07/26/2026 by David McGuire
With the imminent “super” El Niño in 2026 predicting historic high sea surface temperatures, scientists anticipate a larger-than-normal influx of juvenile great white (white) sharks along the California coast. Instead of gathering off the coast of Baja, warm anomalies push these juveniles northward toward Southern and Central California earlier in the year as they search for nearshore water temperatures in their comfort range. In California, adult great white sharks aggregate seasonally, primarily in the colder waters north of Point Conception, following an annual large migration from the north central pacific.
During the fall months (Sharktober) scores of adult white sharks return to gather at the Farallon Islands and rocky headlands of central California to hunt marine mammals, such as fur and harbor seals, California sea lions and especially northern elephant seals. While adult white sharks are endothermic “warm blooded” and can tolerate a range of temperatures from tropical to temperate. Their major prey source is the marine mammals that frequent high productivity coastal upwelling areas like the central California coast. These pinnipeds (seals and sea lions) feed in the rich coastal upwelling zone, and haul out on rocky outcrops to rest, warm and give birth. Much of the sealʻs diet is composed of fish that consume plankton like sardines and anchovies, known as forage fish. During years of weak upwelling, plankton abundance declines and the forage fish populations are closely linked.
Without forage fish, these pinnipeds are forced to travel further or dive deeper into colder water to forage, leading to nutritional stress and lowering the weaning weights for pups. As pinnipeds alter their foraging distribution or decline in number, the adult white sharks that rely on them are forced to shift their own hunting grounds or alter their residency times around the Farallones to survive.
Since the 2015 marine heatwave, warming sea temperatures provided a new haven for Californiaʻs juvenile white sharks northward. Prior to 2014, the northernmost edge of the juvenile white shark nursery range was located around Point Conception near Santa Barbara (34° N). However, the unprecedented 2014–2016 North Pacific marine heatwave known as “The Blob” drastically shifted the range northwards.
Warmer Sea Temperatures Lead to Demographic Shifts
In August 2020, water temperatures in northern Monterey Bay spiked to 21°C (69.8 F)—well above the historical 13°C ( 55F) average. This established a temporary “Goldilocks zone” for juvenile white sharks bridging the wamer waters south of Point Conception as far north as Santa Cruz. Young white sharks are skinny, and have a high surface/volume ratio making them less tolerant of colder water. As sharks mature and gain girth, their surface-area-to-volume ratio drops. This allows adults to utilize regional endothermy to keep their internal muscles and organs warmer than the surrounding ocean, freeing them to hunt in much colder waters- like the cold upwelling zones off San Francisco.
Juvenile white sharks are highly sensitive to temperature and prefer a temperature range of about 60°F to 72°F (16°C to 22°C). Seeking cooler waters to maintain their preferred temperatures, juvenile white sharks expanded their range hundreds of miles north to Bodega Bay (38.5° N) during the last heatwave. Since then, their northern limit has hovered near Monterey Bay (36° N). Researchers noted a new, seasonal cohort of juvenile sharks residing in nearshore waters off Aptos, California—an area historically too cold for young sharks.
Protected since 1993 following a period of overfishing, and prey and habitat loss, the northeastern Pacific population of white sharks along the west coast (that includes Baja California and the Sea of Cortez) is slowly recovering. The 2026 El Niño event could open the door to more juvenile and sub-adult white sharks to shift their range northwards, particulalry into embayments like Morro Bay, Port San Luis, the Monterey Bay, and even the San Francisco Bay.
Warmer conditions also attract non-native fish from Mexican waters including subtropical species like mahi-mahi and yellowfin tuna. Following these, hammerhead sharks and mako sharks all shift their ranges northwards into the Southern California bight. Even more aggressive species like bull sharks and tiger sharks might visit Southern California waters this year. To the north, thresher sharks and blue sharks are all likely to maintain a presence in the Gulf of the Farallones, and even a mako shark might be observed following pacific albacore as they experience a northward and coastal shift during El Niño events.
More young white sharks does not necessarily mean more human – shark interactions, or “shark attacks.” The preferred prey of young sharks is fish, especially stingrays. However, the warmer waters will benefit rays too and may increase nearshore human interactions with sharks and rays. Learn what you can do to minimize your risk of a shark bite this summer.
There is hope that the coastal upwelling this summer may stave off some of the weakening upwelling cycle. It remains to be seen what impacts this year’s El Niño will bring to our California Coastal Upwelling ecosystem, including the sharks, and it could be exciting!
References
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All work ©David McGuire, Shark Stewards