Why do oarfish come ashore? Evidence behind the explanations

A beach encounter is an unusual sample

Oarfish are long, ribbon-shaped oceanic fishes. Seeing one at a beach samples an unusual part of an animal’s life, rather than showing its ordinary habitat or behavior. The Florida Museum profile describes *Regalecus glesne* swimming with waves along its long dorsal fin while its body remains relatively straight. It also describes a filtering mouth. Those details help explain the fish’s form and feeding anatomy, but they do not by themselves explain why a particular animal reached shore. [1]

The Florida Museum profile reports surface or beach encounters after storms and when animals are injured or dying. Scripps discusses injury, illness and disorientation as possible explanations for beach encounters. A general mechanism, however, is not a diagnosis: a storm association does not establish that a storm caused an individual encounter, and a fish found on shore is not automatically old, suicidal or killed by decompression. [1] [2]

What a measured case can—and cannot—tell us

A useful comparison is the adult male short-crested oarfish found at La Jolla on August 10, 2024. Scripps identified it as *Regalecus russellii*. Researchers measured 3.735 m total length and 33.7 kg at necropsy on August 16. The fish was in good external condition, yet its cause of death remained unresolved. The find date, necropsy date, and report date are different: Scripps reported the investigation on August 22. [2]

That case shows why appearance alone is weak evidence about cause. Even a measured animal examined by researchers can leave the central question unanswered. The carcass nevertheless supplied samples for genomic, feeding, reproductive, and contaminant investigations. Such samples allow follow-up work; their existence does not mean those investigations have already established a cause of death. [2]

Local geography may also shape what gets recorded. Scripps notes that submarine canyons near La Jolla bring deep water close to shore, a possible contributor to local records. “Possible contributor” is appropriately limited: it does not demonstrate that the canyon caused the 2024 death or that canyon geography explains every stranding elsewhere. [2]

Testing the earthquake story

A sighting followed by an earthquake somewhere is not evidence that the fish predicted it. To evaluate a prediction claim, a test would need a defined geographic area, a time window, and a comparison rate: how often relevant earthquakes occur in that area and window without a preceding oarfish report. Otherwise, choosing a later earthquake after seeing a report can make coincidence look meaningful. [2]

Scripps cites a 2019 Japanese analysis that found no relationship between reported ribbonfish and oarfish strandings and earthquakes. That is evidence against using these strandings as a warning signal. It does not establish the cause of any individual stranding, and a fish nickname or striking appearance is not a substitute for official hazard information. [2]

Keep the species and life histories distinct

The Florida Museum’s profile concerns *R. glesne*, while the La Jolla necropsy concerned *R. russellii*. The profile describes pelagic eggs and larvae that resemble miniature adults; it should not be silently treated as a reproductive account of the La Jolla individual or every oarfish species. Local reproductive timing and species differ, so observations from one fish or profile have limits when generalized. [1]

Similarly, the 2024 Scripps release stated that 20 California records had been documented since 1901. That is a historical count reported in that release, not a live, current total. Strandings are rare events and reporting records are not necessarily a complete census of animals at sea. [2]

Read the evidence in order

For any stranding, separate what was observed from what is inferred: species identification, measured length and mass, external condition, examination findings, and any established cause. The La Jolla example supplies a date, species, total length, mass, and necropsy; it still leaves the cause unresolved. That is a stronger and more useful conclusion than turning a plausible explanation into certainty. [2]