Predation on Early Life Stages of Lake Sturgeon in the Peshtigo River, Wisconsin

Abstract

Mortality of early life stages can limit recruitment of fishes, and understanding the impacts of various sources of mortality has long been a goal of fisheries management. The impacts of predation on lake sturgeon Acipenser fulvescens are not well understood. The objective of this study was to identify and quantify sources of predation that affect lake sturgeon eggs, larvae, and age‐0 juveniles in the Peshtigo River, Wisconsin, during 2006 and 2007. Egg bags were used to assess the rate of lake sturgeon egg consumption by crayfishes Orconectes spp. Potential piscine predators on eggs, larvae, or age‐0 juveniles were captured using fyke nets, gill nets, hoop nets, and electrofishing for analysis of stomach contents. Crayfish consumed lake sturgeon eggs at an average rate of 9.4 eggs/d, and the population of crayfish within the lake sturgeon spawning habitat consumed an estimated 300,000 eggs during the incubation period. Numerous fish species were observed consuming lake sturgeon eggs, and piscine predators likely consumed most eggs that settled on the surface of the substrate. Within 862 predator stomachs, only a single lake sturgeon larva was observed, and there was no evidence of predation on age‐0 juveniles. These results suggest that predation could limit recruitment at the egg stage, but it does not appear to be limiting to the larval and age‐0 juvenile life stages in the Peshtigo River.

Lethal and non-lethal effects of predation by native fish and an invasive crayfish on hatchery-reared age-0 lake sturgeon (Acipenser fulvescensRafinesque, 1817)

“…Our results show that rates of predation on the juveniles by fish predators were low and similar to results documented by both Caroffino et al. () and French et al. ().…”

Review of a species in peril: what we do not know about lake sturgeon may kill them

“…Less understood is the significant variation in larval success that can exist between sites on a single river or at a single sight over several years (Benson et al 2006;Kempinger 1988;LaHaye et al 1992). Nilo et al (1997), Verdon et al (2013), Shaw et al 2012, and Caroffino et al (2010a, 2010b found that year class strength is determined in the first few months of life by climate, hydrological conditions, and predation and is highly variable between years and sites. Duong et al (2011a) found that some of this variation could be explained by environmental variables, maternal effects, and spawning time.…”

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

“…Lake sturgeon larvae are susceptible to predation by a variety of predator taxa, including fishes ) and crayfish (Crossman 2008). Research has quantified egg predation, but information on losses due to predation during the larval stage is lacking (Crossman 2008;Caroffino et al 2010b). Predation has been a major factor affecting recruitment of other sturgeon species (Parsley et al 2002;Steffenson et al 2015), and may be an important factor contributing to the lack of natural lake sturgeon recruitment.…”