Marine scientists are forecasting significant shifts in oceanic ecosystems as the National Oceanic and Atmospheric Administration (NOAA) predicts an intensifying El Niño event. This climate pattern is expected to drive unusual marine species, including various sharks and venomous sea snakes, into waters where they are not typically found.
The NOAA has indicated a 63% probability of a "very strong" El Niño occurring between November 2026 and January 2027, potentially ranking among the most significant historical events. El Niño is characterized by the slowing or reversal of east-to-west winds, causing warm water to move eastward toward the U.S. instead of remaining near Asia. This phenomenon typically occurs every two to seven years and can last for nine to 12 months.
Experts anticipate a change in the types of sharks appearing in coastal waters. While juvenile great white sharks have reportedly moved away from traditional nurseries off San Diego, an El Niño could bring species such as tiger sharks, bull sharks, and hammerheads. "Juvenile great white sharks have largely abandoned San Diego’s former nursery, likely due to shifting prey and conditions; an expected El Niño could instead bring more unpredictable species," stated Professor Chris Lowe of California State University, Long Beach.
Beyond sharks, a broader range of marine life is expected to migrate. Mahi-mahi, bluefin tuna, sea turtles, and the yellow-bellied sea snake, described as "highly venomous" and uncharacteristic of California waters, are among the species predicted to enter new territories. Douglas McCauley, director of the Benioff Ocean Initiative at the University of California, Santa Barbara, noted that "some of these kinds of interesting oddities that are never a part of California will become part of this temporarily tropical El Niño-heated California."
Ocean warming associated with El Niño can also accelerate the growth of toxic algae, such as Pseudo-nitzschia, which produces domoic acid. This toxin can be harmful to both humans and wildlife. During a 2015 marine heatwave, known as "The Blob," West Coast fisheries for crab and shellfish were closed due to contamination. The Blob also led to a decrease in squid populations along the California coast, impacting the food chain.
Changes in plankton distribution are also influencing larger marine animals. Research suggests a decrease in deep-water plankton may push whales and other species closer to shore in search of food. This increased proximity to the coast raises concerns about potential entanglements in fishing nets. "Experts are predicting whales may end up getting closer to shore, as they tend to follow their food," the report noted.