June 15, 2026 — 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.

1. Shifting Fisheries

Research found that some commercial West Coast species, such as market squid, may be sensitive to these long-term and episodic changes in ocean temperatures. The shift of market squid north along the West Coast in response to warming from the Blob and subsequent El Niño created new fishing opportunities in Oregon and Washington during the Blob that remained afterward. Squid landings in Oregon rose from none in 2015 to nearly 3 million pounds worth more than $1 million in 2016 and continued to grow rapidly through 2020. This provided new opportunities for purse seine vessels whose opportunities in other fisheries affected by the Blob—such as sardine, Alaska herring, and Alaska salmon—had dwindled. Seafood processors in Oregon scaled up to handle more squid, and Oregon fisheries managers developed their first regulations for the emerging squid fishery. Market squid had been the largest commercial fishery by volume in California, but California landings dropped by more than half from 2014 to 2015. They remain substantially lower than they were prior to the Blob and El Niño.

Meanwhile, tropical species such as whale sharks and hammerhead sharks made northerly appearances off Southern California while fishing vessels caught albacore tuna much closer to shore as far north as Washington. Fishing boats caught a skipjack tuna off the Copper River in Alaska, and surveys turned up an ocean sunfish and thresher shark off southeast Alaska. Pacific bluefin tuna increased in number and size in U.S. waters, exciting recreational anglers and generating new revenue for the charter fleet. This year, Southern California anglers have begun catching dorado and yellowfin tuna much earlier in the year than usual, suggesting these northerly shifts may have begun.

2. Hungry California Sea Lion Pups

Higher sea surface temperatures also affect other fish species, including sardines and anchovy. These fish are high-energy staple foods for California sea lions that breed in Southern California’s Channel Islands, but declined with warming ocean temperatures. Sea lions turned to lower quality forage species such as rockfish and squid. Nursing sea lion mothers had to travel farther to find the food their pups needed, forcing pups to fast for longer periods at the rookery. The weight of sea lion pups declined, according to long-term studies in the Channel Islands . In El Niño years, many hungry pups set off on their own in search of food before their usual weaning time. In 2013–2016, as many as 4,000 pups arrived on California beaches, skinny and hungry. These extreme events taxed rehabilitation facilities and prompted NOAA Fisheries to declare an Unusual Mortality Event for the species. Researchers later estimated that an increase of 1 degree Celsius in sea surface temperatures could reduce the growth rate of the sea lion population to zero. A 2-degree rise would reduce the population size by about 7 percent.

Read the full article at NOAA Fisheries