7 Ways El Niño and Large Marine Heatwave Could Affect West Coast Marine Species

By fisheries.noaa.gov, fisheries.noaa.gov.

A large marine heatwave has bathed parts of the West Coast in very warm ocean waters over the past year, breaking temperature records in the Pacific. NOAA has also announced that El Niño has developed in the tropical Pacific and is predicted to intensify to a moderate or strong level this fall. El Niño represents another form of marine warming, though with different drivers and influences. The prolonged period of high temperatures could affect fisheries and marine life in the California Current that have already been buffeted by shifting ocean conditions over the last decade.

One factor may help dampen the impacts, though: The same strong upwelling of cool water along the coast that fuels the West Coast ecosystem with nutrients could help keep some warmer waters at bay, as happened in 2025.

We have seen these back-to-back heat events before. About a decade ago, a major marine heatwave known as “The Blob” began raising ocean temperatures off the West Coast, peaking in 2015. One of the strongest El Niños on record followed in 2015–2016, amplifying ocean warmth—as the current forecast predicts for the coming year. That was a worst-case scenario that drove changes around the world. The Pacific endured a record count of tropical cyclones and the Caribbean Sea and parts of Africa experienced severe droughts. That situation was more extreme than now, with the Blob lasting longer and affecting the entire West Coast compared to the smaller recent marine heatwave. However, research and observations during that unprecedented climatic pileup suggest the kind of changes we may see in the coming months along the West Coast. Though these changes are centered in the Pacific, they have far-reaching impacts.

Here are some of the ways warming water can impact marine life, coastal communities, and economies.

Originally published on 12 June, 2026.

Vessels from the West Coast squid fleet followed market squid north into Oregon as ocean waters warmed, leading Oregon to adopt its first regulations for squid fishing in the state. Photo courtesy of California Department of Fish and Wildlife.