
Pygmy Killer Whale
Feresa attenuata

Protected Status
Quick Facts

About The Species
Despite its common name, the pygmy killer whale is a small member of the oceanic dolphin family. They are often confused with false killer whales and melon-headed whales. This species is found primarily in deep waters throughout tropical and subtropical areas of the world. Until a live animal was discovered in 1954, pygmy killer whales were known only from two fossil skulls for over a century. Not much is known about them, and they are considered naturally rare.
Although they face threats from entanglement in fishing gear, pygmy killer whales in the United States are not endangered or threatened. Like all marine mammals, they are protected under the Marine Mammal Protection Act.
Status
NOAA Fisheries estimates population size for each stock of pygmy killer whale in its stock assessment reports. A stock is a group of animals that occupy the same area and interbreed. There are three recognized stocks in the United States: Hawaii, northern Gulf of Mexico, and western North Atlantic.
Protected Status
CITES Appendix II
- Throughout Its Range
MMPA Protected
- Throughout Its Range
Appearance
Pygmy killer whales can reach a length of 8.5 feet and weigh up to 496 pounds. They are about 2.6 feet long as newborns and reach adulthood at 6.5 feet. They have a small head with a rounded melon (or forehead) that extends in front of the mouth, and they have no discernable beak. Their dorsal fin is relatively large and tall and is located behind the mid-back. They have relatively long, pointed, tapering flippers (pectoral fins), and their body is dark gray to black with some small white areas on the lips and belly. They have a fairly prominent, narrow cape that dips only slightly below the dorsal fin and a light gray ventral band.
Pygmy killer whales are easily confused with melon-headed whales because of their similar appearance. The best ways to distinguish between the two species are the pygmy killer whale’s frequent paired white tooth rakes, and the clear demarcation between the pygmy killer whale’s darker cape and lighter lateral pigmentation.
Behavior and Diet
Pygmy killer whales usually occur in groups of 12 to 50 individuals but have been seen in groups up to several hundred individuals. Both sexes may remain in their birth groups throughout their lives. They are generally less active than other oceanic dolphins and are frequently seen "logging"—resting in groups at the surface with all animals oriented the same way.
Pygmy killer whales are very aggressive when kept in captivity. They feed primarily on squids and fishes.
Where They Live
Pygmy killer whales prefer deeper areas of warmer tropical and subtropical waters where their prey is concentrated. They have a circumglobal range from 40 degrees North to 35 degrees South. They may occasionally occur relatively close to shore around oceanic islands. In the United States, they can be found in Hawaii, the northern Gulf of Mexico, and the western North Atlantic. In Hawaii, there are resident populations off Oahu, Penguin Bank, and Hawaii Island.
Lifespan & Reproduction
Reproductive biology is poorly known in this species. Its estimated lifespan is unknown.
Threats
Entanglement in Fishing Gear
Pygmy killer whales can become entangled or captured in commercial fishing gear, such as gillnets, though there is no reported bycatch from U.S. fisheries.
Ocean Noise
Underwater noise pollution can interrupt the normal behavior of pygmy killer whales, which rely on sound to communicate. As ocean noise increases from human sources, communication space decreases—the whales cannot hear each other, or discern other signals in their environment as they do in an undisturbed ocean.
Sound can disturb important activities, such as feeding, migrating, and socializing. Scientific research has documented that ocean noise also causes marine mammals to change the frequency or amplitude of their calls, decrease foraging behavior, become displaced from preferred habitat, or increase the level of stress hormones in their bodies. If loud enough, noise can cause permanent or temporary hearing loss.
Scientific Classification
Kingdom | Animalia | Phylum | Chordata | Class | Mammalia | Order | Cetacea | Family | Delphinidae | Genus | Feresa | Species | attenuata |
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What We Do
Conservation & Management
All pygmy killer whales are protected under the MMPA. Our work protects this species by:
- Reducing interactions with commercial and recreational fishing gear.
- Implementing requirements to reduce serious injuries and mortalities.
- Minimizing the effects of vessel disturbance, noise, and other types of human impacts.
- Educating the public about the threats they face.
Science
Our research projects have helped us better understand pygmy killer whales and the challenges they face. Our work includes:
- Stock assessments.
- Shipboard surveys.
- Aerial surveys.
- Acoustic monitoring.
How You Can Help

Report Marine Life in Distress
Report a sick, injured, entangled, stranded, or dead animal to make sure professional responders and scientists know about it and can take appropriate action. Numerous organizations around the country are trained and ready to respond. Never approach or try to save an injured or entangled animal yourself—it can be dangerous to both the animal and you.
Learn who you should contact when you encounter a stranded or injured marine animal >

Keep Your Distance
Be responsible when viewing marine life in the wild. Observe all small whales from a safe distance of at least 100 yards and limit your time spent observing to 30 minutes or less.

Report a Violation
Call the NOAA Fisheries Enforcement Hotline at (800) 853-1964 to report a federal marine resource violation. This hotline is available 24 hours a day, 7 days a week for anyone in the United States.
You may also contact your closest NOAA Office of Law Enforcement field during regular business hours.
Related Species
In the Spotlight
Management Overview
Like all marine mammals, the pygmy killer whale is protected under the Marine Mammal Protection Act. NOAA Fisheries is working to conserve this species to ensure populations remain stable.
Conservation Efforts
Reducing Interactions with Fishing Gear
Pygmy killer whales can be entangled or caught as bycatch in fishing gear, such as gillnets. NOAA Fisheries is committed to minimizing bycatch in U.S. fisheries to ensure they remain sustainable and to protect species such as the pygmy killer whale.
Learn more about bycatch and fisheries interactions
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings. When stranded animals are found alive, NOAA Fisheries and its partners assess the animal’s health and try to return it to the water. 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 identify strandings due 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 can have implications for human health and welfare.
Learn more about the Marine Mammal Health and Stranding Response Program
Marine Mammal Unusual Mortality Events
Under the Marine Mammal Protection Act, an unusual mortality event (UME) 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.
Get information on active and past UMEs
Get an overview of marine mammal UMEs
Addressing Ocean Noise
Increasing evidence suggests that exposure to intense underwater sound in some settings may cause some cetaceans 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 behavior and hearing. In 2016, we issued technical guidance for assessing the effects of anthropogenic sound on marine mammal hearing.
Regulatory History
Pygmy killer whales are protected under the MMPA.
Key Actions and Documents
Incidental Take Authorization: Scripps Institute of Oceanography Low-Energy Geophysical Survey in the South Atlantic Ocean
Incidental Take Authorization: U.S. Navy Mariana Islands Training and Testing (MITT)
- Letter of Authorization (pdf, 33 pages)
- Revised LOA Application (pdf, 325 pages)
- LOA Application (pdf, 318 pages)
- Monitoring and Reporting
- Notification and Reporting Plan (pdf, 4 pages)
- Biological Opinion
- Environmental Impact Statement
- Public Comments
- NRDC Comment Letter (pdf, 37 pages)
- References (pdf, 25 pages)
Incidental Take Authorization: U.S. Navy Hawaii-Southern California Training and Testing (HSTT) (2018-2025)
- Final Rule for 2 Year Extension
- Proposed Rule for 2 Year Extension
- Notice of Receipt of Application for 2 Year Extension
- Final Rule
- Proposed Rule
- Notice of Receipt of Application for LOA
- LOA for Testing (pdf, 38 pages)
- LOA for Training (pdf, 38 pages)
- Application for Extension (pdf, 84 pages)
- LOA and Rule Application (pdf, 580 pages)
- Monitoring Reports (External Link)
- Environmental Impact Statement (External Link)
- Mitigation Addendum (pdf, 12 pages)
- Notification and Reporting Plan (pdf, 4 pages)
- Final Biological Opinion (pdf, 683 pages)
- Public Comments (External Link)
- References (pdf, 15 pages)
Incidental Take Authorization: Lamont-Doherty Earth Observatory Marine Geophysical Survey in the North Pacific Ocean
More Information
Science Overview
NOAA Fisheries conducts a variety of research on the biology, behavior, and ecology of pygmy killer whales. The results of this research are used to inform management decisions and enhance protection efforts for this species.
Population/Stock Assessments
Determining the size of pygmy killer whale populations helps resource managers gauge the success of NOAA Fisheries’ conservation measures. Our scientists collect and present these data in annual stock assessment reports.
Shipboard Studies
NOAA Fisheries conducts research cruises to collect information on pygmy killer whale stocks, such as habit preferences and feeding ecology. For example, the NOAA Pacific Islands Fisheries Science Center conducted a Hawaiian Islands Cetacean and Ecosystem Assessment Survey in 2017 and recorded sightings of pygmy killer whales and other cetaceans in the area. These studies help us estimate the abundance of these animals and can be used in management actions to protect them.
Acoustic Science
Our research also focuses on acoustics—the physics of the properties of sound. We study the basic acoustic behavior of cetaceans and fish, mapping the acoustic environment and finding better ways to find cetaceans using acoustic technologies. Our acoustic research also assesses the degree to which human-caused activities are changing the underwater soundscape, how these changes may potentially impact marine animals, and what measures can be taken to mitigate these potential impacts.