Diet and Condition of Age-0 Scaphirhynchus Sturgeon: Implications for Shallow-Water Habitat Restoration

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.

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

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The influence of depth and velocity on age-0 Scaphirhynchus sturgeon prey consumption: Implications for aquatic habitat restoration

Redspot Chub (Nocomis asper) are a keystone species in Ozark Highland streams of the Arkansas River drainage because their unique mound-building reproductive behavior facilitates recruitment of nest associates. Data contributing to an increased understanding of Redspot Chub natural history is required for the conservation of this species as it is listed as a species of concern throughout most its range. The findings presented within thoroughly describe Redspot Chub feeding ecology by documenting an ontogenetic diet shift, patterns of seasonal resource use, important prey taxa, estimates of trophic position and dietary niche breadth, as well as documenting feeding strategies at population and individual levels. Diet collections were conducted seasonally in 2018 and 2019 at four sites on Spavinaw Creek in Arkansas and Oklahoma. Logistic regression provided evidence for a previously undescribed ontogenetic diet shift, which split Redspot Chub into two functionally different species from a dietary perspective. Redspot Chub ≥ 162 mm total length (TL, RSCB) occupied a significantly higher trophic level than Redspot Chub < 162 mm TL (RSCS). In terms of caloric contribution, Ringed Crayfish (Faxonius neglectus neglectus) nearly accounted for the entire diet of RSCB, regardless of season. This specialization led to a much lower overall dietary niche breadth when compared to RSCS. Furthermore, Amundsen plots clearly depicted RSCB population specialization on crayfish. Conversely, Trichoptera were the most important prey across seasons for RSCS. Coleoptera, Ringed Crayfish, and Ephemeroptera ranked second in importance at different times seasonally. RSCS also possessed a relatively narrow niche width, but Amundsen plots exhibited a pattern where seasonally the two most important prey types were specialized on by approximately half the population, while smaller proportions of the population specialized on less commonly used prey resources. Species' diets reflect an integration of numerous ecological components; therefore, our aim was to provide a greater understanding of Redspot Chub feeding ecology that may be useful for informing future conservation assessments and management decisions.

Ontogenetic Diet Shift, Feeding Ecology, and Trophic Niches of the Redspot Chub (Cypriniformes: Cyprinidae: Nocomis asper)

Nutrient availability in prey items can have important consequences for the growth, reproduction, survival, and recruitment into adulthood of juvenile fish. For young of the year sturgeon, which ar...

Differences in macronutrient content of common aquatic macroinvertebrates available as prey for young-of-the-year Scaphirhynchus sturgeons in the lower Missouri River

Anthony P. Civiello

Papers

Are shovelnose sturgeon a valid diet surrogate for endangered pallid sturgeon during the first year of life

Diet and Condition of Age-0 Scaphirhynchus Sturgeon: Implications for Shallow-Water Habitat Restoration

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

The influence of depth and velocity on age-0 Scaphirhynchus sturgeon prey consumption: Implications for aquatic habitat restoration

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