Describing the Diet of Juvenile White Sturgeon in the Upper Columbia River Canada with Lethal and Nonlethal Methods

Abstract

We describe the overall composition and prey selectivity in the diet of hatchery‐reared juvenile White Sturgeon Acipenser transmontanus in the upper Columbia River, Canada. The efficacy of two sampling methods, nonlethal gastric lavage and lethal sampling to remove stomach contents, were evaluated across different ages, size‐classes, and river sections. Gastric lavage samples were collected from 108 fish angled in October 2012 and 2013. In 2012 only, a subsample of 48 individuals were euthanized following gastric lavage, and stomach contents were collected. To describe food availability, 45 benthic grabs were collected from areas of juvenile capture. Identifiable prey taxa were recovered from 60.3% of lavage and 98% of lethal stomachs sampled. While the diet of juvenile White Sturgeon was composed of 16 diverse prey taxa, most were selected less than their availability in the river. Prey diversity in lethal samples was influenced by river section, not by fish size or age; fish in deeper, slower water consumed the highest number of prey taxa (mean = 4.6). Further, there was no significant overlap in diets among river sections, the dominant prey taxa selected differing among river sections and years. Prey in the lethal samples included 56% of the 25 total prey taxa identified, lethal included 60%, and the bottom grabs included 76%. Gastric lavage was 69% efficient at describing lethal samples. A minimum of 100 lavage samples were required to describe the diet to a level comparable to lethal sampling. Where lethal sampling is not an option, our results indicate gastric lavage, if conducted on appropriate numbers of fish, is effective at describing sturgeon diets and provides data that can be used to study the feeding ecology of threatened or endangered species. Received August 24, 2015; accepted November 24, 2015 Published online March 31, 2016

Status of White Sturgeon (Acipenser transmontanusRichardson, 1863) throughout the species range, threats to survival, and prognosis for the future

“…Juveniles (<60 cm TL) feed on tube‐dwelling amphipods, mysids, isopods, Corophium , and other benthic invertebrates such as chironomids, and on the eggs and fry of other fish species (Schreiber, ; Radtke, ; Cochnauer, ; Partridge, ; PSMFC, ; Parsley et al., ). In the upper Columbia River, diet analysis of age‐1 to age‐10 juvenile WS indicated that Mysis relicta were the primary component of the diet followed by Trichoptera nymphs; other prey items encountered (in decreasing order of abundance) were Ephemoptera nymphs, snails, Diptera, fish parts, Gammaridae, Hemiptera, and Plecoptera (Crossman et al., ). As WS grow (~60–80 cm TL), their diets diversify and they begin to eat fish (Muir et al., ; PSMFC, ).…”

Movement behaviour of endangered white sturgeon Acipenser transmontanus responds to changing environmental conditions below a dam

“…High use of the HLK Eddy for feeding (e.g. benthic prey; Crossman et al 2016) and overwintering has been identified for white sturgeon (Fisheries and Oceans Canada 2014, BC Hydro 2016). The HLK Tailrace consists of discharge from HLK and is a deep pool (10 m) that shallows (< 5 m) where it joins the ALH Tailrace.…”

Accuracy of histology, endoscopy, ultrasonography, and plasma sex steroids in describing the population reproductive structure of hatchery‐origin and wild white sturgeon

“…Sampling was conducted in both Canada and the United States, though the primary study site was located in Canada, throughout a 57-km reach of the LCR, between Hugh L. Keenleyside Dam (river kilometer [rkm] 0.0) and the United States-Canada border (rkm 57) in British Columbia, Canada (Figure 1). Sampling was divided among three zones, which were delineated by differences in discharge, available habitat, and previous data on differences in growth (BC Hydro, 2018) and diet (Crossman et al, 2016).…”