Dietary assessment of age-0 pallid sturgeon and shovelnose sturgeon: implications for surrogacy

Abstract

Validation is critical when considering potential surrogates for endangered species research. The pallid sturgeon Scaphirhynchus albus is federally endangered in the USA, whereas the congeneric shovelnose sturgeon S. platorynchus is common. Inadequate food availability during early life history is a hypothesized factor limiting recruitment of pallid sturgeon in the lower Missouri River, USA, and an established surrogate relationship with shovelnose sturgeon would dramatically expedite research efforts related to potential food limitation. During 2018, 4 exogenously feeding pallid sturgeon larvae were captured concurrently with multiple shovelnose sturgeon, providing a critical opportunity to evaluate diet surrogacy using individuals captured from the same locations. We found that both species primarily consumed ephemeropterans but chironomids were also frequent prey. Over 90% of the pallid sturgeon prey items belonged to taxa also consumed by shovelnose sturgeon. Additionally, we often observed high diet similarity between these congeners. As for total prey weight, pallid sturgeon consumption was similar or higher compared to similarly sized shovelnose sturgeon. Although the sample size was limited, this study supports the hypothesis that larval pallid sturgeon are capable of finding food in the lower Missouri River and exhibiting diet similarity with shovelnose sturgeon. We also provide the first quantification of prey weight for wild-produced larval pallid sturgeon, which consumed relatively large amounts of prey in the wild during the critical transition from endogenous to exogenous feeding.

Floodplain connectivity and age‐0 sturgeon prey consumption in the lower Missouri River

“…These results are consistent with most of the previous diet studies conducted in mainstem habitats of the LMOR (Civiello et al, 2018;Gosch et al, 2016;, but additional work has suggested that age-0 sturgeon may be able to feed opportunistically depending on prey availability. For example, Gosch, Gemeinhardt, Civiello, Harrison, and Bonneau (2019) Interestingly, this study is the first published report from the LMOR documenting empty stomachs in large age-0 sturgeon (50-88 mm). This was unexpected because these individuals were captured on the floodplain and empty stomachs in the LMOR were previously restricted to small individuals ≤21 mm (Civiello et al, 2018;Gosch et al, 2016).…”

“…Subsequently, shovelnose sturgeon recruitment appears to be occurring in the LMOR. For example, Steffensen, Stukel, and Shuman (2014) consume similar prey types (Gosch et al, 2018(Gosch et al, , 2019 in comparable amounts (Gosch et al, 2019)…”

Macroinvertebrate drift patterns in the Mississippi and Missouri Rivers: Implications for Scaphirhynchus sturgeon conservation efforts

“…The shovelnose sturgeon tends to be smaller in size and have a shorter lifespan than pallid sturgeon (Tranah, Campton, & May, 2004). Macroinvertebrates are important prey for both shovelnose sturgeon and pallid sturgeon, notably in early life stages (Gosch, Gemeinhardt, Civiello, Harrison, & Bonneau, 2019;Hay, Franti, Marx, Peters, & Hesse, 2008;Rapp, 2014;Sechler et al, 2012;Seibert, Phelps, Tripp, & Garvey, 2011;Wanner, Shuman, & Willis, 2006).…”

“…Shovelnose sturgeon and pallid sturgeon survival and growth may be influenced by macroinvertebrate prey availability for larval sturgeon in the lower Missouri River and MMR (Gosch et al, 2016;Gosch et al, 2019;Jacobson et al, 2016). Previous studies have evaluated and accepted the use of shovelnose sturgeon as diet surrogates for pallid sturgeon (Braaten, Fuller, & McClenning, 2007;Sechler et al, 2012;Harrison, Slack, & Killgore, 2014;Civiello et al, 2018;Gemeinhardt et al, 2019).…”

“…Previous studies have evaluated and accepted the use of shovelnose sturgeon as diet surrogates for pallid sturgeon (Braaten, Fuller, & McClenning, 2007;Sechler et al, 2012;Harrison, Slack, & Killgore, 2014;Civiello et al, 2018;Gemeinhardt et al, 2019). Larval and adult sturgeon feed on Diptera, Ephemeroptera, and Trichoptera (Wanner et al, 2006, Seibert et al, 2011Sechler et al, 2012, Rapp, 2014Gosch et al, 2018Gosch et al, , 2019. Braaten et al (2012) further determined that young of year pallid sturgeon diets consisted primarily of Diptera larvae and pupae and Ephemeroptera nymphs.…”