Drones, hydraulics, and climate change: Inferring barriers to steelhead spawning migrations

Abstract

Global climate models suggest dramatic changes in the timing and form of future precipitation in the Pacific Northwest, United States. By some estimates, in the Columbia River drainage, basin‐wide snow‐water equivalencies could decrease by more than 50% before the end of the century, with locally more extreme variation. In the South Fork Clearwater River, Idaho, where hydraulic barriers are currently thought to partially limit ESA‐listed steelhead migrations, changes in precipitation that could exacerbate the intensity and timing of hydraulic barriers presents an obvious conservation concern. Evidence indicates that the strongest steelhead swimmers are capable of sustaining burst speeds for up to 20 s, with maximum speed being a function of fish size (length). Understanding hydraulic dynamics that have implications for migrating fish requires integration of high‐resolution hydraulic models with sufficient resolution to characterize the hydraulic experience of the fish. Unmanned aerial vehicles (drones) have recently emerged as useful platforms for measuring river ecosystems with high precision. Results from habitat surveys and hydraulic modeling can identify locations where intense hydraulic energy may preclude fish passage during critical migration periods. The current as well as future range of discharges can be evaluated with a spatially explicit hydraulic model to quantify when, where, and how long barriers to migration exist. Further, this approach provides a powerful tool for manipulating the digital physical channel form and presents a heuristic opportunity to test hydraulic scenarios to improve migration success. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems Water and Life > Methods

Finding navigation cues near fishways

“…In addition to fixed cameras, use of drones represents an interesting recent addition. Aerial drones have been used in mapping the migration of naked carp ( Gymnocypris przewalskii ) (Zhang et al ., 2022) and to map flow velocities around fishways or migration barriers (Timm et al ., 2019; Strelnikova et al ., 2020). Underwater drones have been used to assess fish communities along depth gradients (Guedes & Araújo, 2022).…”

Determination of River Hydromorphological Features in Low-Land Rivers from Aerial Imagery and Direct Measurements Using Machine Learning Algorithms

“…The mentioned flow distortions under the influence of boulders create unique microhabitats that are essential for the maintenance of biodiversity, since the different hydraulic patterns and pulsations are found and can change in spatial and temporal scales depending on the discharge situation [37]. Moreover, natural obstacles play an important role in the spawning migratory patterns and detailed monitoring of them by applying drones could expand not only the understanding of how to manage the barriers [38], but also how to involve those data for hydromorphological assessment.…”