Short-beaked dolphin. Credit: NOAA Fisheries
Short-beaked dolphin. Credit: NOAA Fisheries
About the Species
Short-beaked common dolphins are one of the most abundant and familiar dolphins in the world. This highly social and energetic species is widely distributed, preferring warm tropical to cool temperate waters that are primarily offshore. Short-beaked common dolphins are often found in association with underwater ridges, seamounts, and continental shelves where upwelling (a process in which deep, cold, nutrient-rich water rises toward the surface) occurs and prey is abundant.
Short-beaked common dolphins are closely related to—and easily confused with—long-beaked common dolphins. Once thought to be a single species, the two species differ slightly in size, appearance, and habitat preference.
Short-beaked common dolphins in the United States are not endangered or threatened. Like all marine mammals, they are protected under the Marine Mammal Protection Act.
Population Status
NOAA Fisheries estimates population size for each stock of short-beaked common dolphin in its stock assessment reports. Overall, this species is still abundant worldwide, except for a few specific populations. There are insufficient data for this species to determine population trends.
Protected Status
CITES Appendix II
MMPA Protected
Appearance
Short-beaked common dolphins are small, measuring less than 6 feet long and weighing about 170 pounds. As adults, males are slightly larger than females. They have a rounded forehead (known as a melon), a moderately long rostrum, and 40 to 57 pairs of small, sharp teeth in each jaw. Their body is sleek with a relatively tall, triangular dorsal fin in the middle of their back.
Short-beaked common dolphins can be identified by their distinctive color pattern, which is often referred to as an “hourglass pattern.” A dark gray cape extends along the back from the head to just below the dorsal fin where a "V" is visible on either side of the body, creating an hourglass image. Forward of the dorsal fin, behind the head, is a yellow/tan panel that contrasts with the dark cape on their back. The side of the body behind the dorsal fin is light gray, and a narrow, dark stripe extends from the lower jaw to the flipper, that includes a complex facial color pattern. The eye is not typically within the stripe, but still stands out due to a patch of dark pigment around the eye.
The color patterns of young and juvenile short-beaked common dolphins are somewhat more muted and paler than older, adult dolphins. Considerable variation in color patterns are evident within populations but more markedly different coloration patterns are evident in other geographic areas.
Behavior and Diet
Short-beaked common dolphins are usually found in large social groups averaging hundreds of individuals and are occasionally seen in larger groups—known as mega-pods—consisting of thousands of animals (up to 10,000 individuals). These large groups are thought to consist of sub-groups of 20 to 30 individuals that are possibly related or separated by age and/or sex.
Short-beaked common dolphins are often active at the surface. These highly social, energetic dolphins commonly leap out of the water at high speeds, flip end-over-end, and somersault in the air. They will also swim alongside ships riding the bow for long periods of time. This “bow riding” behavior has even been observed alongside large whales.
Short-beaked common dolphins usually rest during the day and feed at night. They can dive to approximately 1,000 feet but typically dive to about 100 feet to feed on schooling fish and cephalopods (e.g., squid) that migrate towards the surface at night. Short-beaked common dolphins associate with schools of tuna and seabird-feeding flocks, especially in the eastern tropical Pacific Ocean. They have also been observed in mixed groups with spinner dolphins and striped dolphins.
Where They Live
Short-beaked common dolphins prefer warm tropical to cool temperate waters that are primarily offshore. They can be found along the continental slope in waters between 650 to 6,500 feet deep. In the western North Atlantic, they are often associated with the Gulf Stream current. Short-beaked common dolphins also prefer waters altered by underwater geologic features such as underwater ridges and seamounts where upwelling occurs, increasing nutrient concentrations and supporting higher productivity. The abundance and distribution of short-beaked common dolphins vary based on interannual changes, oceanographic conditions, and seasons. They can be found on the continental shelf or farther offshore. On the U.S. west coast, these dolphins are primarily associated with the California Current and are abundant off California year-round from nearshore to about 300 miles offshore. On the U.S. east coast, they are more common north of Cape Hatteras, North Carolina; however, from summer through autumn, large aggregations of short-beaked common dolphins can be found near Georges Bank (extending from Cape Cod, Massachusetts, to Nova Scotia, Canada), Newfoundland, and the Scotian Shelf. Other distinct populations can be found off of northern Europe, Newfoundland, Africa, Japan, southern Australia, and New Zealand, and in the Black Sea, the Mediterranean Sea, and the southwestern Pacific.
Lifespan & Reproduction
Short-beaked common dolphins have an estimated lifespan of up to 35 years. On average, males become sexually mature at 10 years and females at 8 years, although individuals may become sexually mature between 5 and 12 years. Off the California coast, calving takes place during the winter months after a 10- to 11-month gestation period, whereas calving takes place year-round in the eastern tropical Pacific Ocean. Every 2 to 3 years, adult females give birth to a single calf that is about 2.5 to 3 feet long. Calves begin to wean after about 1 year, but remain dependent on their mother for another year or more.
Threats
Entanglement in Fishing Gear
One of the main threats to short-beaked common dolphins is getting caught in fishing gear. They can become entangled or captured in commercial fishing gear such as gillnets, seines, trawls, trap pots, and longlines. Many fisheries in the Atlantic Ocean capture short-beaked common dolphins as bycatch, and they have the highest mortality rate of all cetaceans affected by the drift gillnet fishery operating off the coast of California.
Hunting
Russia, Japan, and nations bordering the Black Sea and the Mediterranean Sea, hunt short-beaked common dolphins for their meat and oil.
Scientific Classification
| Animalia |
Chordata |
Mammalia |
Cetacea |
Delphinidae |
Delphinus |
delphis |
