Habitats of Age‐0 Sturgeon in the Lower Missouri River

Abstract

AbstractLittle is known about the habitats of young pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorynchus. Therefore, we compared the distribution and abundance of age‐0 fish of these species collected in benthic trawls among most of the mesoscale habitats comprising the channelized lower Missouri River (i.e., rock‐dike channel modifying structures, large‐channel sandbar, bankline, tributary, floodplain, and wooded island) from 2007 through 2009. Most age‐0 sturgeon were less than 110 mm (fork length) by the end of the growing season. Age‐0 fish were most frequently collected in areas with a relatively fast bottom velocity (0.5–0.7 m/s) associated with channel sandbars, rootless‐dikes, and wing‐dikes and were rarely found at L‐dikes, along banklines, or in tributaries where bottom velocity was slower (≤0.2 m/s). Age‐0 sturgeon habitat use in the lower Missouri River supports the hypothesis that main‐channel areas are important habitats throughout the life cycle of some fluvial specialist species. In light of existing literature on habitat use by wild age‐0 sturgeon, our results highlight their complex ecology in contemporary large rivers throughout their range. Therefore, we do not predict the response of pallid sturgeon to contemporary habitat restoration goals but discuss current knowledge gaps important to characterizing the early life history of Scaphirhynchus spp. Habitat restoration design on the Missouri River should consider the impact on ecosystem structure and the response by early life stages of these species.