About The Species

The killer whale, also known as orca, is one of the top marine predators. It is the largest member of the Delphinidae family, or oceanic dolphins. Members of this family include all dolphin species, as well as other larger species such as the long-finned pilot whales and short-finned pilot whales, whose common names also contain "whale" instead of "dolphin." Found in every ocean in the world, they are the most widely distributed of all cetaceans (whales and dolphins). Scientific studies have revealed many different populations with several distinct ecotypes (or forms) of killer whales worldwide—some of which may be different species or subspecies. They are one of the most recognizable marine mammals, with their distinctive black and white bodies. Globally, killer whales occur in a wide range of habitats, both open seas and coastal waters.Taken as a whole, the species has the most varied diet of all cetaceans, but different populations are usually specialized in their foraging behavior and diet. They often use a coordinated hunting strategy, working as a team like a pack of wolves. Hunters and fishermen once targeted killer whales. As a result, historical threats to killer whales included commercial hunting, and culling to protect fisheries from killer whales. In addition, although live capture of killer whales for aquarium display and marine parks no longer occurs in the United States, it continues to remain a threat globally. Today, some killer whale populations face many other threats, including food limitations, chemical contaminants, and disturbances from vessel traffic and sound. Efforts to establish critical habitat, set protective regulations, and restore prey stocks are essential to conservation, especially for endangered killer whale populations. All killer whale populations are protected under the Marine Mammal Protection Act. Only two populations receive special protections under federal law: Southern Resident population (listed as endangered under the Endangered Species Act).

AT1 Transient population (listed as depleted under the MMPA). Southern Resident killer whales are the only endangered population of killer whales in the United States, ranging from central California to southeast Alaska. Long-term commitments across state and national borders are needed to stabilize the Southern Residents’ population and prevent their extinction. The Southern Resident killer whale is one of NOAA Fisheries' Species in the Spotlight. This initiative includes animals considered most at risk for extinction and prioritizes recovery efforts. NOAA Fisheries is committed to the conservation of killer whales and the protection and recovery of endangered populations. Our scientists and partners use a variety of innovative techniques to study and protect them. We also work with our partners to develop regulations and management plans that protect killer whales and their food sources, decrease contaminants in oceans, reduce ocean noise, and raise awareness about the whales and the actions people can take to support their recovery.

Status

Several different populations and ecotypes of killer whales are found throughout the world. NOAA Fisheries estimates population size in our stock assessment reports. It is estimated that there are around 50,000 killer whales globally. Approximately 2,500 killer whales live in the eastern North Pacific Ocean—home to the most well-studied killer whale populations.

In recent decades, several populations of killer whales have declined and some have become endangered. The population of AT1 Transients, a subgroup of Transient killer whales in the eastern North Pacific, has been reduced from 22 to 7 whales since the 1989 Exxon Valdez oil spill. In 2004, NOAA Fisheries designated this group as depleted under the MMPA based on the results of the status review (PDF, 25 pages).

Scientists estimate the minimum historical population size of Southern Residents in the eastern North Pacific was about 140 animals. Following a live-capture fishery in the 1960s for use in marine mammal parks, 71 animals remained in 1974. Although there was some growth in the population in the 1970s and 1980s, with a peak of 98 animals in 1995, the population experienced a decline of almost 20 percent in the late 1990s, leaving 80 whales in 2001. The population census at the end of 2016 counted only 78 whales, and several deaths in 2017 brought the total of this struggling population to 76. In 2003, NOAA Fisheries began a research and conservation program with congressional funding to address the dwindling population. Southern Residents were listed as endangered in 2005 under the ESA and a recovery plan (PDF, 251 pages) was completed in 2008.

Learn more about the different populations and social organization of killer whales

Protected Status

ESA Endangered 1 distinct population segment Southern Resident DPS

CITES Appendix II Throughout Its Range

MMPA Protected Throughout Its Range

MMPA Depleted 1 stock AT1 Transient stock

Appearance

Killer whales are mostly black on top with white undersides and white patches near the eyes. They also have a gray or white saddle patch behind the dorsal fin. These markings vary widely between individuals and populations. Adult males develop disproportionately larger pectoral flippers, dorsal fins, tail flukes, and girths than females. Learn more about the physical features of various populations of killer whales (PDF, 1 page)

Behavior and Diet

Killer whales are highly social, and most live in social groups called pods (groups of related individuals seen together more than half the time). Individual whales tend to stay in their original pods. Pods typically consist of a few to 20 or more animals, and larger groups sometimes form for temporary social interactions, mating, or seasonal concentrations of prey. Killer whales rely on underwater sound to feed, communicate, and navigate. Pod members communicate with each other through clicks, whistles, and pulsed calls. Each pod in the eastern North Pacific possesses a unique set of calls that are learned and culturally transmitted among individuals. These calls maintain group cohesion and serve as family badges. Although the diet of killer whales depends to some extent on what is available where they live, it is primarily determined by the culture (i.e., learned hunting tactics) for each ecotype of killer whale. For example, one ecotype of killer whales in the U.S. Pacific Northwest (called Residents) exclusively eats fish, mainly salmon, and another ecotype in the same area (Transients, or Bigg’s killer whales) primarily eats marine mammals and squid. Killer whales often use a coordinated hunting strategy and work as a team to catch prey. They are considered an apex predator, eating at the top of the food chain

Where They Live

Killer whales are found in all oceans. While they are most abundant in colder waters like Antarctica, Norway, and Alaska, they are also found in tropical and subtropical waters. The most well-studied killer whale populations occur in the eastern North Pacific Ocean. Resident killer whales have been seen from California to Russia. Transient killer whales occur throughout the eastern North Pacific, and are often seen in coastal waters. Their habitat sometimes overlaps with Resident and Offshore killer whales. Offshore killer whales have the largest range of any community, and often occur more than 9 miles offshore.

Lifespan & Reproduction

Male killer whales typically live for about 30 years, but can live up to at least 60 years. Females typically live about 50 years, but can live up to at least 90 years. Females reach sexual maturity when they are between 10 and 13 years old. They are typically pregnant for 15 to 18 months and give birth to a single calf. Calves nurse for at least a year. There is no distinct calving season, so birth can take place in any month. The birth rate for killer whales is not well understood. In some populations, birth rate is estimated at every 5 years for an average period of 25 years. Killer whales, beluga whales, narwhals, short-finned pilot whales, false killer whales, sperm whales, and humans are the only known species that go through menopause.

Threats

Lack of Food Overfishing and habitat loss have decreased the amount of prey available to some killer whales. Without enough prey, killer whales might experience decreased reproductive rates and increased mortality rates. This threat is especially important for Southern Resident killer whales because some populations of their preferred prey, Chinook salmon, are also threatened or endangered. Contaminants Contaminants enter ocean waters and sediments from many sources, such as wastewater treatment plants, sewer outfalls, and pesticide application. Once in the environment, these substances move up the food chain and accumulate in top predators. Killer whales accumulate these contaminants in their bodies because of their long lifespan, position at the top of the food chain, and blubber stores. These contaminants can harm killer whales’ immune and reproductive systems. Despite modern pollution controls, chemical contamination through the food chain continues to threaten killer whales. These controls have reduced, but not eliminated, many contaminants in the environment. Additionally, some of these contaminants persist in the marine environment for decades and continue to threaten marine life. Oil Spills The 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, was strongly correlated with the direct loss of individual killer whales. However, oil spills can also have an indirect impact on killer whales by affecting the abundance of prey species. In addition, the bioaccumulation of certain contaminants such as polychlorinated biphenyls (PCBs) in the food web can be seen in apex predators like killer whales—and particularly among the transient population. Disturbance from Vessels and Sound When vessels are present, killer whales hunt less and travel more. Noise interference from vessels, as well as from industrial and military activities, interrupts killer whales’ ability to use sound, which in turn disturbs their feeding, communication, and orientation. Increased vessel noise causes Southern Resident killer whales to call louder, expending more energy in the process.

Scientific Classification