DRIFteRS: A dataset of drift invertebrate densities in streams and rivers across western North America, 1997–2024

Prey availability is among the most influential and highly variable determinants of fish growth and freshwater habitat carrying capacity, yet it remains understudied compared to physical habitat variables (Rosenfeld et al. 2014; Weber et al. 2017; Ouellet et al. 2025). We often lack a clear understanding of how much food is available to fishes, how it varies spatially and temporally, and how it influences responses to restoration (Wipfli et al. 2010; Ouellet et al. 2025; Rossi et al. 2024). Drift invertebrates—the primary food source for juvenile salmonids and other drift-foraging fishes—play a pivotal role in these dynamics.

To better understand the spatial and temporal variability of drift invertebrate abundance and biomass across the freshwater range of drift-feeding salmonids in western North America, we compiled the DRIFteRS dataset (DRift Invertebrates For salmonids in River Systems). The dataset encompasses 6,159 samples of drift invertebrates, and, for a subset of drift samples, associated benthic invertebrate density data, collected from 1,360 reaches on 459 unique rivers and streams spanning 55 river basins considered hydrologically independent (i.e., not nested within the same larger watershed) across British Columbia, Canada, and the U.S. states of Alaska, Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. Sample sites represent a diverse array of river and stream habitats (e.g., headwater, mainstem, side channel), in watersheds with diverse land uses (e.g., urban, wilderness, agricultural), and disturbance histories (e.g., fire, restoration). Collected between 1997 and 2024, the data span the full calendar year and capture daily and seasonal patterns in drift abundance and biomass densities.

When paired with water quality and quantity data as well as remotely sensed environmental landscape data, such as land use / land cover, climate, and disturbance history, channel morphology, and riparian vegetation composition, the DRIFteRS dataset can aid in identifying key drivers of drift invertebrate densities and mean body size and support predictive modeling in unsampled locations and times. The dataset may also be used to analyze aquatic-terrestrial resource flows, derive prey-encounter rates and profitability (mean prey size), and inform broader investigations of sit-and-wait foraging ecology, especially when paired with data on drift-foraging predators. For salmonid-focused applications, the dataset can be integrated into habitat evaluation models, including bioenergetic (e.g., Naman et al. 2019) and life cycle models (e.g., Beechie et al. 2023), to improve estimates of habitat capacity and population dynamics for river- and stream-rearing salmonids. Understanding prey availability dynamics is increasingly important, because rising water temperatures increase salmonid metabolic demands (Crozier et al. 2010). Flow regime transitions (i.e., snow or glacier dominated to rain dominated; Beechie et al. 2013), wildfire frequency and intensity (Hessburg et al. 2021), as well as plant community and phenology shifts (Cleland et al. 2007; Franklin et al. 2016) are all predicted to change with rising temperatures and are potential drivers of terrestrial and aquatic invertebrate prey quality and availability in lotic systems. These insights can ultimately inform restoration prioritization and design, helping managers consider food resource implications when evaluating restoration priorities and match habitat improvement to food supply.

Beechie, T. J., H. Imaki, J. Greene, A. Wade, H. Wu, G. Pess, P. Roni, J. Kimball, J. Stanford, P. Kiffney, and N. Mantua. 2013. Restoring salmon habitat for a changing climate. River Research and Applications, 29:929–960.

Cleland, E. E., I. Chuine, A. Menzel, H. A. Mooney, and M. D. Schwartz. 2007. Shifting plant phenology in response to global change. Trends in Ecology and Evolution, 22:357–365.

Crozier, L. G., R. W. Zabel, E. E. Hockersmith, and S. Achord. 2010. Interacting effects of density and temperature on body size in multiple populations of Chinook salmon. Journal of Animal Ecology, 79:653–662.

Franklin, J., J. M. Serra-Diaz, A. D. Syphard, and H. M. Regan. 2016. Global change and terrestrial plant community dynamics, Proceedings of the National Academy of Sciences, 113:3725–3734.

Hessburg, P. F., S. J. Prichard, R. K. Hagmann, N. A. Povak, and F. K. Lake. 2021. Wildfire and climate change adaptation of western North American forests: a case for intentional management. Ecological Applications, e02432,

Naman, S. M., J. S. Rosenfeld, J. R. Neuswanger, E. C. Enders, and B. C. Eaton. 2019. Comparing correlative and bioenergetics‐based habitat suitability models for drift‐feeding fishes. Freshwater Biology, 64:1613–1626.

Ouellet, V., A. H. Fullerton, M. Kaylor, S. Naman, R. Bellmore, J. Rosenfeld, G. Rossi, S. White, S. Rhoades, D. A. Beauchamp, M. Liermann, P. Kiffney, and B. Sanderson. 2025. Food for fish: Challenges and opportunities for quantifying foodscapes in river networks. WIREs Water, e1752.

Rosenfeld, J. S., N. Bouwes, C. E. Wall, and S. M. Naman. 2014. Successes, failures, and opportunities in the practical application of drift-foraging models. Environmental Biology of Fishes, 97:551–574.

Rossi, G. J., J. R. Bellmore, J. B. Armstrong, C. Jeffres, S. M. Naman, S. M. Carlson, T. E. Grantham, M. J. Kaylor, S. White, J. Katz, and M. E. Power. 2024. Foodscapes for salmon and other mobile consumers in river networks. BioScience, biae064.

Weber, N., N. Bouwes, and C. Jordan. 2017. Accounting for spatial and temporal variation in macroinvertebrate community abundances when measuring the food supply of stream salmonids. Freshwater Science, 36:364–376.

Wipfli, M. S., and C. V. Baxter. 2010. Linking ecosystems, food webs, and fish production: Subsidies in salmonid watersheds. Fisheries, 35:373–387.