Long-Beaked Common Dolphin
About the Species
Long-beaked common dolphins can be found in large social groups in the Atlantic, Indian, and Pacific Oceans. This highly social and energetic species prefers shallow, tropical, subtropical, and warmer temperate waters closer to the coast and on the continental shelf.
Long-beaked common dolphins are closely related to—and easily confused with—short-beaked common dolphins. Once thought to be a single species, the two species differ slightly in size, appearance and habitat preference. Long-beaked common dolphins are less abundant than their short-beaked relatives.
The eastern North Pacific long-beaked common dolphin, the only population found in the United States, is not listed as threatened or endangered. Like all marine mammals, they are protected under the Marine Mammal Protection Act.
NOAA Fisheries reviews the status of the eastern North Pacific long-beaked common dolphin in its stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. Although they are less abundant than short-beaked common dolphins, long-beaked common dolphins are not considered threatened or endangered.
Long-beaked common dolphins are small, measuring 6 to 8.5 feet long and weighing between 160 and 500 pounds. Males are around five percent larger than females. They have a recognizable dolphin shape with a rounded forehead (known as a melon), a moderately long rostrum, and 47 to 67 pairs of small sharp teeth in each jaw, more than any other dolphin species. Their bodies are sleek and have a relatively tall, triangular dorsal fin in the middle of the back.
Long-beaked common dolphins can be identified by their distinctive color pattern. They have an hourglass pattern created by a dark back, a dull yellow/tan panel on the side in front of the dorsal fin and a lighter gray panel extending along the side from the dorsal fin to their tail stock. A broad dark stripe extends from the lower jaw to the flipper and the dark cape on their back typically includes the eye.
The color patterns of young and juvenile long-beaked common dolphins are generally more muted than in adults. The color patterns can be distinct and vary by geographic and regional areas. Distinguishing the species of common dolphins is most difficult for young dolphins.
Behavior and Diet
Long-beaked common dolphins are usually found in large social groups averaging from 100 to 500 animals, and they are occasionally seen in larger herds of thousands of individuals. These large schools are thought to consist of smaller sub-groups of ten to 30 potentially related individuals or individuals of similar age and sex.
Long-beaked common dolphins are often active at the surface and display various behaviors. These highly social, energetic dolphins are commonly seen swimming rapidly and leaping out of the water at high speeds. They will also swim near the front of ships and ride the pressure waves (or bow-riding) for long periods of time.
Long-beaked common dolphins feed in relatively shallow waters on small schooling fish (e.g., anchovies, hake, pilchards, and sardines), krill, and cephalopods (e.g., squid). Dolphin groups may work together to herd schools of prey. Their diving behavior is thought to be like that of short-beaked common dolphins.
Where They Live
Long-beaked common dolphins generally prefer shallow, tropical, subtropical, and warmer temperate waters within 50 to 100 nautical miles of the coast and on the continental shelf, often in inshore waters. There are discrete populations with limited distribution along coastlines in the Atlantic, Indian, and Pacific Oceans. In U.S. waters, this species is only found along the west coast, and their distribution extends from Baja California, Mexico, northward to central California. Other, discrete populations can be found off the coasts of South America (Peru, Chile, Venezuela, Brazil, and Argentina), West Africa, South Africa, Madagascar, the Arabian Peninsula, India, Indonesia, China, Korea, and southern Japan. The distribution and population center of this species may change with varying oceanographic conditions.
Lifespan & Reproduction
Long-beaked common dolphins have an estimated lifespan of approximately 40 years and become sexually mature at about ten years at around 6.5 feet in length. Breeding usually takes place between the spring and autumn. Calving takes place primarily in spring after a 10- to 11-month gestation period. Every one to three years, females give birth to a single calf that is about 2.5 to 3 feet long and weighs about 20 pounds.
One of the main threats to long-beaked common dolphins is entanglement in fishing gear (e.g., driftnets, gillnets, purse seines, and trawls). They can become entangled or captured in commercial fishing gear, such as gillnets, seines, trawls, trap pots, and longlines.
Small numbers of long-beaked common dolphins have been killed for food and bait in the Caribbean, Venezuela, Peru, West Africa, and other offshore islands. They have been taken in the Japanese drive fisheries as well.
Long-beaked common dolphins are particularly susceptible to domoic acid poisoning, which is a neuro-toxin produced by algae. When harmful algal blooms (HABs) occur, sardines and anchovies eat the harmful algae, and they are eaten by long-beaked common dolphins. This bioaccumulation of toxic algae can cause seizures and sometimes death in these dolphins and other marine mammals who consume affected prey.
In the Spotlight
Like all marine mammals, the long-beaked common dolphin is protected under the Marine Mammal Protection Act. NOAA Fisheries is working to conserve this species to ensure populations remain stable.
Reducing Interactions with Fishing Gear
Long-beaked common dolphins are caught as bycatch in fishing gear, leading to deaths and serious injuries. In 1997, NOAA Fisheries implemented the Pacific Offshore Cetacean Take Reduction Plan, which requires the use of pingers (an acoustic deterrence device) and 6-fathom net extenders in the California/Oregon drift gillnet fishery to reduce bycatch of cetaceans, including long-beaked common dolphins. The Pacific Offshore Cetacean Take Reduction Team continues to meet and recommend measures to further reduce bycatch and achieve MMPA goals.
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings including all dolphins and porpoises. 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
Long-beaked common dolphins have never been part of a declared unusual mortality event. 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.
Minimizing Harassment and Illegal Feeding
As human interactions with wild dolphins increase, so does the risk of disturbing or injuring these animals. NOAA Fisheries provides guidance on how to safely and responsibly view dolphins, including the following initiatives:
Key Actions and Documents
Estimating the size of long-beaked common dolphin populations and the number of dolphins killed in fisheries helps resource managers determine 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 dolphins’ distribution, reproduction, and habitat preferences. For example, in 2009, NOAA’s Southwest Fisheries Science Center conducted a research cruise (PDF, 60 pages) to help estimate the abundance of both long-beaked and short-beaked common dolphins off southern California in the United States and Baja California in Mexico. For both species, NOAA collected data to estimate abundance, pregnancy and birth rates, calving season, gene flow, and contaminant concentrations. NOAA also characterized the habitat and ecosystem in which these dolphins live. NOAA Fisheries can use information from this research to improve conservation and management plans for these species.