2025 Summary of Ocean Ecosystem Indicators

Ocean ecosystem indicators suggested moderate conditions for juvenile salmon in 2025, with the overall rank being #11 out of 28, with a rank of 1 being the best for juvenile salmon. This rank was favorably skewed by the #1 and #7 rank of the summer and winter Pacific Decadal Oscillation (PDO) respectively. However, this basin scale index has recently shown weaker correlations with regional and local sea surface temperatures and ecosystem processes, compared to historical patterns. After removing these PDO ranks, the adjusted overall rank shifted to #12 out of 28- still indicating moderate conditions.

Weak La Niña conditions persisted throughout 2025. More locally, strong winter downwelling was punctuated by weak but persistent upwelling favorable winds throughout January that resulted in cooler coastal sea surface temperatures from mid-January through February. Despite this, the biomass of winter (January-March) ichthyoplankton—that become important forage for juvenile salmon—was much lower than average and the species composition of these prey had higher proportions of offshore larval fish species, such as rockfish. Together, these results suggest poor quantity and quality of juvenile fish prey available for piscivorous juvenile salmon that entered the ocean in the spring of 2025.

Come spring, the physical spring transition—marking the beginning of the upwelling season—occurred on April 10, aligning with the long term mean. Upwelling favorable winds were stronger than average until mid-July. Upwelling winds weakened from July through September 27, when the fall transition occurred. Despite the stronger than average beginning to the upwelling season, near bottom temperatures on the continental shelf oscillated between weakly above and below average, and cool (8°C) upwelling water was not observed on the shelf until May 14, over a month past the physical spring transition. Gelatinous taxa were also more prevalent in nets and washing ashore in the summer—a sign of a less productive ocean. These variable conditions led to average ranks for the temperature indices in the Stoplight chart.

The copepod community transitioned from a winter to a summer community on April 29, also aligning with the long term mean. Biomass anomalies of the lipid-rich, northern copepod species remained above average from January to September while the biomass anomalies of the southern copepods were below average. This resulted in ranks of #18 and #7 out of 28 for the northerns and southerns respectively.

The juvenile salmon indicators also reflect mixed conditions, as Chinook salmon catches ranked slightly higher than average, contrasting sharply with coho salmon catches, which continued on an upward trajectory and ranked the highest in the time series.

Overall, most of the local physical and biological ecosystem indicators were average for 2025. The notable departures were the lower than average ranks for the two winter ichthyoplankton indices of juvenile salmon prey. Together, these patterns indicate moderate to poor ecosystem conditions for juvenile salmon outmigrating to the ocean during the spring of 2025.

Pacific Decadal Oscillation and Ocean Niño Index

The PDO turned negative (cool phase) in January 2020 and has remained strongly negative through 2025. The most negative PDO values of the 28-year time series occurred during the summer of 2025, ranking the summer PDO #1. Historically, the PDO index has been well correlated with marine ecosystem changes in the North Pacific. However, recent reanalysis suggests that pan-Pacific warming has been the leading mode in the North Pacific since 2014, and the PDO is no longer correlated with local patterns. Therefore, the #1 ranking of the coldest PDO in our time series should be interpreted with caution.

The Ocean Niño Index (ONI) turned weakly negative in August 2024 following the 2023/24 El Niño event that persisted for 12 consecutive months. Equatorial SSTs have continued to remain weakly negative through 2025 The National Weather Service Climate Prediction Center predicts that La Niña conditions will persist through 2025, transitioning to ENSO neutral conditions in January-March 2026.

Upwelling Index at 45°N

Strong winter storms led to stronger-than-average downwelling during the winter of 2025-26. Even still, upwelling-favorable winds were weak but persistent throughout January leading to colder than average sea surface temperatures across the region from mid-January to mid-February. The physical spring transition, marking the persistent upwelling season, occurred on April 10. Following the transition, upwelling-favorable winds were stronger-than-average until mid-July. Despite these strong upwelling favorable winds at the beginning of the season, cold (8°C), upwelled water was not observed near bottom on the shelf at station NH-5 until May 14 (hydrographic spring transition). From mid-July to the fall transition that occurred on September 27, upwelling winds were fairly weak. Overall, the length of the upwelling season was close to the 28-year average, but the strong early upwelling resulted in total upwelling being above average for the entire season.

Sea Surface Temperatures from NOAA Buoys

Winter 2024-25 began warmer-than-average (<1°C) and quickly transitioned to negative anomalies in mid-January through most of February following weak upwelling favorable winds. Even though the physical spring transition occurred on April 10, SST anomalies fluctuated between positive and negative from March through May, with a sharp positive increase at the end of May (~ 2°C). SSTs throughout the summer, from June-July were cooler than normal and marked the coldest period of the year with anomalies frequently dropping below -2°C. Conditions reversed in August, with mostly positive SST anomalies through mid-November following weak upwelling favorable winds and pulses of downwelling favorable winds.

Water Temperatures on the Shelf and Slope

Along the Newport Hydrographic Line, monthly anomalies of near-bottom (50-m) water temperature at the shelf station (bottom panel) fluctuated between weakly negative and positive for most of the year with a sharp transition to warmer than average temperatures from August through October. At the continental slope (top panel) station, temperatures at 150-m were the coldest they have been since 2014 throughout most of the year until shifting to warmer than average in September and October.

Hypoxia

Strong, persistent hypoxic conditions (oxygen concentrations below 1.4 ml L^-1) have become common on the shelf (50-m depth) since 2017. In 2023, hypoxic conditions were not observed during any sampling date. In 2025, hypoxic conditions were observed during four of the six sampling dates in June, July, and August.

Zooplankton

In 2025, the transition from the winter copepod community to the summer community occurred on April 29, which is right on par with the long term average of May 3. The timing of this transition is biologically important because it marks the transition from a warm water, lipid-deplete, southern copepod dominated community to a cold water, lipid-rich, northern copepod dominated community. This transition is called the “biological spring transition”, and the timing of this transition has been linked to favorable feeding conditions for salmon.

At station NH-5, on the shelf, northern copepod biomass has been higher-than-average since 2020. One exception to this was negative anomalies during the winter-spring of 2024. Since then, northern copepod biomass has been above average from the summer of 2024 through the summer of 2025. From July-October, the biomass anomalies were neutral, possibly in response to the weaker upwelling winds. Overall, northern copepod biomass ranked 18^th in the time series.

Since 2020, the southern copepod biomass has changed more frequently compared to the northern copepod biomass, oscillating from higher than average in the winters and lower than average during the summers. In 2025, southern copepod biomass was consistently lower-than-average from January to September, ranking 7th in the time series. During the same period, species richness was also lower than average, ranking 7th in the time series. The lower than average southern biomass and modest northern biomass suggests a moderate prey base.

Winter Ichthyoplankton

The biomass of coastal ichthyoplankton and species composition of coastal and offshore larval fish in winter (January-March) are strong indicators of the quantity and type of juvenile fish prey that will be available for migrating juvenile salmon that enter the ocean in the spring. The winter indices of the coastal ichthyoplankton prey biomass and the ichthyoplankton community composition are typically both positive during colder ocean conditions and negative during warmer ocean conditions. This results in higher than average biomass of coastal taxa such as larval Pacific sand lance, smelts, and sculpins during cool ocean conditions, and lower biomass of these taxa during warm ocean conditions, with a shift to more offshore taxa such as larval rockfish, northern anchovies, and Pacific sardines.

The winter index of coastal ichthyoplankton prey biomass in 2025 was ranked the 24^th, lowest value in the 28-year time series, suggesting low biomass of food for outmigrating juvenile salmon in the spring. The winter ichthyoplankton community composition in 2025 had modest proportions of coastal larval fish species, such as larval smelt, but high proportions of offshore fish species, such as larval rockfish, resulting in the community composition value ranking the 21^st lowest in the 28-year time series. Together, these results suggest poor quantity and quality of prey available for piscivorous juvenile salmon that entered the ocean in the spring of 2025.

Salmon

The abundance of juvenile salmon observed in our June Juvenile Salmon and Ocean Ecosystem Surveys (JSOES) has a significant and positive relationship with adult salmon returns. Specifically, the abundance of yearling Chinook salmon in our survey correlates positively with spring Chinook jack counts at Bonneville Dam the following spring and to adult spring Chinook counts at Bonneville Dam two years later. Similarly, the abundance of yearling coho salmon during June surveys also has a significant and positive relationship to coho smolt to adult survival. Thus, catches of yearling salmon in June may be a good indicator of first year ocean survival of yearling Chinook and coho salmon and can inform year class strength. In our June 2025 survey, yearling Chinook salmon catches ranked 11th and coho salmon ranked 1st in the time series. Coho salmon catches have ranked high in the time series for the last three years. Chum salmon catches (not shown in the stoplight) have also ranked high in recent years. This suggests that Chinook salmon jack counts at Bonneville Dam in spring 2026 and adult returns of spring Chinook salmon at Bonneville in 2027 will be about average, and coho salmon returns in 2026 should be above average for the survey years of 1998–2025.

Pyrosomes and other gelatinous zooplankton

Pyrosomes were present in small numbers during our May and September Northern California Current Broadscale Ecosystem surveys. These surveys sample from northern California to northern Washington and go further offshore (65 nmi) than our regular monthly sampling along the Newport Hydrographic Line (25 nmi). The pyrosomes collected during these surveys were generally found further than 35 nmi offshore of Newport and to the south. Pyrosome size consisted primarily of individuals less than 5 cm in length.

In the summer and fall, Pacific sea nettles washed up in large numbers on Oregon beaches, and large swarms were also noted nearshore. Large abundances of other gelatinous taxa, like the Common Salp, were also observed in the fall.