Abstract

All Canadian lake sturgeon (Acipenser fulvescens) populations are listed under the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) due to their complex life history, loss of habitat and negative interactions with anthropomorphic activities. Lake sturgeon diets vary considerably across their range and depend on the local benthic invertebrate fauna, substrata, and competition with congener species. Hence, determining population-specific prey assemblages is a vital contribution to effective conservation efforts. We used carbon and nitrogen stable isotopes to identify lake sturgeon prey preferences for juvenile (<100 cm) and adult (>100 cm) age classes and their trophic niche in the Saskatchewan River, SK, Canada. In this system, lake sturgeon were the top predator within the benthic food web with no direct competition for preferred prey items from congener species. Their diet was dominated by crayfish (49.1± 6.4%) and snails (36.3 ± 5.5%), with no significant differences between age classes. Furthermore, lake sturgeon favoured deep rocky pools throughout the river; a habitat where crayfish and snails are typically found. Therefore, conservation efforts should be directed at preserving these habitats for the residing benthic invertebrate community, and the lake sturgeon’s ability to access them.

Highlights

  • Sturgeon, Acipenseridae, is one of the most prevalent and charismatic families of fishes worldwide, inhabiting estuaries, rivers, near-shore oceanic environments and inland seas of the northern hemisphere [1]

  • The study area encompassed a section of the Saskatchewan River, Saskatchewan, Canada spanning from the confluence of the North Saskatchewan and South Saskatchewan Rivers (Latitude: 53.235187; Longitude: -105.08294779031895) to Codette Reservoir, formed by the Francis-Finley dam in Nipawin, Saskatchewan, Canada (Latitude: 53.31808; Longitude: -104.04179185266574) (Fig 1)

  • Mean δ13C values in 2009, 2010, and 2011 were -24.7 ± 1.1‰, -24.9 ±1.1‰, and -26.2 ± 1.5‰, respectively, with 2011 values significantly depleted in δ13C relative to the previous years (p < 0.05)

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Summary

Introduction

Acipenseridae, is one of the most prevalent and charismatic families of fishes worldwide, inhabiting estuaries, rivers, near-shore oceanic environments and inland seas of the northern hemisphere [1]. Of the 25 extant species, white sturgeon (Acipenser transmontanus [Richardson, 1836]), green sturgeon (Acipenser medirostris [Ayres, 1854]), Atlantic sturgeon (Acipenser oxyrhynchus [Mitchill, 1815]), shortnose sturgeon (Acipenser brevirostrum [Lesueur, 1818 non Heckel, 1836]), and lake sturgeon Saskatchewan River lake sturgeon diet preferences and analysis, decision to publish, or preparation of the manuscript

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