Habitat & Distribution

Killer Whales

Habitat & Distribution

Habitat/Distribution

  1. Killer whales inhabit all oceans of the world. Next to humans, killer whales are the most widely distributed mammal.
  2. Documented sightings of killer whales are indicated in dark blue.

  3. Killer whales are found in the open ocean, but they seem to be most abundant in coastal waters.
  4. In addition to being found in colder water, killer whales also have been seen in warm water areas such as Hawaii, Australia, the Galapagos Islands, the Bahamas, and the Gulf of Mexico. Such sightings are infrequent, but they do demonstrate the killer whales' ability to venture into tropical waters. Even more surprising, killer whales have been seen in fresh water rivers around the world such as the Rhine, the Thames, and the Elbe. One even traveled some 177 km (110 mi.) up the Columbia River to eat fish.
  5. Killer whales are much more abundant in the Arctic, the Antarctic, and areas of cold-water upwelling.
  6. Killer whales are most numerous in the Arctic, Antarctic and areas of cold water upwellings where food is plentiful.

  7. The three forms of Antarctic killer whales have different distributions.
    • "Type A" killer whales are circumpolar and live offshore in ice-free water.
    • "Type B" killer whales inhabit inshore waters of Antarctica and the Antarctic Peninsula, near the pack ice.
    • "Type C" killer whales inhabit inshore waters and pack ice and are most common in the eastern Antarctic.
  8. The resident and transient killer whales of the eastern North Pacific Ocean have overlapping but different distributions.
    • Researchers have identified two distinct communities of resident whales, with different distributions. Whales in both communities tend to stay within about 800 km (500 mi.) of coastline. They tend to follow direct routes when traveling, from headland to headland.
      • The northern resident stock occurs from the top half of British Columbia’s Vancouver Island north through Alaska.
      • The southern resident stock occurs from the lower half of British Columbia’s Vancouver Island south through Washington State.
    • The transient stock occurs from Alaska’s Aleutian Islands to Southern California.

Migration

  1. In some areas, seasonal movements of killer whales are influenced by migration of their prey.
  2. In the Antarctic at least some populations of killer whales appear to make considerable seasonal movements in response to the advance and retreat of pack ice.

Population

  1. The worldwide population of killer whales is unknown. In fact, population numbers and trends are poorly known for many species of ocean animals. Estimating abundance is difficult due to their vast distribution and their aquatic habits.
  2. Although estimating the abundance of marine mammal populations is difficult, a few regional groups of killer whales have been studied rather thoroughly. Experts have estimated killer whale abundance for these regional groups.
    • In the eastern North Pacific, experts have identified 723 whales in the northern resident community, a number that does not include another 241 “unclassified” whales from western Alaska that are presumed to also be resident whales.
    • The Eastern North Pacific southern resident community includes only 89 whales. As of 2005, this community listed as an endangered “distinct population segment” under the Endangered Species Act. The population declined 20% in the 1990s.
    • Experts have catalogued 346 whales in the eastern North Pacific transient stock, a number that does not include another 83 whales that are presumed to be transient whales.
    • The Eastern North Pacific offshore stock occurs from Southeast Alaska through California. Experts have identified 211 offshore killer whales off British Columbia and California, but many more offshore whales have not been photographed. Using line-transect killer whale counts off the coast of California, Oregon, and Washington along with what they know about offshore and transient population percentages, researchers estimate that there are at least 466 offshore whales (probably more) along California, Oregon, and Washington. This number is likely a considerable underestimate of the total population of offshore killer whales.
    • The Hawaiian stock occurs in the U.S. Exclusive Economic Zone surrounding the Hawaiian Islands. A line-transect survey yielded an abundance estimate of 430 killer whales.
    • The best available estimate for the number of killer whales inhabiting the northern Gulf of Mexico is about 133 whales.
    • About 1,900 killer whales inhabit the waters around Japan.
    • Using line transect sampling, researchers calculated that about 80,400 killer whales probably inhabit Antarctic waters south of the Antarctic Convergence during the month of January. (The Antarctic Convergence is a biological “border” that forms where cold Antarctic waters meet warmer waters to the north. Usually somewhere between 49° and 55° south latitude, the Antarctic Convergence varies seasonally.)
  3. With the exception of the southern resident community in the eastern North Pacific, killer whales are not endangered.