Stejneger's Beaked Whale

About the Species

Stejneger's beaked whales, sometimes known as the "Bering Sea beaked whale" or "saber-toothed whale," are little known members of the beaked whale family (Ziphiidae). They receive their common and scientific name from Leonhard Stejneger, a naturalist and curator at the Smithsonian Institution, who first described the species from a single skull discovered on Bering Island in 1885. This species prefers the cold, temperate, and subarctic waters of the North Pacific Ocean and is generally found in deep, offshore waters on or beyond the continental slope.

There is little information on the abundance of Stejneger's beaked whales worldwide due to the rarity of sightings at sea. Overall, the beaked whale family is cryptic and skittish, and individual species lack any easily discernable physical characteristics, making it difficult to distinguish between them.

Although they face threats from entanglement in fishing gear, human-caused noise, and marine debris, Stejneger's beaked whales in the United States are not endangered or threatened. Like all marine mammals, they are protected under the Marine Mammal Protection Act.

Status

NOAA Fisheries estimates population size for each stock of Stejneger's beaked whale in its stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. There is little information on the abundance of this species worldwide due to the rarity of sightings at sea. Thus, data are insufficient to estimate population trends.

Protected Status

Appearance

As adults, Stejneger's beaked whales can reach lengths of about 18.7 feet and weigh up to 3,527 pounds. Females may be slightly larger than males. Males can be easily distinguished from females and juveniles by a pair of large, visible, forward-pointing, tusk-like teeth that erupt from their arched lower jaw. Females and juveniles also have teeth, but they remain hidden beneath the gum tissue of the mouth, and their jawline is generally less curved.

Stejneger's beaked whales have a relatively medium-sized, round body with a small, wide-based, slightly hooked dorsal fin located about two-thirds down their back. They have a low-sloping, indistinct forehead (known as a melon). Their coloration varies from dark gray to brownish and black. A dark cap that extends across the top of the head from eye to eye, and the lower jaw is usually white or pale gray. The skin may be covered with linear and oval-shaped scars and other markings. Individuals, especially mature males, accumulate more scars and scratches with age. Mature males will battle each another for access to females.

Behavior and Diet

Stejneger's beaked whales are usually found individually or in small, tight social groups averaging between five and 15 individuals. These groups may contain animals of mixed sexes, ages, and life stages, or they can be segregated. Like most beaked whales, this species is difficult to approach and generally avoids vessels.

Stejneger's beaked whales usually make five to six shallow dives followed by a longer dive that lasts 10 to 15 minutes and may reach depths of 4,920 feet. While diving, they use suction to feed on small deep-water fish, tunicates, and cephalopods (e.g., squid).

Where They Live

Stejneger's beaked whales prefer the cold, temperate, and subarctic waters of the North Pacific Ocean. They are generally found in deep, offshore waters between 2,500 and 5,000 feet on or beyond the continental slope.

Stejneger's beaked whales have a distribution throughout the North Pacific that includes California, the Aleutian Islands, the southwest Bering Sea, Kamchatka, the Okhotsk Sea, and the Sea of Japan. Strandings of this species have commonly occurred in the Aleutian Islands of Alaska and on the west coasts of Japan. Scientists speculate that Stejneger's beaked whales may migrate north in the summer. Information on their distribution mostly comes from stranding records.

Lifespan & Reproduction

Stejneger's beaked whales may become sexually mature when they reach about 14.8 feet in length. A sexually mature female will give birth to a single calf that is about 7.2 to 8 feet long and weighs about 175 pounds. The calving season is generally between spring and autumn. The estimated lifespan of this species is at least 36 years.

Threats

Entanglement in Fishing Gear

Stejneger’s beaked whales can become entangled or captured in commercial fishing gear, particularly in driftnet and gillnet fisheries in the Sea of Japan and off the west coast of North America.

Commercial Whaling

This species is hunted in a Japanese fishery that targets beaked whales.

Marine Debris

Stejneger’s beaked whales are known to have ingested dangerous items such as plastic bags and string.

Ocean Noise

Deep-diving cetaceans like Stejneger’s beaked whales use sound to feed, communicate, and navigate in the ocean. Sound pollution threatens them by interrupting their normal behavior and driving them away from areas important to their survival.

Scientific Classification

Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Cetacea
Family	Ziphiidae
Genus	Mesoplodon
Species	stejnegeri