A deep-sea oarfish, a species that spends its life hundreds of feet below the ocean surface, washed ashore on a beach in Baja California Sur, Mexico, earlier in 2025. The stranding drew crowds of onlookers and reignited a centuries-old belief, rooted in Japanese folklore, that the appearance of this elongated silver fish signals an approaching earthquake or tsunami. Scientists who have studied the species and its strandings say the evidence tells a different story.
Oarfish strandings and the earthquake myth
The oarfish, formally classified as Regalecus glesne, is the longest bony fish in the ocean. It inhabits depths below 600 feet and is almost never seen alive by humans, which has fed its mystique for generations. In Japanese tradition, the fish is known as “ryugu no tsukai,” or messenger from the sea god’s palace. When one appears on shore, some communities interpret it as a warning of seismic disaster. That belief spread rapidly online after the Mexico stranding, with social media users speculating about earthquake risk across the Pacific coast.
A research group from Tokai University and Shizuoka Prefectural University examined this claim directly. The team compiled historical records of deep-sea fish appearances and compared them against seismic data. Their conclusion, published in a peer-reviewed study, was blunt: the idea that oarfish strandings predict earthquakes is a superstition. The researchers found no statistical correlation between the two phenomena. No pattern in timing, geography, or frequency connected fish strandings to subsequent seismic events.
Folklore, however, is resilient. The striking appearance of an oarfish-an undulating ribbon of silver that can stretch longer than a bus-offers a vivid image that easily attaches to fears about natural disasters. Viral posts often pair photos of stranded specimens with lists of past earthquakes, implying a connection that the data do not support. Scientists caution that this kind of pattern-seeking is a classic example of confirmation bias: people remember the times a rare event seemed to precede a disaster and forget the many times it did not.
What oceanographers found inside a stranded oarfish
Separate from the Mexico event, researchers at the Scripps Institution of Oceanography at UC San Diego recovered a different oarfish specimen off the Southern California coast and brought it into the lab for detailed study. The team, which included staff from the Marine Vertebrate Collection, performed a necropsy and collected tissue samples for genomic analysis. Their goal was not to test earthquake theories but to learn basic biology about a species that scientists still know remarkably little about. Because oarfish live at such extreme depths and rarely surface intact, each specimen represents a rare chance to study anatomy, diet, and genetics.
Inside the laboratory, researchers documented the internal organs, examined the stomach contents, and preserved muscle and fin tissue. These samples can reveal what the fish had been eating, how fast it was growing, and how its physiology adapts to the crushing pressure and low light of the deep sea. Genetic sequencing, in turn, can clarify how oarfish are related to other deep-sea species and whether distant populations belong to a single global species or several closely related lineages.
The Scripps work also points toward oceanographic explanations for why oarfish occasionally wash ashore. Strong upwelling events along the Pacific coast can push cold, nutrient-rich water toward the surface, disrupting the deep layers where oarfish typically swim. When these currents shift, weakened or disoriented fish can be carried into shallower water and eventually onto beaches. Seasonal upwelling is especially pronounced along the Baja California peninsula, where cold water from the deep Pacific rises close to shore during certain months. This mechanism offers a plausible, testable explanation for strandings in the region, one grounded in physical oceanography rather than seismology.
Other environmental stresses could play a role as well. Sudden changes in temperature, low-oxygen zones, or exposure to pollutants might weaken deep-sea animals that are already living near the limits of their tolerance. A compromised oarfish may swim erratically or lose its ability to maintain depth, making it more likely to be caught in surface currents or waves. In that scenario, the fish functions less as a harbinger of disaster and more as a casualty of shifting ocean conditions.
The Florida Museum of Natural History at the University of Florida notes that live oarfish observations are extremely rare precisely because the species inhabits such deep, remote waters. The museum’s species profile documents that the fish can grow to extraordinary lengths, making any beach appearance a dramatic spectacle that naturally attracts attention and speculation. For biologists, though, each specimen is primarily a data point: a chance to refine estimates of maximum size, growth rate, and distribution.
Gaps in the evidence and what to watch
Several questions about the Mexico stranding itself remain unanswered. No primary documentation, such as necropsy results, tissue samples, or official reports from Mexican marine authorities, has been made publicly available for this particular specimen. The event is known primarily through news accounts and social media posts, not through scientific chain-of-custody records. Without that documentation, researchers cannot determine whether the fish was injured, sick, or affected by environmental conditions before it came ashore.
The Tokai University study, while clear in its conclusion, also has limits. The dataset of historical deep-sea fish appearances relies on records that were not collected under standardized scientific protocols. Sightings compiled from newspapers, museum notes, and local reports may miss many events and overrepresent dramatic cases that drew media interest. Independent replication using a larger, more systematically gathered dataset would strengthen the finding. No peer-reviewed follow-up study has yet been published to extend or challenge the original analysis.
Likewise, the hypothesis that seasonal upwelling drives oarfish strandings along the Baja California coast has not been formally tested in a published study specific to that region. Oceanographic data on upwelling intensity and timing exists, but no research team has yet matched it against a catalog of oarfish stranding dates and locations along the peninsula. That study would be the clearest way to resolve whether these events follow a predictable environmental pattern or occur at random.
For coastal communities along the Pacific, the practical takeaway is straightforward. Earthquake preparedness matters regardless of whether an oarfish appears on a local beach. Seismic risk in the region is real and well documented by geological agencies. But the scientific record, as it stands, offers no reason to treat a stranded fish as a warning system. The next time an oarfish washes ashore, the more productive question will be what ocean conditions brought it there, not what disaster it supposedly predicts.
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*This article was researched with the help of AI, with human editors creating the final content.
