Willamette River decadal assessment fish dataset

Natural habitats and communities may change for a variety of reasons but understanding if a change has occurred and its extent requires knowing the original state. The Willamette River Decadal Assessment is an extensive survey primarily of the middle and upper portions of the Willamette River, Oregon, serving as a measurement of baseline conditions for future decades. This Willamette Decadal Assessment fish dataset consists of tabular data from freshwater fish surveys over multiple years in 2 decades, 2011-2013 and 2021-2023. Each decade contains sampling locations within the Willamette River between the mouth (confluence with Columbia River) and the upstream confluence with the McKenzie River. Sampling sites used the SLICES framework for dividing the Willamette River into approximately 1 kilometer river sections of either the mainstem river or off-channel slough areas. Thirteen sentinel slices were included in the survey each year, although sampling some slices was not permitted in certain years due to high water temperatures. Additional sampling sites were randomly selected from the remaining slices. Sampling included boat electroshocking passes and backpack electrofishing samples. Captured native and nonnative individuals were identified to species, except for lamprey. Fish observed but not captured or measured are identified by a separate code. Tabular data include information such as GPS coordinates, fish length, weight, mortality, and species.<br>These data were collected as part of the Willamette Decadal Assessment project. The goal of this assessment is to understand fish community species composition within the Willamette River and how it might change over time, including any potential distribution shifts or changes in species richness. This dataset spans 2 decades, allowing for comparisons between decades as well as serving as a baseline for future freshwater fish surveys in the river.<br>For more information about the SLICES framework, please see Hulse et al. (2002) and the associated website: https://hub.oregonexplorer.info (search for “Willamette Basin SLICES”). For more information about this study and these data, see Penaluna et al. (in review).