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Blainville’s Beaked Whale (Mesoplodon densirostris)

The Blainville’s beaked whale is one of the least well-known beaked whale species due to the fact that they live far offshore in deep waters. Blainville’s beaked whales are also cryptic and fairly shy – they often avoid boats, and they can be easily confused with other species when in the field, making it even harder to identify and track them in the wild. These whales are often found in tropical to temperate waters around the world, mostly living along the continental shelf where the water is between 650-3,000 feet deep! It is thought that they have one of the widest distributions of any of the beaked whales, and here in the U.S. we have three known stocks: Hawaii, Northern Gulf of Mexico, and the Western North Atlantic stocks.

Blainville’s Beaked Whale. Photo credit: NOAA Fisheries

Physically, the Blainville’s beaked whale is medium in size, growing to about 15-20 feet and up to 2,300 lbs. Their round bodies have a small, wide-based dorsal fin that is slightly falcate (curved), and they can range from dark gray to brown or even bluish in color. Males have a pair of visible, tusk-like teeth that erupt and point forward from their arched lower jaw. Because these tusks cannot be retracted, they can even become encrusted with barnacles as the whales age! Speaking of age, Blainville’s skin becomes covered in linear and oval-shaped scars which also accumulate as they age. The females and juveniles have teeth too but not the identifying external teeth, and often have a less pronounced curve to their jaw as well. The lifespan of these whales is unknown, but it is thought they become sexually mature at around 9 years old.

In terms of food, Blainville’s beaked whales will suction up cephalopods and small fish at depths of up to 3,000 feet (the deepest dive made by a Blainville’s beaked whale was 4,600 feet!), and can dive for up to 54 minutes. They have unique physiological systems that help prevent them from getting the bends in such deep water.

What about their social life…do they have a social life!? Turns out they do! Although Blainville’s beaked whales are typically seen individually or in small groups of 3-7 animals, they have been observed in groups of up to 12. It is believed they will segregate based on age or gender, and have been documented moving in “harems” consisting of females and one reproductively active male. The males can be quite aggressive with one another, and often the scarring seen on the bodies of older animals comes from fighting with other whales.

Threats to this species include entanglement in fishing gear, ingestion of marine debris, and acoustic trauma due to naval sonar and military exercises. This last threat has even made the news over the last 10 years or so, with several mass strandings of beaked whales occurring following known military exercises. Although we’re not 100% sure exactly what causes mass strandings, is believed that the high-pitched tones of the sonar could sound like killer whales – the main predator of beaked whales – and startle the whales into surfacing too rapidly. This would lead to nitrogen bubbles forming in the blood which can ultimately cause death.

Baird’s Beaked Whale (Beradius bairdii)

The largest member of the beaked whale family, the Baird’s beaked whale is certainly one for the books! This whale, also known as the “giant bottlenose whale”, can grow to over 26,000 lbs in weight, and up to 35-36 feet in length – that’s BIG! Males are actually slightly smaller than the females.

Baird’s Beaked Whale. Photo credit: NOAA Fisheries

Unlike the Blainville’s beaked whale, both male and female Baird’s beaked whales have external teeth that erupt from the front of their lower jaw once they reach sexual maturity. This occurs at 6-11 years for males, and 10-15 years for females. Their bodies are slender with a small, rounded, triangular dorsal fin. They are dark gray in color, often appearing gray or brownish in color due to mottling, with a lighter underside. Interestingly, a smaller form of Blainville’s beaked whales occur in northern Hokkaido; their dark coloration results in them often being referred to as the “black” form.

Speaking of ranges, Baird’s beaked whales are found throughout the North Pacific Ocean and adjacent seas including the Bering Sea, Sea of Cortez, Sea of Japan, and Okhotsk Sea. They are also found along the U.S. West Coast from California to Alaska. This species typically prefers cold, oceanic waters but is occasionally found along the continental shelf. Like other beaked whales, the Baird’s are renowned divers and can dive for up to 67 minutes, reaching depths of between 2,500 and 4,000 feet! They feed on all sorts of pelagic fish, crustaceans, cephalopods and even sea cucumbers.

Baird’s beaked whales live to 55-85 years, with males often living much longer than females. Due to their large size and social behavior, Baird’s beaked whales are one of the more commonly seen beaked whale species. They often form tight social groups of 5-20 individuals, and have been reported in groups of up to 50 individuals. They are also more active at the surface when they return from deep dives, tail-slapping or spy-hopping, which makes them a little easier to spot!

They migrate seasonally based on surface water temperature: in summer and fall they are typically found near continental slopes or more isolated, restricted waters (such as the Bering Sea); in the winter and early spring when sea temperatures decline Baird’s beaked whales move farther offshore. Because of this we know much less about their over-wintering grounds.

Threats to Baird’s beaked whales include entanglement in fishing gear, commercial whales (in Japan), ocean noise (similar to the Blainville’s beaked whales), ingestion of marine debris, and predation by killer whales which are the main predators of the Baird’s beaked whale.      

cindy.elliser@pacmam.org

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