Conflicting Ocean Indicators Suggest Moderate Returns of Pacific Salmon

Juvenile salmon encountered a mixed bag of ocean conditions off the West Coast in 2025, based on an annual analysis by NOAA Fisheries and Oregon State University researchers.

The researchers examine 16 ocean indicators, from temperature and salinity to the quantity and quality of food available to juvenile salmon during their first months in the ocean. That is a crucial period for young fish as they search for prey to grow big and fast enough to stay ahead of predators.

Researchers refined the indicators through years of monitoring. They help fish managers anticipate how many juvenile salmon will survive to grow large enough to be caught in fisheries or return to rivers as adults in the next few years. The insight can help shape fisheries worth millions of dollars to the coastal economy and ensure that recreational, commercial, and tribal fisheries continue at sustainable levels.

Salmon Encounter Mixed Conditions

Warmer conditions leading into last winter signaled that young salmon entering the ocean in the spring would find prey less abundant. That prey would also largely be made up of fish species that normally correlate with low juvenile salmon survival. The annual upwelling of cold, deep-ocean water along the West Coast started strong in the spring, which is typically a positive sign for salmon. Juvenile coho salmon sampling in June showed the greatest abundance of all the years sampled. However, the upwelling faltered in July, leading to an overall mix of good to moderate ocean conditions for the local physical and biological indicators for the year.

Researchers noted poor food indicators in the winter and a cool start to the summer, followed by weakened winds in late summer. These contrasting effects suggest a moderate outlook for salmon, the researchers found. The combination of indicators for 2025 ranked roughly midway between the years with the best outlook for salmon and those with the worst. In the past, such conditions have typically led to modest marine survival and returns of adult salmon.

"The start to the upwelling season in 2025 looked favorable for a highly productive year to come," said Jennifer Fisher, a research fisheries biologist at the Northwest Fisheries Science Center's Newport Research Station. "However, the upwelling winds weakened mid-summer, crustaceans (like krill) were scarce, and jellies were abundant. These are all signs of low productivity and poor habitat for many species, including juvenile salmon."

The ocean indicators based on data collected off the Oregon Coast are most relevant to Northwest salmon stocks. Since the ocean changes gradually, however, the indicators also provide some insight into conditions likely to affect salmon across the broader West Coast, said Brian Burke, a research scientist at the Science Center.

Years of Monitoring Tracks Indicators

The Newport Research Station's team regularly monitors ocean conditions along the Newport Hydrographic Line : one of the best records of ocean change on the West Coast. Scientists survey the line twice each month, as they have done for the past for 28 years, weather permitting. The data they collect reveals patterns and can lead to new insights into how the ocean changes-and how the changes are likely to affect the juvenile salmon.

The team tracks 16 key ocean indicators, including:

• Seawater temperature
• Salinity
• Potential fish prey for outmigrating juvenile salmon
• Number and types of copepods (tiny crustaceans that reflect the habitat quality for juvenile salmon when they first enter the ocean)
• Catches of juvenile coho salmon and Chinook salmon

"These indicators track the ecosystem health, so we can often connect that with salmon survival when they are the most vulnerable, when they first enter the ocean habitat" Fisher said. "Right now, the signals are mixed, reminding us how important it is to continually track ocean conditions and try to understand the mechanistic linkages between ocean conditions and juvenile salmon survival."