By Rebecca Ann Csomos
Geographic Range
Mesoplodon stejnegeri ranges from the Bering Sea to California and Japan, inhabiting only the cool temperate waters of the Northern Pacific Ocean. (Nowak, 1999)
Biogeographic Regions:
pacific ocean 
(native ).
Habitat
Stejneger's beaked whales, Mesoplodon stejnegeri, inhabit the deep waters of the ocean far from the shorelines. These animals are rarely seen at sea. They prefer a habitat with cool water. Mesoplodon stejnegeri has been observed living sympatrically with Hubb's beaked whales where the ranges of the two species overlap off the coast of northern Japan to Oregon and British Columbia. (Loughlin and Perez, 13 December 1985)
These animals are found in the following types of habitat:
temperate ; saltwater or marine .
Aquatic Biomes:
pelagic .
Physical Description
(9.84 to 22.96 ft)
Mesoplodon stejnegeri ranges in length from 3 to 7 m, although they are generally longer than 5.3 m. Females are normally longer than males, and the crania of females are larger than those of males.
Both sexes are uniformly gray to black, with light pale countershading ventrally, although males tend to be more uniformly dark.
Mesoplodon stejnegeri is distinguished from other Mesoplodons by tooth shape and position. Members of this species have two large, exposed, tusk-like teeth on the lower jaw (Nowak 1999). These teeth are also distinctively larger in males.
Scarring, which is present on most M. stejnegeri, results from intraspecific fighting over mates, and is inflicted by the teeth while the mouth is closed (Ridgway and Harrison 1989). (Nowak, 1999; Ridgway and Harrison, 1989)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: female larger, male more colorful, ornamentation .
Reproduction
Nothing is known about the reproduction of M. stejnegeri, although it is speculated that litter size is one and parturition occurs in the spring and summer. (Loughlin and Perez, 13 December 1985)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous .
Although parental investment in this species has not been documented, because these animals are mammals we can infer that females provide a great deal of parental care. They are likely to provide their young with protection as well as food, in the form of milk, until the calves are able to care for themselves.
Parental investment:
pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: female); pre-independence (protecting: female).
Behavior
These beaked whales are deep divers. They swim at 3 to 4 knots on average, with maximum speeds reaching 6 knots. This species usually swims in pods containing 2 to 6 individuals, although groups of 5 to 15 individuals have been observed. Within these social pods, individual whales vary in size, sex, and age. They swim abreast in the pods, touching one another, and they surface and submerge simultaneously. A common pattern of several shallow dives followed by a longer dive of about 10 to 15 minutes has been noted. Also while in these pods, members of this species take 2 to 3 low blows in unison, which are proceeded by sounds described as "roars, lowing and sobbing groans." (Loughlin and Perez, 13 December 1985)
Key behaviors:
natatorial ; diurnal ; motile ; nomadic ; social .
Food Habits
Mesoplodon stejnegeri feeds primarily on deep-water squid. The diet includes both cephalopods and fish. A school of salmon was observed being chased by M. stejnegeri off the coast of Japan, and this species is sometimes trapped in salmon driftnets. (Loughlin and Perez, 13 December 1985)
Primary Diet:
carnivore (molluscivore ).
Animal Foods:
fish; mollusks.
Economic Importance for Humans: Positive
The meat of M. stejnegeri is considered palatable when cooked, but the Makah Indians of Washington reported cases of diarrhea after eating the blubber and flesh. Commercial fisheries, primarily in Japan, take a small number of M. stejnegeri yearly. (Loughlin and Perez, 13 December 1985)
Ways that people benefit from these animals:
food .
Conservation Status
IUCN Red List: [link]:
Data Deficient.
US Federal List: [link]:
No special status.
CITES: [link]:
Appendix II.
These whales are a conservation concern. They are listed as Appendix II by CITES, and Data deficient by IUCN.
Contributors
Rebecca Ann Csomos (author), University of Michigan.
Phil Myers (editor), Museum of Zoology, University of Michigan.
Nancy Shefferly (editor), Animal Diversity Web Staff.
