Stejneger's beaked whale
Mesoplodon stejnegeri
A shy, deep-diving whale of cold North Pacific water that is almost never seen at sea. No sighting is a promise.
Near Threatened (IUCN, 2020) means it is close to qualifying as threatened with extinction. Numbers are unknown.
Length
Adults reach about 5.7 m (18.7 ft); stranded adults in Japan averaged about 4.7 m (15.3 ft) for males and 4.9 m (15.9 ft) for females
Weight
Up to about 1,600 kg (3,527 lb); weighed Japanese adults averaged about 890 kg (1,950 lb) for 5 males and about 1,220 kg (2,690 lb) for 2 females, so the sample is small
Next to a person
About three times as long as an adult is tall, and as heavy as roughly 10 to 20 adults
What it eats
Small deep-water fish, tunicates and squid, caught by suction during deep dives.
Around people
Shy, give space
How it lives
Stejneger's beaked whales travel in small groups of about 2 to 15. They make deep dives of about 10 to 15 minutes, reaching depths of up to about 1,500 m (4,920 ft). They are thought to live at least 35 years. Newborns found stranded in Japan measured about 1.9 m (6.3 ft), and most were found from early March to May.
Where it goes
Movements are poorly known. Stejneger's beaked whales live in the cool deep waters of the North Pacific, from the Bering Sea and Aleutian Islands to California and from Kamchatka and the Sea of Japan. They prefer deep water at or beyond the continental slope. The sources read do not describe a migration route.
We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.
Populations
There is no abundance estimate, because sightings at sea are so rare. The United States recognises one Alaska stock. The IUCN lists the species as Near Threatened (2020). It is on CITES Appendix II and protected under the US Marine Mammal Protection Act. Threats include entanglement in drift and gill nets, a Japanese beaked whale hunt, marine debris and ocean noise.
Meet it respectfully
Beaked whales are shy and rarely come to the surface for long. If one appears, keep your boat slow and well back, keep noise low and let it move on its own terms. Never chase, approach, touch, feed or bait it. Sudden loud noise can disturb deep-diving whales. In US waters the Marine Mammal Protection Act applies, and rules differ by place, so follow local rules and your guide. A sighting is never guaranteed.
Fun fact
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Eight adult females stranded on Adak Island, Alaska, in August 2018, the largest known mass stranding of the species.
In Japan, 120 strandings were reported between 1999 and 2011, mostly on the Sea of Japan coast.
It can dive for 10 to 15 minutes to depths of about 1,500 m.
Stejneger's beaked whale in the Ocean Atlas
Places we have researched where this animal is recorded. It is never guaranteed, and some places are for watching from the boat only.
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Japan
United StatesSources for this page
- GBIF (IUCN Red List category), 2026
- Wikipedia, 2026
- NOAA Fisheries, 2026
- Animal Diversity Web, 2026
- Pathological findings of Stejneger's beaked whales stranded in Japan, PMC, 2015
- NOAA Fisheries, Adak mass stranding, 2026
Facts checked 5 October 2026. Photos: Unsplash licence, or Creative Commons as shown on each photo.
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