Sowerby's Beaked Whale
About the Species
Sowerby's beaked whales, sometimes known as the "North Atlantic beaked whale," are little known members of the beaked whale family, Ziphiidae. The first beaked whale to be discovered, this species prefers the deep, cold, temperate and subarctic waters throughout the North Atlantic Ocean, but has also been reported near the ice pack. Their scientific name, bidens, is derived from the Latin words bi for "two" and dens for "teeth" and refers to the pair of visible teeth that erupt from the lower jaw of mature males.
The beaked whale family is cryptic and skittish. Due to the rarity of sightings at sea, there is little information on the abundance of Sowerby’s beaked whales worldwide.
Like all marine mammals, Sowerby’s beaked whales are protected under the Marine Mammal Protection Act. They face threats from entanglement in fishing gear and human-caused noise.
NOAA Fisheries estimates population size for Sowerby’s beaked whales in its stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. There is little information on the abundance of this species worldwide. Thus, data are insufficient to estimate population trends.
CITES Appendix II
- Throughout Its Range
- Throughout Its Range
As adults, Sowerby's beaked whales can reach estimated lengths of 14.5 to 21 feet and weigh 2,200 to 2,900 pounds. Males, which are generally larger, can be distinguished from females and juveniles by a pair of visible teeth that erupt from their slightly arched lower jaw. Females and juveniles also have teeth, but they remain hidden beneath the gum tissue, and their jawline is straight.
Sowerby's beaked whales have a small- to medium-sized body with a very long, slender beak relative to other beaked whales, as well as a bulge on the forehead area. The beak often emerges at a steep angle when surfacing. They have a small, wide-based, slightly hooked dorsal fin located about two-thirds down their back. Most of their body is charcoal gray with a pale underside, and calves are generally darker than adults. The lower jaw is usually light gray or white. This species has less visible scarring than most other beaked whale species.
Behavior and Diet
Sowerby's beaked whales are usually found individually or in small, closely associated groups averaging between three and 10 individuals. Regular dives range from 10 to 15 minutes, but dives of at least 28 minutes and reaching depths up to 4,920 feet have been recorded. While diving, they use suction to feed on small, deep-sea fish and cephalopods (e.g., squid) in deep waters. When surfacing, this species often lifts its head up out of the water at a 45-degree angle.
Many species of beaked whales (especially those in the genus Mesoplodon) are very difficult to distinguish from one another (even when dead) because they lack easily discernible or apparent physical characteristics. At sea, they are challenging to observe and identify to the species level because of their cryptic, skittish behavior; low profile; and a small, inconspicuous blow at the water’s surface. Therefore, much of the available characterization for beaked whales is to the genus level only, and there is relatively little information about most individual species.
Where They Live
Sowerby's beaked whales prefer the deep, cold temperate and subarctic waters off the continental shelf edge of the North Atlantic Ocean but have also been reported near the ice pack. They are distributed throughout the North Atlantic Ocean (30° to 71° North), ranging from the Norwegian Sea, Labrador Sea, Iceland, and Baltic Sea to the north, and waters off the northeast United States, Madeira, and the Canaries to the south.
Sowerby’s beaked whales may be more common in the eastern than the western North Atlantic Ocean. However, they rarely occur in the Mediterranean Sea. Strandings have occurred in Florida and Italy, but these areas are considered outside their normal range. Their distribution may vary depending on the movements of oceanographic currents. It is unknown whether they undertake seasonal movements or migrations.
Lifespan & Reproduction
Sowerby's beaked whales may reach sexual maturity at about age 7, and their breeding season may be from late winter to spring. A sexually mature female will give birth to a single newborn calf that is about 8 to 9 feet long and weighs about 375 pounds. The estimated lifespan of this species is unknown.
Entanglement in Fishing Gear
Sowerby’s beaked whales have become entangled or captured in commercial fishing gear, such as driftnets and gillnets, off the U.S. Atlantic and Canadian coasts.
Deep-diving cetaceans like Sowerby's beaked whales rely on sound to feed, communicate, and navigate in the ocean. Sound pollution threatens them by interrupting their normal behavior and driving them away from areas important to their survival.
In the Spotlight
Sowerby's beaked whales, like all marine mammals, are protected under the Marine Mammal Protection Act.
Reducing Interactions with Fishing Gear
Sowerby’s beaked whales are caught as bycatch in fishing gear, such as driftnets and gillnets, off the U.S. Atlantic coast. NOAA Fisheries is committed to minimizing bycatch in U.S. fisheries to ensure that fisheries remain sustainable and to protect species such as the Sowerby’s beaked whale.
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings including all whales. When stranded animals are found alive, NOAA Fisheries and our partners assess the animal’s health and determine the best course of action. When stranded animals are found dead, our scientists work to understand and investigate the cause of death. Although the cause often remains unknown, scientists can sometimes attribute strandings to disease, harmful algal blooms, vessel strikes, fishing gear entanglements, pollution exposure, and underwater noise. Some strandings can serve as indicators of ocean health, giving insight into larger environmental issues that may also have implications for human health and welfare.
Marine Mammal Unusual Mortality Events
Sowerby’s beaked whales have been part of a declared unusual mortality event in the past. Under the Marine Mammal Protection Act, an unusual mortality event is defined as "a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response." To understand the health of marine mammal populations, scientists study unusual mortality events.
Addressing Ocean Noise
NOAA Fisheries is investigating all aspects of acoustic communication and hearing in marine animals, as well as the effects of sound on beaked whale behavior and hearing. For example, the use of at least some types of shipboard echosounders decreases the acoustic detection rates of multiple species of beaked whales, indicating that they change their behavior when they hear these echosounders. In 2018, we revised the technical guidance for assessing the effects of anthropogenic sound on marine mammal hearing.
Sowerby’s beaked whales are protected under the MMPA.
Key Actions and Documents
NOAA Fisheries conducts a variety of research on the biology, behavior, and ecology of Sowerby’s beaked whales. The results of this research are used to inform management decisions and enhance protection efforts for this species.
Determining the size of Sowerby’s beaked whale populations helps resource managers gauge the success of NOAA Fisheries’ conservation measures. Our scientists collect and present these data in annual stock assessment reports.
NOAA Fisheries conducts research cruises to collect information on beaked whale stocks, including distribution, habitat preferences, and feeding ecology. These studies also help us estimate the abundance of beaked whales. Information from this research can be used in management actions to protect these animals.
Our research is also focused on acoustics—using underwater sound to learn more about species. We study the basic acoustic behavior of cetaceans and fish, mapping the acoustic environment and finding better ways to study cetaceans using passive acoustic technologies. For example, we tow hydrophones behind ships to acoustically detect and locate Sowerby’s beaked whales during surveys. We also use archival bottom-mounted recorders to monitor long-term occurrence of the species at specific recording sites. Our acoustic research also assesses the degree to which human-caused activities are changing the underwater soundscape, how these changes may potentially impact marine animals, and what measures can be taken to mitigate these potential impacts.