Ocean Indicators for Pacific Ocean Salmon Unsettled for 2024

Image: National Oceanic and Atmospheric Administration.

Biologists with NOAA’s Northwest Fisheries Science Center have said that ocean indicators off of the central Oregon coast are decidedly mixed for emerging salmon in local waters in the coming year, as El Niño develops at the equator.

Indicators for juvenile salmon survival, which were posted online in early January, reflect a rapidly changing ocean that is tough to predict they said.

As of Jan. 11, researchers said the overall message was that the system is unsettled, leaving them to watch and wait.

The team from the research station regularly monitors ocean conditions along the Newport Hydrographic Line, one of the best records of ocean change on the West Coast. Scientists have surveyed the line twice monthly, weather permitting, for 26 years.

The information collected reveals patterns and insights into how the ocean changes, and particularly how those shifts are likely to affect salmon in those conditions.

The team tracks 16 key ocean indicators, including seawater temperature, salinity and the number and types of copepods, tiny crustaceans that reflect the food quality available for juvenile salmon when they first enter the ocean.

Decades of monitoring have demonstrated that these ocean indicators correlate with juvenile salmon growth and survival – and how many adults are expected to return to rivers to spawn.

According to Jennifer Fisher, a research fisheries biologist at the science center’s Newport Research Station, these are factors that influence the health and survival of salmon, but currently, the picture is not so clear, she said. 

This past year ranked 11th out of the 26 years on record for conditions benefiting salmon, leaving the picture murky, biologists said.

The Pacific Decadal Oscillation, a climate pattern affecting the Pacific Ocean, indicated conditions that often benefit salmon, while local and regional temperatures affecting salmon varied over the summer, indicating more contradictory conditions.

Researchers observed that copepods were cooler water species rich in fats that help fuel the growth of young salmon. Still, the abundance of these high-fat crustaceans was lower than in some years. Survey catches of juvenile salmon showed slightly fewer yearling Chinook salmon than usual, but more coho salmon than normal.

Warm sea surface temperatures along the equator reflected emergence of an El Niño climate pattern earlier this year. As of late-January, El Niño effects, which often include increased storms and precipitation in California and warmer temperatures in the Pacific Northwest, had begun to appear along the West Coast. 

El Niño often arrives on the West Coast in winter and spring of the following year, which in this case would be the spring of 2024, but the timing can vary.