Stejneger's beaked whale
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Stejneger's beaked whale (Mesoplodon stejnegeri), also known as the Bering Sea beaked whale or the saber-toothed whale, is a relatively unknown member of the genus Mesoplodon inhabiting the North Pacific Ocean. Leonhard Hess Stejneger collected the type specimen (a beach-worn skull) on Bering Island in 1883, from which Frederick W. True provided the species' description in 1885. In 1904, the first complete skull (from an adult male that had stranded near Newport, Oregon) was collected, which confirmed the species' validity.<ref>True, F.W. 1910. An account of the beaked whales of the family Ziphiidae in the collection of the United States National Museum, with remarks on some specimens in other American museums. Washington: Government Printing Office.</ref> Limited data exists regarding the global population of Stejneger's beaked whales, primarily due to the infrequency of sightings at sea. In general, beaked whales are elusive and wary, and the species within this family do not have prominent physical traits in comparison to other beaked whales.<ref name=":0">Template:Cite web</ref> This makes it challenging to identify them individually.
Description
The body of this species is typical for the genus Mesoplodon, long and tapering at both ends. The snout is of medium length, and the mouthline forms an arch, though much smoother than in other species. This species is distinguishable from other Mesoplodon via tooth shape, which got them the name of saber-toothed whale, and position.<ref name=":1">Template:Cite web</ref> The teeth of the males are much larger than those of most other Mesoplodon species, and point forwards and inwards right in front of the apex. Only strap-toothed whales and spade-toothed whales have longer teeth. Scarring also frequently occurs due to fighting amongst individuals over mates, with the wounds caused by the teeth while the mouth remains closed.<ref name=":1" />
Their coloration ranges from grey to black with a light ventral side, though males are usually darker. The coloration darkens with age, but females also have a light pattern on the bottom of the flukes that becomes more apparent with age. Their length is at least Template:Cvt for males and Template:Cvt for females, and they can weigh up to 3,527 pounds.<ref name=":0" /><ref name=":1" /> They are likely around Template:Cvt in length when born.Template:Citation needed
Population and habitat
This is the northernmost species of beaked whale in the Pacific Ocean, ranging up into the Bering Sea. They are distributed along both sides of the Pacific to Miyagi Prefecture, Japan, Oregon, British Columbia, and southern California. They may migrate south in winter. These animals are rarely spotted, and they inhabit the deep water far away from the shoreline.<ref name=":1" /> They usually inhabit depth between 2,500-5,000 feet.<ref name=":1" /> They also typically prefer cooler waters.<ref>Template:Cite web</ref>
Behavior and ecology
These whales are diurnal and migratory, typically found in pods of two to six, but some research shows they have been found in pods from as low as five to as many as fifteen. The groups may have age and sex segregation. They are very social animals and swim side by side, often making contact, surfacing and diving together. They are known for their deep diving abilities, but whether they are benthic or pelagic divers is unknown. They can swim at speeds of 5,5 to 7,5 km/h, with top speeds reaching roughly 11 km/h.<ref name=":1" /> A typical behavior involves a series of shallow dives followed by a longer dive lasting about 10 to 15 minutes, reaching depths of up to 4,920 feet.<ref name=":0" /> Additionally, while in pods, members often take 2 to 3 synchronized low blows, followed by vocalizations described as "roars, lowing, and sobbing groans."<ref name=":2">Template:Cite journal</ref> These vocalizations can be used for reproduction, danger alarms, or general communication between whales. All of their communication is tactile and chemical based and they have an average lifespan of 35 years old.<ref name=":1" />
Diet
These whales feed on deep-water squid and other cephalopods and fish. In one instance, a school of salmon was seen being pursued by M. stejnegeri off the coast of Japan.<ref name=":2" />
Reproduction
Nothing is known about the reproduction of this species. It is speculated that they have an average number of one offspring and births happen in the spring and summer.<ref name=":2" /> They may become sexually mature when they reach 14.8 feet, but sexually mature females can give birth to a 175 pound calf at about 8 feet long.<ref name=":0" /> During mating, adult males fight each other extensively, and some specimens have been found with healed jaw fractures.Template:Cn
Conservation
This species has been occasionally hunted in Japan in the past, and caught in salmon drift nets. The flesh of this whale is deemed enjoyable when cooked, though the Makah Indians in Washington have noted instances of diarrhea after consuming its blubber and meat. A limited number of these whales are caught by commercial fisheries, mainly in Japan.<ref name=":1" /> There have been instances where Stejneger's beaked whales have consumed hazardous materials, including plastic bags and strings, so they are at risk for marine debris.<ref>Template:Cite journal</ref>
Additionally, as deep-diving cetaceans, these whales rely on sound for feeding, communication, and navigation. Noise pollution from human activities, such as active sonar or seismic surveys, can disrupt their natural behaviors and forced them to abandon critical habitats.<ref name=":0" /> Loud anthropogenic sounds may also cause these whales to surface too quickly, resulting in decompression sickness or even death. They are of a conservation concern and are listed on the IUCN Red List as near threatened.<ref>Template:Cite journal</ref> In the United States, all Stejneger's beaked whales are protected under the Marine Mammal Protection Act. Efforts to conserve this species include reducing encounters with fishing gear and mitigating the impacts of vessel disturbances, noise pollution, and other human-related threats.<ref name=":0" />
See also
References
Further reading
- Encyclopedia of Marine Mammals. William F. Perrin, Bernd Wursig, and J.G.M Thewissen, editors. Academic Press, 2002. Template:ISBN
- Sea Mammals of the World. Randall R. Reeves, Brent S. Steward, Phillip J. Clapham, and James A. Owell. A & C Black, London, 2002. Template:ISBN