June 18, 2013
Researchers from the PISCO program were at sea last week to service moored ocean sensors deployed off the central Oregon coast. Preliminary data collected by those sensors indicates that dissolved oxygen levels (DO) in the nearshore (in 15-meters depth, or ~49-feet depth) waters of Cape Perpetua has declined rapidly over the past two weeks coincident with the strong upwelling-favorable winds that we have seem recently. The Cape Perpetua sensors recorded DO as low as 1.0 ml per liter in the nearshore. Nearshore (in 15m depth) sensors deployed to the north of Newport off Cape Foulweather recorded DO minima that are slightly above 1.0 ml per liter over the same time period.
The 2013 upwelling season arrived earlier this spring than average. Data from a sensor deployed over the mid-shelf off Cape Perpetua in deeper water (70-meter depth) indicates that oxygen has declined more or less persistently since the onset of the upwelling season. Minimum oxygen (DO) levels have declined to approximately 0.9 ml per liter in this Cape Perpetua region. This signals the formation of low oxygen water over the shelf in the waters south of Newport. Mid-shelf casts taken off Cape Foulweather (north of Newport) did not show any DO values below 1.2 ml per liter and again suggest important spatial patterning in the risk of hypoxia along the central Oregon coast.
Bottom line: The oxygen values that we have recorded are relatively low but have yet to reach the severe hypoxia level (≤0.5 ml per liter) that we have associated with the most acute impacts on marine life in the past. That we are already seeing <1.0 ml per liter DO levels is cause for concern as we are still early half of the upwelling season. We will return for additional surveys and sensor servicing and data download on the OSU R/V Elakha starting on July 10th and will provide updates on how this season’s hypoxia evolves. Contact us for more information or to share your observations. To learn more, check out our Frequently Asked Questions and Hypoxia Resources pages.
August 23, 2012
Recent results from multiple ocean observing platforms indicate that moderate to severe hypoxia is occurring along parts of the central Oregon shelf. The MI_LOCO/PISCO bottom lander at 70m (38 fathom) depth off Cape Perpetua has recorded severe hypoxia (DO < 0.5 ml/l) since August 12th with DO levels dropping as low as ca. 0.1 ml/l. These are among the lowest values that we have measured over the past decade. When upwelling-favorable winds have been strong, this offshore near-bottom hypoxic water has been transported into the inner shelf (water depths less than 50 m = 27 fathoms). A shallow-water (15 m = 8 fathoms) PISCO mooring at Cape Perpetua has recorded similarly low (<0.5 ml/l) oxygen values during the recent period of strong upwelling-favorable winds. As in past years, the most intense hypoxia appears to be centered south of Newport. Glider data from the NH-line off Newport from Aug 3-8 and 18-20 indicate that hypoxic (dissolved oxygen < 1.43 ml/l) though not severely hypoxic (<0.5 ml/l) water extends across the shelf and extends up to 20 m above the bottom. An inner-shelf (15 m = 8 fathoms) PISCO mooring located off Lincoln Beach also shows hypoxia but not severe hypoxia.
Based on the weather forecast, we expect hypoxic conditions to persist or worsen over the next week. Conditions conducive to further hypoxia are likely to persist until strong low pressure systems reverse the regional winds which typically occurs in late September to early October. While we are working to make additional observations, we wanted to share these results with you in a timely manner.
Though there is the potential for this hypoxic event to impact fisheries, there is not enough data yet to know which areas or species will be affected. If you or anyone you know would like to report unusual fish behavior or changes in catch in pots or traps, please contact us. We will be sending out updated information as we collect and analyze more data.
August 19, 2011
PISCO researchers Jack Barth and Francis Chan are reporting low dissolved oxygen (DO) concentrations off the central coast of
ODFW biologists Mike Donnellan and Bill Miller recently surveyed deep (~40-45 m) reefs offshore of Cape Perpetua and Lincoln City with a Remotely Operated Vehicle. From August 8-10, they observed healthy, active fish communities (e.g., black , canary, quillback, and copper rockfishes) at the
Though there is the potential for this hypoxic event to impact fisheries, there is not enough data yet to know which areas or species will be affected. If you or anyone you know would like to report unusual fish behavior or changes in catch in pots or traps, please contact us We will be sending out updated information as we collect and analyze more data.
June 27, 2011
Researchers from the Northwest Fisheries Science Center (at HMSC in Newport, OR) report that they are already seeing fairly low oxygen values in June (1.40 ml/L at NH05 on 22 June at 56 m depth = hypoxic) yet upwelling has been very weak this spring (based on the PFEL upwelling index). Local winds have been weak as well although they were blowing pretty strong on June 24th. There has been a huge bloom the past week or two so maybe it has already begun to sink to the bottom and began to decompose. In addition, copepod biomass is twice as high this spring as any other spring in the past 16 years thus maybe the rain of pellets to the sea floor and subsequent decomposition has drawn the oxygen down to hypoxic levels.
June 24, 2011
Recent observations from PISCO profiles off Cape Perpetua and the NH10 mooring off Newport show dissolved oxygen levels to be hovering around 1.5 ml/L at 36.5 fathoms (73 meters). These values are expected for this time of year and are the result of upwelling caused by persistent winds from the north. For clarity, the shelf is not described as hypoxic until dissolved oxygen levels reach 1.4ml/L.
June 8, 2011
ODFW attempted to conduct their pre-season sampling on 5/31-6/1, but were shut out due to very poor underwater visibility on the seafloor. However, the limited video footage that was obtained at Cape Perpetua was indicative of non-hypoxic conditions (e.g., plentiful, active fish, healthy-looking epibenthic macroinvertebrates). Video review and analysis of ROV footage dating to 2000 is ongoing, with results and a report planned for later this year. An analysis of fisheries performance versus hypoxia is also planned for later this year.
ODFW's acoustic telemetry moorings that were deployed at Cape Perpetua in 2010 to research rockfish movements and home range is complete, and will not be re-deployed in 2011.
For more information please contact us.