Longman's Beaked Whale

About the Species

Longman's beaked whales, sometimes known as "tropical bottlenose whales" or "Indo-Pacific beaked whales," are one of the rarest and least known members of the beaked whale family. They generally live in warm, deep, pelagic waters of tropical and subtropical regions in the Indian and Pacific Oceans. Until recently, this species was only known and described from two skulls found on beaches. The first skull was found in Australia in 1882 and described by H.A. Longman—their namesake—in 1926; the second skull was discovered in Africa in 1955. In the early 2000s, genetic and morphological information were used to link these skulls with more specimens of whales that washed ashore and at-sea sightings, thereby providing a more complete description of Longman’s beaked whales as a species.

Longman’s beaked whales are larger than most other beaked whale species and have other discernible physical characteristics that make them relatively easy to identify if spotted in the wild. Little is known about the life history and ecology of this species. Most sightings in U.S. waters have been made offshore of the Hawaiian Islands.

Although they face threats from entanglement in fishing gear and human-caused noise, Longman’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

There is little information on the abundance and population structure of this species worldwide due to the rarity of sightings at sea. An estimate of the population size for the U.S. stock in Hawaiʻi can be found in the NOAA Fisheries’ stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. However, data are insufficient to estimate trends in population size of Longman’s beaked whales in Hawaii.

Protected Status

Appearance

Longman's beaked whales have a large, robust body with a fairly large, hooked dorsal fin located far down their back. This species has dark, small, rounded, narrow flippers that fit into a depression on either side of the body. They have a well-defined forehead—or melon—that is almost perpendicular to their long, tube-shaped beak. A crease may distinguish the melon from the beak. As these whales grow older, the melon develops into a steeper, more bulbous shape that may hang over the beak. Like other beaked whales, they have V-shaped, paired throat creases.  

Longman's beaked whales have a relatively small, low, bushy blow that is usually visible and slightly angled forward. They generally have a darker grayish, bronze, brown, or olive coloration that extends from their blowhole and eye down their back, as well as a facial band. The melon and a defined patch between their neck and abdomen are lighter in color, sometimes described as creamy or pale. The upper jaw of the beak is darker than the lower jaw, which has two conical teeth located at the tip. Adult males have visible, erupted teeth (difficult to see in the field, especially when the mouth is closed) and may have linear and oval-shaped scars (e.g., bites from cookie-cutter sharks and lampreys) along their body.

Behavior and Diet

Longman's beaked whales are usually found in tight groups averaging between 10 and 20 individuals but have occasionally been seen in larger groups of up to 100 animals. They sometimes associate with other marine mammals such as pilot whales, spinner dolphins, and bottlenose dolphins [link to species profiles]. Dives may last from 14 to 33 minutes, and they have been observed swimming rapidly away from survey vessels while at the surface.

Their feeding behavior and prey are generally unknown, but scientists believe they are like that of other beaked whales. Beaked whales are known to dive deep to forage for their food. The analysis of stomach contents from one stranded Longman’s beaked whale implies that cephalopods (e.g., squid and octopus) comprised most of the whale's diet.

Where They Live

Longman's beaked whales live in generally warm (69.8 to 87.8° F), deep (over 3,300 feet), pelagic waters of tropical and subtropical regions in the Indian and Pacific Oceans. Rare sightings have been documented in the eastern tropical Pacific Ocean. Sightings in the waters surrounding the Maldives archipelago and in the western Indian and Pacific Oceans are more frequent.

In U.S. waters, this species has been sighted in the Exclusive Economic Zone around the Hawaiian Islands and in the equatorial tropical Pacific. Strandings have occurred on the coasts of East and South Africa, northern Australia, the Maldives, the Philippines, southern Japan, and Sri Lanka.

Lifespan & Reproduction

Little is known about the reproduction or lifespan of Longman’s beaked whales because of how infrequently they are encountered and their behavior when sighted at sea. A single newborn calf was measured at 9.5 feet.

Threats

Entanglement in Fishing Gear

Longman’s beaked whales can become entangled or trapped in commercial fishing gear. They are sometimes bycaught in fisheries operating in Sri Lanka.

Ocean Noise

This species may be sensitive to underwater sounds and human-made noise. Deep-diving cetaceans like beaked whales use sound to feed, communicate, and navigate in the ocean. Human-made noise, such as military sonar and seismic testing have been implicated in mass strandings of beaked whales, including atypical events involving multiple beaked whale species. 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	Indopacetus
Species	pacificus