Atlantic Spotted Dolphin

About the Species

Atlantic spotted dolphins are found in the tropical waters of the Atlantic Ocean. They usually form groups of five to 50 individuals but sometimes travel in groups of up to 200. They are fast swimmers and often “surf” in the waves created by vessels. 

Young Atlantic spotted dolphins do not have spots. As a result, they can look like slender bottlenose dolphins. Their distinctive spotted pattern starts to appear all over their bodies as they get older. 

Atlantic spotted dolphins, like all marine mammals, are protected under the Marine Mammal Protection Act.

NOAA Fisheries and its partners are working to conserve Atlantic spotted dolphins and further our understanding of this species through research and conservation activities.

Status

NOAA Fisheries estimates population size in our stock assessment reports. 

The worldwide population of Atlantic spotted dolphins is unknown. Scientists estimate that there are at least 81,000 Atlantic spotted dolphins in U.S. waters. 

To manage Atlantic spotted dolphins in U.S. waters, we have divided them into three stocks: the northern Gulf of Mexico stock, the Puerto Rico and U.S. Virgin Islands stock, and the western North Atlantic stock. Based on the most recent surveys, our scientists estimate that there are about 37,000 dolphins in the northern Gulf of Mexico stock and about 44,000 dolphins in the western North Atlantic stock. The number of dolphins in the Puerto Rico and U.S. Virgin Islands stock is unknown. 

Appearance

Atlantic spotted dolphins are about 5 to 7.5 feet long and weigh about 220 to 315 pounds. They have a robust body with a tall, curved dorsal fin located midway down their back. Their beaks are moderately long. Like other cetaceans, their head has a distinctive melon, a rounded forehead that collects sounds from the environment. They have 30 to 42 pairs of small, cone-shaped teeth in each jaw.

Atlantic spotted dolphins’ color patterns vary with age and location. Young dolphins do not have any spots. Instead, they have a dark gray back with a pale white underside. This lack of spots can make young Atlantic spotted dolphins look like slender bottlenose dolphins. An Atlantic spotted dolphin starts to develop spots after its first birthday. As the dolphin matures, the spots become darker and more widespread, especially on its back. 

Behavior and Diet

Atlantic spotted dolphins are usually found in groups of less than 50 individuals but sometimes travel in groups of up to 200. In coastal waters, groups usually consist of five to 15 individuals. Within these groups, the dolphins are sometimes organized by age or sex. Atlantic spotted dolphins blow bubbles through their blowholes as one way to communicate with members of their group. They also communicate with sound. 

Atlantic spotted dolphins are often described as “acrobatic” swimmers, frequently leaping out of the water or jumping at the water’s surface. They can also swim very quickly and often “surf” in the waves created by vessels. They sometimes interact with other cetacean species, such as bottlenose dolphins [link to /species/common-bottlenose-dolphin].

Atlantic spotted dolphins can dive up to 200 feet and have been recorded holding their breath for up to 10 minutes. Most of their dives are less than 30 feet and last for 2 to 6 minutes. These dolphins eat small fish, invertebrates, and cephalopods (such as squid and octopi). They have 30 to 42 pairs of small, cone-shaped teeth in each jaw. Groups of dolphins often coordinate their movements to catch prey together. Individuals sometimes use their beaks to dig into the sand on the ocean bottom to catch hidden fish.

Where They Live

Atlantic spotted dolphins are found in warm temperate, subtropical, and tropical waters throughout the Atlantic Ocean. Their range includes the waters of the U.S. East Coast (Gulf of Mexico to Massachusetts), the Bahamas, Brazil, the Azores and Canary Islands, and Gabon. Warm currents such as the Gulf Stream may affect their distribution.

Atlantic spotted dolphins prefer the waters along the continental shelf (the edge of a continent below the ocean’s surface). They usually live in coastal or continental shelf waters that are 65 to 820 feet deep, but are sometimes found in deeper oceanic waters.

Lifespan & Reproduction

The estimated lifespan of Atlantic spotted dolphins is unknown. They reach sexual maturity when they are 8 to 15 years old. Females give birth to a single calf every 1 to 5 years. Mothers nurse their calves for 1 to 5 years. 

Threats

Entanglement

One of the main threats to Atlantic spotted dolphins is getting caught in fishing gear. Dolphins can become entangled or captured in commercial fishing gear such as gillnets and purse seines. These interactions can cause dolphins to be injured or killed by entanglement in the gear. 

Ocean noise

Underwater noise pollution interrupts the normal behavior of Atlantic spotted dolphins that rely on sound to communicate and echolocate. If loud enough, noise can cause permanent or temporary hearing loss. Noise interference from vessels, as well as industrial and military activities, disturbs Atlantic spotted dolphins’ feeding, communication, and orientation.

Illegal feeding and harassment

Atlantic spotted dolphins sometimes interact with different types of fishing vessels, often following them and eating discarded catch. A few Atlantic spotted dolphins have been hunted and killed in the Caribbean, South America, West Africa, and other offshore islands for food and bait.

Scientific Classification

Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Cetacea
Family	Delphinidae
Genus	Stenella
Species	frontalis