Gervais' beaked whale. Credit: NOAA Fisheries
Gervais' beaked whale. Credit: NOAA Fisheries
About the Species
Gervais’ beaked whales are little known members of the beaked whale family, Ziphiidae. Sometimes called the "Antillean" or "Gulf Stream beaked whale," this species prefers deep tropical, subtropical, and warm temperate waters of the Atlantic Ocean but is occasionally found in colder temperate seas.
There is little information on the abundance of Gervais’ beaked whales worldwide, though they may be the most commonly sighted species of the Mesoplodon genus off the U.S. Atlantic coast and the Gulf of Mexico. They are also the most common Mesoplodon species to strand on the U.S. southeastern Atlantic coast. The beaked whale family is cryptic and skittish, and distinguishing between species in the field can be challenging.
Like all marine mammals, Gervais’ beaked whales are protected under the Marine Mammal Protection Act. They face threats from entanglement in fishing gear and human-caused noise. Gervais’ beaked whales are considered “data deficient” by the International Union for Conservation of Nature list of threatened species, meaning that there is not enough information to assess their population status.
Population Status
NOAA Fisheries estimates population size for each stock of Gervais’ beaked whale in its stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. There are insufficient data to determine the population trends for this species.
Protected Status
CITES Appendix II
MMPA Protected
Appearance
Even when dead, many species of beaked whales, especially those in the genus Mesoplodon that includes Gervais’ beaked whales, are very difficult to distinguish from one another because they lack easily discernible or apparent physical characteristics.
As adults, Gervais' beaked whales can reach lengths of about 15 to 17 feet and weigh at least 2,640 pounds. Females may be slightly larger than males. Mature males can be distinguished from females and juveniles by a pair of visible teeth that erupt from the front portion of their bottom jaw. Females and juveniles also have teeth, but they remain hidden beneath the mouth’s gum tissue. Gervais beaked whales typically have straight or slightly curved jawlines.
Gervais' beaked whales have a relatively small to medium-size body with a moderately long beak and an indistinct sloping forehead (or melon). They have a small, triangular, wide-based, slightly hooked dorsal fin located far down the back. Their coloring is dark gray or bluish to black, with a paler ventral side. They tend to become darker as they age. Both females and males often have a pronounced dark patch around the eye. Females and young males may have a series of small, faint, wavy stripes down the centerline of the back. Mature males may also have linear scars from battles over females; however, scarring is generally not heavy with this species.
Behavior and Diet
At sea, Gervais’ beaked whales 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.
Gervais' beaked whales are usually found individually or in small closely associated social groups. While diving, they use suction to feed mainly on cephalopods (e.g., squid), mysid shrimp, and small fish in deep water.
Lifespan & Reproduction
The estimated lifespan of this species is at least 27 years but may be up to 48 years. Females may become sexually mature at 15 feet. A sexually mature female will give birth to a single newborn calf that is about 7 feet long and weighs about 176 pounds.
Threats
Entanglement in Fishing Gear
Gervais' beaked whales have been incidentally taken as bycatch in fishing gear, such as pound nets off the U.S. Atlantic coast (e.g., New Jersey) and potentially in driftnets and gillnets.
Hunting
This species may be captured in the Caribbean Sea for food.
Ocean Noise
Deep-diving cetaceans like Gervais’ beaked whales use sound to feed, communicate, and navigate in the ocean. This species may be sensitive to underwater sounds and man-made noise. Sound pollution threatens them by interrupting their normal behavior and driving them away from areas important to their survival, such as feeding and breeding waters.
Scientific Classification
| Animalia |
Chordata |
Mammalia |
Cetacea |
Ziphiidae |
Mesoplodon |
europaeus |
