Blainville's Beaked Whale

Blainville's beaked whales are little-known members of the beaked whale family, Ziphiidae. Sometimes known as the "dense-beaked whale," this species lives in tropical to temperate waters worldwide. It istypically found in deep, offshore waters (656 to 3,281 feet) off the continental shelf and often associated with steep underwater geological structures such as banks, submarine canyons, seamounts, and continental slopes.

There is little information on the abundance of Blainville’s beaked whales worldwide, though they are considered to have the most extensive distribution of any whale in the Mesoplodon genus. The beaked whale family is cryptic and skittish, and distinguishing between species in the field can be challenging. 

Like all marine mammals, Blainville’s beaked whales are protected under the Marine Mammal Protection Act. They face threats from entanglement in fishing gear, ingestion of marine debris, and human-caused noise. Blainville’s beaked whales are considered “data deficient” by the International Union Conservation of Nature list of threatened species, meaning that there is not enough information to assess their population status. 

As adults, Blainville's beaked whales can reach lengths of approximately 15 to 20 feet and weigh 1,800 to 2,300 pounds. Mature males can be easily distinguished from females and juveniles by a pair of large, visible, tusk-like teeth that erupt and point forward from their heavily arched lower jaw. These tusk-like teeth are sometimes covered with barnacles. Females and juveniles also have teeth, but they remain hidden beneath the gum tissue of the mouth, and their jawline is less curved.

Blainville's beaked whales have a medium-sized, round body with a small, wide-based, slightly hooked dorsal fin located far down the animal's back. They also have a low, sloping, indistinct forehead (or melon). Their coloration varies from dark-gray to brownish and bluish. The animal’s face and underside are pale gray or white, giving it a counter-shading appearance. The skin may appear wrinkled on the dorsal area and is covered with linear and oval-shaped scars and other markings. Individuals, especially mature males, accumulate scars and scratches with age. Diatom (microscopic planktonic algae) infestation may discolor areas of the skin.

Blainville's beaked whales are usually found individually or in small social groups averaging between three and seven animals, but they have been occasionally seen in larger groups of up to 12 animals. Groups may consist of various combinations of age and sex and/or be segregated depending on age or sex. Adult populations in productive waters over the continental shelf (e.g., the Bahamas) may be grouped in harems that consist of several adult females with a single adult mature male. Males commonly battle over access to females, which is probably the cause of the long linear, scars seen on individuals.
 
Like other beaked whales, Blainville’s beaked whales are deep divers. Regular dives range from 20 to 45 minutes and commonly reach depths of at least 1,600 to 3,300 feet, but dives of over 54 minutes and up to 4,600 feet have also been recorded. While diving, they use suction to feed on small fish and cephalopods (e.g., squid) in deep water.

The estimated lifespan of Blainville's beaked whales is unknown. They may reach sexual maturity at about 9 years of age. A sexually mature female will give birth to a single newborn calf that is about 6 to 8.5 feet long and weighs about 130 pounds.

Entanglement in Fishing Gear

Unidentified beaked whales (which may include Blainville's beaked whales) have been entangled or captured in the pelagic drift gillnet fishery off the U.S. Atlantic coast. Japanese fishing boats in the Indian Ocean (off of Seychelles and western Australia) have also incidentally taken Blainville's beaked whales, and they have been occasionally caught as bycatch in hunts targeting small cetaceans.

Marine Debris

Some beaked whales have died from ingestion of marine debris.

Ocean Noise

Deep-diving cetaceans like Blainville’s beaked whales use sound to feed, communicate, and navigate in the ocean. Recently, strandings of this species in the Bahamas because of acoustic trauma have been associated with use of active sonar during naval military activities and exercises.  Sound pollution threatens Blainville’s beaked whales by interrupting their normal behavior and driving them away from areas important to their survival, such as breeding and feeding waters.