NOAA Fisheries release, July 2021 – Oceanic measurements collected during a scientific cruise on NOAA ship Ronald H. Brown recently confirmed that a large area of poorly oxygenated water (known as hypoxia) is growing off the coast of Washington and Oregon. Oxygen-depleted bottom waters occur seasonally along the continental shelf of Washington and Oregon when strong winds blowing along the coast in spring and summer trigger upwellings that bring deep, cold, nutrient-rich water to the surface. These waters fuel blooms of plankton. The plankton in turn feeds small animals like krill which themselves serve as food for many fish. When these blooms die off, they sink to the bottom, where their decomposition consumes oxygen, leaving less for organisms, such as crabs and bottom-dwelling fish. Measurements collected by commercial fishermen using dissolved oxygen sensors provided by NOAA’s Coastal Hypoxia Research Program, as well as data from local moorings, also show a large area of hypoxic water. Earliest Onset in 35 Years – “Low dissolved oxygen levels have become the norm in the Pacific Northeast, but this event started much earlier than we’ve seen in our records,” said Oregon State University Professor Francis Chan, director of the NOAA cooperative institute CIMERS. “This is the earliest start to the upwelling season in 35 years.” Returning to port from the NOAA-sponsored West Coast Ocean Acidification Cruise, Richard Feely, an oceanographer with NOAA’s Pacific Marine Environmental Laboratory, said that dissolved oxygen and ocean acidity measurements are consistent with an event that has the potential to create “dead zones” later this summer. Dead zones occur when dissolved oxygen levels drop so low that crabs and other bottom-dwelling fish perish. The last time scientists observed winds this strong was in 2006 when a large dead zone wiped out crabs and other bottom-dwelling marine life along the continental shelf, Chan said. Concerns about this summer first arose in March, when a NOAA wind measurement station observed an early shift in winds that initiate upwelling. Winds strengthened in April when the first measurements of hypoxic conditions were recorded. In late May, a NOAA Fisheries survey off Washington and Oregon found large phytoplankton blooms and hypoxic conditions on the continental shelf in the area of Grays Harbor, Washington. At about the same time, beachgoers reported large numbers of dead crabs washing ashore in the area of Ocean Shores, Washington. In early June and again in July, samples along the Newport Line, a long-term monitoring transect off Newport, Oregon, also showed hypoxic waters.
