ABSTRACT Agricultural development is a global wide‐spread alteration to natural landscapes that can impact stream fish assemblages at multiple scales. Knowing how environmental variables affect stream fish diversity and abundance is important for the conservation and management of stream fish assemblages. Our objectives were to assess fish assemblages associated with environmental variables at landscape and local scales within wadable tributaries of the Missouri River basin in Iowa, USA, a region significantly altered by agriculture. We collected fishes using backpack electrofishing and seine netting and measured instream and landscape variables at 81 sites during May–September, 2022 and 2023. We collected 85,318 fishes of 57 species, with 78% of our total catch composed of just six tolerant species. Stream fish diversity was positively associated with wetland in the riparian buffer, stream depth, stream order and coarse substrate and negatively associated with percent bare bank, stream flow and woody material. Stream fish abundance was regulated by a variety of mechanisms including stream order, coarse substrate, percent bare bank, average stream width, average stream depth, silt substrate, prairie in the riparian landscape and turbidity. Our study contributes new insights into associations among stream fish assemblages and environmental variables in highly impacted agricultural systems and will help managers make decisions regarding the subsequent conservation and management of native fishes.
Lagacy et al. (Fri,) studied this question.