Ocean Indicators for Pacific Ocean Salmon Unsettled for 2024

Image: NOAA Fisheries.

Biologists with NOAA’s Northwest Fisheries Science Center say ocean indicators off the central Oregon coast are decidedly mixed for the coming year, as El Nino develops at the equator, with positive and negative indicators in local waters for emerging salmon.

Ocean indicators for juvenile salmon survival that were posted online in early January reflect a rapidly changing ocean that’s tough to predict, they said.

As of Jan. 11, researchers said the overall message was that the system is unsettled, so at that point all they could do was 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 chance 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, particularly how the changes are likely to affect the salmon experiencing those conditions.

The team tracks 16 key ocean indicators, including seawater temperature and salinity and the number and types of copepods, tiny crustaceans that reflect the food quality 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 will 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, so they can often connect that with how salmon fare, but currently the picture is not clear.

This past year ranked eleventh out of 26 years on record for conditions benefiting salmon, leaving the picture murky, biologists said. The Pacific Decadal Oscillation, a climate pattern affecting the Pacific, 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 usual.

Warm sea surface temperatures along the equator reflected emergence of an El Nino climate pattern earlier this year, but as of mid-January, effects that often include increased storms and precipitation in California and warmer temperatures in the Pacific Northwest had yet to appear along the West Coast.

That in itself is not unusual, as El Nino effects often arrive on the West Coast in winter and spring of the following year, which in this case would be the spring of 2024, they said.