1:1:1 prey ratio during the second pulse. In the equal-density treatment prey numbers were equivalent during both pulses. Larval sturgeon survival, predator preference, and size selection were measured for each trial. Lake sturgeon were the least preferred prey species while mayflies were positively selected. Hornyhead chub preference for lake sturgeon was higher in the equal-density treatment than in the low-density, indicating initial prey availability affected predator foraging behaviour. High densities of preferred macroinvertebrate prey could protect threatened lake sturgeon larvae from predation.

Atlantic sturgeon ( Acipenser oxyrinchus oxyrinchus Mitchill, 1815) early life stage consumption evidenced by high‐throughput DNA sequencing

“…If ATS early life stages were highly selected for by Blue Catfish, we would expect that at least a minimal amount of consumption would have been detected in the James River (Moran et al., 2016; Schmitt, Peoples, Castello, et al, 2019). With exception of Duda and Kapusta (2019), sturgeon early‐life stages typically were not selected for if alternative prey choices were available (French et al., 2010; Gadomski & Parsley, 2005b; Kynard & Horgan, 2002; Warniak et al, 2017).…”

Response in Growth, Scute Development, and Whole-Body Ion Composition of Acipenser fulvescens Reared in Water of Differing Chemistries

“…In Lake Sturgeon, calcium is utilized to produce defensive dorsal scutes, which are mostly made up of calcium-based minerals, most likely hydroxyapatite, with substantial phosphate and carbonate content [ 19 ]. When they are still developing, Lake Sturgeon rely on their scutes for protection [ 20 ]. For hatchery-reared Lake Sturgeon, stocking survival is thought to be associated with fish size [ 21 ]; fish are therefore reared to a relatively large size (>10 cm total length) in the hatchery prior to release.…”

Rainbow Darter (Etheostoma caeruleum, Storer, 1845) predation on early ontogenetic stages of Lake Sturgeon (Acipenser fulvescens, Rafinesque, 1817)

“…Predation is a leading determinant of annual recruitment of fishes in many ecosystems (e.g., Bailey & Houde, 1989;Leggett & DeBlois, 1994), including lake sturgeon (Acipenser fulvescens, Rafinesque, 1817;Peterson, Vecsei, & Jennings, 2007;Waraniak, Valentine, & Scribner, 2017). As with many fishes, lake sturgeon exhibit a type III survivorship curve (Deevey Jr., 1947) characterized by high mortality in the early life stages (Caroffino, Sutton, Elliott, & Donofrio, 2011;Forsythe, Scribner, Crossman, Ragavendran, & Baker, 2013;Nichols et al, 2003).…”

“…During the larval drift stage, lake sturgeon emerge from the substrate, disperse downstream, and begin to feed exogenously. The magnitude of predation risk facing lake sturgeon varies according to the timing of spawning and larval drift, availability of co-distributed prey, and taxonomic composition of piscine predators (Waraniak, Valentine, et al, 2017). Quantifying these relationships in complex riverine systems is critical to the management of threatened and endangered species (e.g., Crossman et al, 2017;Waraniak, Blumstein, et al, 2017;Waraniak et al, 2019).…”