Warming Ocean Highlights Need to Improve River Habitat, Estuary for Salmon

At its March meeting, the Council heard the latest research on the impact of ocean conditions on Chinook and coho returns to the Columbia River.

The overarching message, according to Brian Burke, supervisory research fish biologist with the National Oceanic and Atmospheric Administration, is that while we’re experiencing a temporary uptick in salmon numbers for now, in the long term, conditions will trend back down, highlighting the need for more information to make good decisions on where to focus recovery efforts.

As the climate warms, marine heatwaves become more frequent, changing the ocean’s water temperature patterns. The normally cold waters along the West Coast that are so beneficial to salmon heat up, and it’s expected to get worse, said Burke. For now, however, conditions last year were relatively good, setting the stage for a healthy number of salmon in 2021. “We saw widespread and significant improvement in recent ocean conditions,” noted Burke. “But it’s not the beginning of an upward trend; it’s a temporary respite from a long-term decline.” Life cycle models predict that the changes from climate change will contribute to a rapid decline in populations.

Despite this sobering outlook, Burke said there are things we can do to improve river and estuary habitat to increase the viability of salmon in other life stages; improving river conditions can influence their survival in the ocean. Efforts to better understand and address predation is also a critical piece of the puzzle.

According to a NOAA study, “Larger and stronger fish better survive the ocean, so habitat restoration that improves growth can improve their odds…we need to understand the role of competitors, predators, and prey in marine salmon survival and whether management options could help improve salmon prospects. There may also be linkages between estuary restoration and initial growth rates in the ocean that could improve survival.”

The Council’s Fish and Wildlife Program recognizes the ocean environment as an integral component of the Columbia River ecosystem, and its measures support monitoring ocean conditions and in-river restoration actions to determine those with the greatest benefit.

“Now is the time to ramp up marine science efforts to identify and inform additional management actions,” said Burke.

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