Stejneger’s beaked whales spend nearly their entire lives in deep waters far from shore, diving to extreme depths to hunt squid in the North Pacific. When these elusive animals wash up dead on remote Alaskan beaches, something has gone wrong. Since 1995, researchers have documented dozens of strandings across the state, and the largest known mass stranding of the species killed at least 11 animals on Adak Island in 2018. Federal and state scientists are now working to determine whether the pattern reflects shifting ocean conditions, acoustic disturbance, or factors that have not yet been identified.
Repeated Aleutian strandings signal trouble for a species rarely seen alive
Stejneger’s beaked whales are among the least understood cetaceans on Earth. They are rarely observed at the surface, and most of what scientists know about them comes from dead animals found on beaches. That makes each stranding both a loss and a narrow window into the biology of a species that otherwise stays hidden. The fact that strandings keep occurring along the same stretches of Alaskan coastline, particularly in the eastern Aleutian Islands and parts of Southeast Alaska, has raised pointed questions about what is driving these animals ashore.
A peer-reviewed synthesis published by the Alaska Department of Fish and Game documented strandings of Stejneger’s beaked whales across Alaska from 1995 through 2020. That study noted a male bias among stranded animals and found that stomach contents were dominated by squid, consistent with what is known about the species’ deep-diving foraging behavior. The dietary data matter because squid populations in the North Pacific fluctuate with ocean temperature, and periods of anomalously warm surface water could reduce prey availability in ways that stress deep-diving predators.
One hypothesis that researchers can now begin to test is whether stranding frequency increases during years when warm-water anomalies overlap with declines in squid biomass. NOAA fisheries survey data and stranding coordinates from 2015 onward could be overlaid to look for that correlation. No published analysis has yet confirmed or ruled out the connection, but the data infrastructure exists to do so.
The 2018 Adak Island mass stranding and what necropsies revealed
The single most alarming event in the stranding record occurred on Adak Island in 2018, when responders discovered at least 11 Stejneger’s beaked whales dead or dying on shore. According to NOAA Fisheries, this was the largest known mass stranding of the species ever recorded. The remote location complicated the response, but teams collected tissue samples, recorded body measurements, and performed necropsies on several carcasses to search for clues about the cause of death.
Beaked whale strandings in other parts of the world have been linked to mid-frequency active sonar used in naval exercises. A peer-reviewed synthesis on anti-submarine sonar impacts described a diagnostic condition known as gas and fat embolic syndrome, which has been found in beaked whales stranding near military sonar operations in the Mediterranean and the Canary Islands. Separately, research in the Mariana Islands demonstrated that stranding dates could be matched against independently documented naval activity timelines to test whether sonar was a plausible trigger. No public dataset currently cross-references specific Alaska stranding dates with documented naval sonar exercises in the Gulf of Alaska or Bering Sea, leaving the acoustic-disturbance question open for this population.
Disease, ship strikes, and ingestion of marine debris are also part of the diagnostic checklist for stranding investigators. But direct statements from Alaska-based responders on how they distinguish acoustic trauma from these other causes have not appeared in the published annual reports. That gap limits the public’s ability to evaluate which factors are being ruled in or out for individual cases.
Gaps in post-2020 data leave key questions unanswered
NOAA Fisheries maintains Alaska Region annual stranding reports covering 2023 and earlier years, providing a statewide record of marine mammal deaths and live strandings by species, location, and year. These reports are the primary public tool for tracking whether beaked whale strandings are accelerating, holding steady, or declining. Yet the summary format of the annual PDFs does not include individual case files with full necropsy results and exact coordinates, making it difficult for outside researchers to conduct independent spatial analysis.
Updated stomach-content or stable-isotope analyses for strandings after 2020 have not been released by the state laboratory referenced in the 1995 to 2020 synthesis. Without those data, scientists cannot yet determine whether the dietary profile of recently stranded whales has shifted in ways that would support the warm-water prey-reduction hypothesis. Stable-isotope work, in particular, can reveal whether an animal was feeding at its usual depth and trophic level in the weeks before death, or whether it had been forced to forage in unfamiliar conditions.
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*This article was researched with the help of AI, with human editors creating the final content.
