Plots

Maps of near-bottom ocean properties (dissolved oxygen in µmol kg-1, temperature in degrees C, salinity, and density in kg m-3) during the summer upwelling seasons of 2021-2024. The upwelling season is defined as between the spring and fall transitions when winds are predominantly southward in the upwelling-favorable direction, see Cumulative Wind Stresses for Oregon. The majority of the data are within 10 meters of the sea floor. The blue-cyan transition for dissolved oxygen at 60 µmol kg-1 denotes the hypoxia threshold. The percentage of the continental shelf (water depths < 200 m) that is hypoxic each year is indicated. Bottom depth in m; the 200-m isobath marks the edge of the continental shelf. Plots from Barth and Coleman (2025).

Data were collected, processed and analyzed by Jack Barth and Sean Coleman at Oregon State University.Data are from the World Ocean Database, the National Oceanic and Atmospheric Administration (NOAA), and the International Pacific Halibut Commission. For 2021, additional data were obtained from the Oregon Department of Fish and Wildlife and the Ocean Observatories Initiative as described in Barth et al., (2024). In 2022, we used data from the In Situ Ichthyoplankton Imaging System (ISIIS). NOAA surveys include the West Coast Bottom Trawl Groundfish Survey, the Hake Survey, Juvenile Salmon and Ocean Ecosystem Survey (JSOES), the Northern California Current Survey (NCC), and the Pre-Recruit Survey.

Acknowledgements

We thank the captain and crews of the oceanographic research vessels that made measurements at sea and our many colleagues who conceived of, planned, and executed these programs. These include colleagues at the National Oceanic and Atmospheric Administration (NOAA) and Oregon State University.We acknowledge the Ocean Observatories Initiative, a major facility fully funded by the US National Science Foundation under Cooperative Agreement No. 2244833, for the mooring data. Thanks also to the International Pacific Halibut Commission for data from 2021-2023. Funding for this work was supported by NOAA Grants NA18NOS4780169, NA21OAR4320203, and NA22NOS4780171.