Summary of ocean ecosystem indicators used to characterize juvenile marine salmon survival in the Northern California Current.
While 2018 was fairly neutral, our 2019 indicators ranked on the warmer side. We found this true especially for the basin-scale indices (PDO, ONI), the local temperature metrics, and the winter ichthyoplankton metrics.
Many of the biological variables were neutral. However, the May-Sept northern copepod anomalies were much higher than normal, ranking second highest in our time series.
The high abundance of northern copepods is usually an indicator of good feeding conditions in the Northern California Current. However, most of 2019’s other indicators point to a more neutral and/or poor year for outmigrating juvenile salmon.
The PDO turned positive (warm phase) in January 2014 and has remained positive through September of 2019. The PDO value in October 2019 was -0.45, was the first negative value since 2013, but then returned to positive (0.15) in November of 2019. Weak El Niño conditions (positive Ocean Niño Index values greater than or equal to -0.5) persisted during the fall/winter of 2018/2019 from October through April and then became neutral throughout 2019.
The winter downwelling period was close to the climatological mean. The onset of upwelling occurred on April 19, 2019, and was relatively strong at the beginning of the season but decreased mid-June and remained weaker than normal. Weak upwelling favorable winds continued through November, which is rare but also occurred in 2013.
Positive temperature anomalies occurred during the winter from mid-October through May punctuated by brief periods of negative anomalies during the beginning of March and May (Figure 1). After the onset of upwelling in mid-April, SST anomalies remained positive until June when negative sea surface temperature anomalies persisted. However, SST anomalies became strongly positive (+2.5°C) from July through at least October.
Hypoxic oxygen concentrations below 1.4 ml/L were observed on the shelf off Newport, OR only in August of 2019 (Figure 2). However, we found hypoxic conditions further north from Grays Harbor, WA to Cape Meares, OR during late June, and the area of hypoxia was 6th out of the 13 years, so about average (Figures 3 & 4).
During the anomalously warm years in 2015 and 2016, the copepod community remained in a warm state and never transitioned to a cold water (upwelling) community during those years. During January through May of 2017, the copepod community was still anomalously warm. However, the community did shift to a cold water community in late June 2017, 2 months later than the 1998–2014 climatology. In both 2018 and 2019, the community shift from winter to summer occurred about one month later than the climatology. However, in 2019, the fall transition (the shift from an upwelling to a downwelling copepod community) was very early, which, together with the late start, resulted in a 2.5-month shorter duration of the cold-water copepod community. During the summer of 2019, the northern copepod anomalies were much higher than normal, ranking second highest in our time series (Figure 5).
Colonial tunicates called pyrosomes were a common occurrence in our plankton nets from fall 2016 through midsummer 2018. We did not encounter pyrosomes in 2019.
The winter biomass of larval stages of fish species common in salmon diets in 2019 was the 20th lowest in the 22-year time series (Figure 6). The community composition of ichthyoplankton in 2019 was dominated by offshore taxa, similar to that seen in 2015-2017, with the community indicator suggesting poor food conditions for piscivorous juvenile salmon that out-migrate into the ocean in 2019.
Ocean Ecosystem Indicators of Pacific Salmon Marine Survival in the Northern California Current
Cape Shirreff field camp on Livingston Island, one of the most breathtaking places in Antarctica. Credit: NOAA Fisheries
North Pacific right whale. Credit: Brenda K. Rone
An oceanic whitetip shark swims near the surface of the water. Photo courtesy of John Carlson.
