Age‐0 Sturgeon Accessibility to Constructed and Modified Chutes in the Lower Missouri River

Abstract

AbstractShallow‐water habitat is hypothesized to provide nursery habitat for young fish. The construction of side‐channel chutes to restore shallow‐water habitat is common in the lower Missouri River; however, a recent adaptive management strategy document (developed by a multiagency, multidiscipline team), as well as previous research, has suggested that the accessibility of chutes to age‐0 Scaphirhynchus spp. (sturgeon hereafter) may be limited. Access is a critical prerequisite for young fish utilizing chute habitat; thus, we investigated chute‐specific accessibility for age‐0 sturgeon at seven chutes (constructed and natural). Age‐0 sturgeon were capable of accessing most chutes; however, accessibility appeared limited at sites with highly restrictive inlet structures. Our results suggest that future consideration of chute inlet designs that meet authorized Missouri River purposes while providing improved fish access is warranted. Additionally, capture sites for exogenously feeding age‐0 sturgeon were usually deeper (>1.5 m) and faster (>0.5 m/s) than sites without sturgeon in chute and adjacent main‐stem habitats. This finding is consistent with previous research that suggests that slow and shallow habitats may not be used by age‐0 sturgeon as frequently as other habitat types in the lower Missouri River.Received June 4, 2014; accepted September 24, 2014