About the Species
Rough-toothed dolphins are found throughout the world in tropical and warmer temperate waters. These small members of the dolphin family usually travel in small, tight-knit groups of two to 20 individuals. Their common name was based on the ridges found on their teeth, which are unique to this species.
Rough-toothed dolphins can remain underwater for up to 15 minutes. They can also adapt well to captivity, which is unusual for oceanic dolphins.
Rough-toothed dolphins, like all marine mammals, are protected under the Marine Mammal Protection Act. NOAA Fisheries and its partners are working to conserve rough-toothed dolphins and further our understanding of this species through research and conservation activities.
NOAA Fisheries estimates population size in its stock assessment reports.
The worldwide population of rough-toothed dolphins is unknown. To manage rough-toothed dolphins in U.S. waters, we have divided them into three stocks:
- Hawaiian stock
- Northern Gulf of Mexico stock
- Western North Atlantic stock
Our scientists estimate that there are about 6,000 dolphins in the Hawaiian stock, 600 dolphins in the northern Gulf of Mexico stock, and 300 dolphins in the western North Atlantic stock—for a total of about 6,900 rough-toothed dolphins in U.S. waters.
CITES Appendix II
- Throughout Its Range
- Throughout Its Range
Rough-toothed dolphins are relatively small compared to other dolphins. They can reach up to 8.5 feet in length and weigh about 350 pounds. They have a small head with a long rostrum and no demarcation between their gently sloping melon (or forehead) and rostrum. Their dorsal fin and pectoral fins or flippers are distinctively large, which is characteristic of this species. They have a “reptilian” appearance that is also distinct and unique among dolphins.
Rough-toothed dolphins have dark gray bodies with a white throat and “lips.” They also have a narrow dark cape that runs down their back between the blowhole and dorsal fin. Their underside usually has some white or lighter spots or blotches.
Behavior and Diet
Rough-toothed dolphins are usually found in tight-knit groups of approximately 10 to 20 individuals. However in Hawaii, they are found in smaller groups of on average three individuals and a median group size of seven; they are rarely observed in larger groups of up to 100 individuals. They often associate with other cetacean species, including short-finned pilot whales, bottlenose dolphins, pantropical spotted dolphins, and spinner dolphins. They eat squid and different types of fish.
Where They Live
Rough-toothed dolphins are found in deep oceanic waters throughout tropical and warmer temperate areas of the world. They are generally found in the Atlantic, Indian, and Pacific Oceans from 40° North to 35° South. The main factor in determining their preferred habitat is the abundance of prey.
Lifespan & Reproduction
Rough-toothed dolphins can live for up to 36 or more years. Sexual maturity occurs at 10 to 14 years of age. Little else is known about their reproductive behavior.
One of the main threats to rough-toothed dolphins is getting entangled or captured in commercial fishing gear, such as gillnets and in drive fisheries outside of the U.S., which can injure or kill them. While there is no reported bycatch from U.S. fisheries, rough-toothed dolphins are known to take bait from fisheries in Hawaiߵi.
Rough-toothed dolphins have been killed in direct fisheries in Japan, Sri Lanka, Indonesia, Papua New Guinea, the Solomon Islands, West Africa, and the Caribbean Sea.
Underwater noise pollution interrupts the normal behavior of rough-toothed dolphins, which rely on sound to communicate and echolocate. If loud enough, noise can cause temporary or permanent hearing loss. Noise interference from vessels, as well as industrial and military activities, disturbs rough-toothed dolphins’ feeding, communication, and orientation.
In the Spotlight
Rough-toothed dolphins, like all marine mammals, are protected under the Marine Mammal Protection Act. In the United States, NOAA Fisheries works to protect all stocks of rough-toothed dolphins.
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
Rough-toothed dolphins 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
Underwater noise threatens rough-toothed dolphin populations, interrupting their normal behavior and driving them away from areas important to their survival. Increasing evidence suggests that exposure to intense underwater sound in some settings may cause some rough-toothed dolphins to strand and ultimately die. NOAA Fisheries is investigating all aspects of acoustic communication and hearing in marine animals, as well as the effects of sound on whale behavior and hearing. In 2016, we issued marine mammal acoustic technical guidance for assessing the effects of anthropogenic (human-caused) sound on marine mammals’ hearing.
Educating the Public
NOAA Fisheries aims to increase public awareness and support for rough-toothed dolphin conservation through education, outreach, and public participation. We share information with the public about the status of rough-toothed dolphins, as well as our research and efforts to promote their recovery.
All marine mammals, including rough-toothed dolphins, are protected in the United States under the Marine Mammal Protection Act.
Key Actions and Documents
NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of rough-toothed dolphins. The results of this research are used to inform management decisions for this species.
Determining the size of rough-toothed dolphin populations helps resource managers determine the success of conservation measures. Our scientists collect population information and present the data in annual stock assessment reports.
Monitoring Population Abundance and Distribution
Scientists observe rough-toothed dolphins to record their numbers and distribution. By comparing numbers collected over multiple years, scientists can look for trends—i.e., whether the population is increasing, decreasing, or remaining stable during a given period.