Ocean Indicators Summary for 2021
Summary of ocean ecosystem indicators used to characterize juvenile marine salmon survival in the Northern California Current.
Summary of Ocean Indicators for 2021
2021 was a very productive year off Newport, Oregon, characterized by an early spring transition, strong upwelling, cold salty, low oxygen water, and high chlorophyll concentrations on the shelf. These conditions resulted in higher than average biomass of cold water northern copepods and lower than average biomass of warm water southern copepods.
Our ocean ecosystem indicators ranked second best in the 24-year time series (2008 ranked first). The indicators on the stoplight chart of ocean conditions are mostly green, signaling productive ocean conditions for juvenile salmon and other marine species. The early onset of upwelling led to cool and productive ocean conditions during the winter and early spring. This winter 'pre-conditioning' was likely the driver of the highest annual biomass of northern copepods observed in the 24-year time series.
Pacific Decadal Oscillation and Ocean Nino Index
The PDO turned negative (cool phase) in January 2020 and remained negative until 2021. The values in October and November ranked the 10th and 11th lowest, respectively, since the time series began in 1900. The Ocean Niño Index (ONI) also signaled cold ocean conditions. The ONI turned negative in May 2020 and has remained negative throughout 2021, with La Niña conditions (values less than or equal to -0.5 °C for five consecutive three-month periods) occurring from August 2020 through May 2021. The National Weather Service Climate Prediction Center states that the ONI is predicted to remain negative throughout the winter and transition to ENSO-neutral conditions in the spring of 2022.
Upwelling Index at 45°N
In the Newport Hydrographic Line region, the onset of upwelling began quite early. Upwelling favorable winds occurred during the winter in mid-February, followed by periods of downwelling/upwelling cycles until the onset of persistent upwelling favorable winds in mid-March. Following the spring transition (onset of upwelling), upwelling winds were weak until May, when strong winds persisted. They were only punctuated by a brief downwelling event in June. Upwelling strength was above the long-term mean from May until September. The fall transition to winter downwelling conditions occurred in mid-September, yet brief periods of weak upwelling favorable winds occurred through October.
Sea Surface Temperatures from NOAA Buoys
Upwelling favorable winds in February 2021 resulted in the transition from positive temperature anomalies from December 2020 through January 2021 to negative sea surface temperature anomalies that persisted through much of the year in 2021. Positive temperature anomalies occurred in June, following the brief downwelling event that month. Strongly negative temperature anomalies followed in July through September until the fall transition in mid-September. Warm temperature anomalies occurred in early October following the fall transition, but weak upwelling favorable winds kept the surface temperatures weakly negative in mid-October.
Newport Line Water Temperatures on the Shelf and Slope
Along the Newport Hydrographic Line, the near-bottom water temperature on the continental shelf (50 m) was cooler and saltier (not shown) than the long-term mean throughout 2021, likely a result of the strong upwelling. Anomalies on the continental slope (150 m) were weakly positive during the winter of 2020/21, and they turned negative in March of 2021 and remained negative throughout the year.
Hypoxic oxygen concentrations below 1.4 ml/L were measured on the shelf (50-m depth) during each sampling event from May through October 2021. Although hypoxic conditions occur during most summers, increased incidence of hypoxic water has occurred since 2017, with 2021 having the longest time period with consistently hypoxic water on the shelf.
Throughout 2021, northern copepods continued an increasing trend that began in 2020 after prolonged negative biomass anomalies from 2015-2017. The biomass anomalies remained strongly positive throughout the year, with the spring-summer anomalies ranking the highest in the 24-year time series. Neocalanus, a large sub-arctic copepod, was also abundant (not shown) in offshore samples along the OR and WA coast during our May survey, signaling cold ocean conditions. This species was also observed in 2008; the year ranked highest for favorable ocean conditions for juvenile salmon.
Southern copepods were below average for much of 2021, continuing a decline since the marine heatwave that occurred from 2014 - 2016. These values suggest above-average feeding conditions for pelagic fishes off central Oregon in 2021.
The transition from a warm-water lipid-deplete winter copepod community to a cold-water summer community occurred on April 16 in 2021. The past two years mark the earliest transition dates since before 2014.
Pyrosomes and other gelatinous zooplankton
While colonial tunicates called pyrosomes were common in our plankton nets from fall 2016 through midsummer 2018, they have been absent over the past couple of years. They maintain a continued presence in California, while their occurrence is spottier in Oregon waters. Large blooms of pyrosomes were washing ashore in Newport during the winter months in 2020. At sea, pyrosomes were encountered offshore of Newport in April. Small pyrosomes were collected in plankton nets off the Oregon/California border and at Heceta Head in May 2021. Pyrosomes have not been spotted on the Newport Line this summer or fall.
Also of note were large offshore abundances of salps in our May survey along the OR and WA coast. Their increased presence was also noted along the Newport Line in the summer months.
In winter (January - March) of 2021, the Index of Coastal Prey Biomass (ICPB; blue bars) was above the long-term mean and the 6th highest biomass in the 24-yr time series, suggesting above-average prey biomass for out-migrating salmon. The community composition of ichthyoplankton (not shown) in 2021 was a mixture of both coastal and offshore taxa. These results suggest above-average biomass (ICPB) and close-to-average (community) prey conditions for piscivorous juvenile salmon that out-migrated in 2021.