Transient Orcas of the pacific northwest
Killer whales, (Orcinus orca) commonly called orcas, are found in all the world’s oceans, but the best known and most studied populations are those of the Pacific Northwest.
Fast Facts:
Length Adult Male : 32 feet (9.6 m)
Adult Female : 23 feet (8.2 m)
Birth Length :6-7 feet (1.8-2.1 m)
Weight Adult Male : 9 tons
Adult Female : 4 tons
Birth Weight : 400lbs (181 kg)
Life Expectancy Average 70 years (in the wild)
Length Adult Male : 32 feet (9.6 m)
Adult Female : 23 feet (8.2 m)
Birth Length :6-7 feet (1.8-2.1 m)
Weight Adult Male : 9 tons
Adult Female : 4 tons
Birth Weight : 400lbs (181 kg)
Life Expectancy Average 70 years (in the wild)
Various orca populations:
All orcas are top predators, with complex social structures. Individual orca populations have become specialized to feed on particular prey species. There are three orca populations in the Pacific Northwest:
Resident Orcas:
Resident orcas of the pacific northwest feed primarily on fish, they prefer salmon in particular. They live in pods, which are tightly bound family units, and they return to the same feeding grounds each year.
Transient Orcas:
Transient orcas feed on other marine mammals, and travel in smaller family groups. They live further offshore and travel much more than resident orcas.
Offshore Orcas:
Not much is known about offshore orcas, as they live very far from shore. They also hunt marine mammals, and live in the open ocean.
All orcas are top predators, with complex social structures. Individual orca populations have become specialized to feed on particular prey species. There are three orca populations in the Pacific Northwest:
Resident Orcas:
Resident orcas of the pacific northwest feed primarily on fish, they prefer salmon in particular. They live in pods, which are tightly bound family units, and they return to the same feeding grounds each year.
Transient Orcas:
Transient orcas feed on other marine mammals, and travel in smaller family groups. They live further offshore and travel much more than resident orcas.
Offshore Orcas:
Not much is known about offshore orcas, as they live very far from shore. They also hunt marine mammals, and live in the open ocean.
Biology:
Camouflage: The Orca is counter shaded: black on the top and mostly white on the bottom. Looking down from above, the black on the dorsal side mixes with the dark ocean. Looking up from below, the white on the ventral side blends into the sunlit water. This makes it difficult for other animals to recognize that it is a killer whale, until its too late. Dorsal fins (Dorsal fluke): Male Orcas have the largest dorsal fin of any marine mammal. It can get up to 6 feet tall. On females it’s a bit shorter and more curved. The dorsal fin acts like a keel, and each dorsal fin is unique for each Orca. The dorsal fins are not made of bone or cartilage; instead they are made of dense connective tissue. Senses: The eye is located just below and in front of the eyepatch. Orcas have excellent eyesight in and out of the water. They also have a well-developed sense of hearing. And like other cetaceans, Orcas receive sound through receptors in their jawbones. The jawbone acts like a conduit, transmitting the sounds to the ear canal and auditory nerves. Echolocation: They create high frequency sound waves that are passed through the melon. The melon focuses these sounds and projects them into the water. The sound bounces off the objects and returns in the form of an echo. Blowhole: Cetaceans are conscious breathers. They have to remember to take a breath every time they need air. Orcas breathe by opening the muscular flap of the blowhole. When closed, the blowhole is completely airtight. Reproduction: Females can begin to bear calves in their early teens, and can continue to do so into their 50's. It is assumed that mating occurs year-round because calves are born throughout the year (unlike California sea lions, which are born in June—with more than half of them born on June 15). Gestation: The gestation period for orcas is 14 months. The calves are about 3 feet long at birth, and are assisted to the surface by other orcas. They nurse for about one year. |
|
Social Structure and Behavior:
Orcas are highly social animals that travel in groups called pods. Pods usually consist of 5 - 30 whales, although some pods may combine to form a group of 100 or more. Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Unlike in resident pods, extended or permanent separation of transient offspring is common. Some males roam around, joining groups that contain reproductive females.
Orcas establish social hierarchies, and pods are lead by females. Resident killer whales in the eastern North Pacific have a particularly complex and stable social grouping system. Unlike any other mammal species whose social structure is known, residents live with their mothers for their entire lives. Due to orcas' complex social bonds and society, many marine experts have concerns about how humane it is to keep these animals in captive situations. These animals are thought to have a complex form of communication with different dialects (slightly different language) from one pod to another.
Threats and Conservation:
About 320 individually identified transient orcas are commonly seen along the coastline of Washington and British Columbia and from Southeast Alaska to California. Gulf of Alaska transients also number just over 300, and a third clan was all but wiped out by the 1989 Exxon Valdez oil spill. Fewer than ten survivors remain in 2009, none of which are reproductive females.
In the 1960s and 70s, the resident orcas of the Pacific Northwest were heavily hunted for display in marine parks and aquariums. Over one-third of entire population was removed, including most of the calves and the breeding mothers. The southern resident orca population is now listed as Endangered, and the the long-term impact of the captures is cited as a factor in their decline. Other factors include prey abundance (lack of chinook salmon), toxin accumulations, and noise and stress from vessel impacts. If the current trends continue or worsen, the southern residents could go extinct in as few as 100 years. In Southeast Alaska, the AT1 pod of transient orcas was heavily impacted by the 1989 Exxon Valdez oil spill in Prince William Sound. Since then, their numbers have plummeted from 22 individuals to 7. They were designated as Endangered by NOAA Fisheries, and their long-term chances of survival are slim. Global warming and its impact on ocean conditions is a deepening concern for orcas and other marine species.
Because orcas are known as the top predator of the ocean, it's very easy for pollutants to become concentrated and reach dangerous levels their bodies since these pollutants make their way through the marine food chain. For example, In the Pacific Northwest, the marine food chain is consisted of zoo plankton feeding on phytoplankton, krill feeding on zoo plankton, salmon feeding on krill, and orcas feeding on the salmon (resident orcas), which has become endangered because of pollution, over-fishing, and habitat loss. In the case of transient orcas, dolphins, seals and sea lions feed on the salmon, while the mammal-eating transients feed on the very same marine mammals that feed on the salmon. This means that prey animals that contain toxins in their bodies pass them on to animals that are higher on the food chain and because of this, orcas have been shown to have high and dangerous levels of concentrated pollutants in their bodies.
Transient orcas, which specialize in feeding marine mammals, are more contaminated than resident orcas due to dietary differences. Their bodies are so full on toxins that when they are found dead on beaches, their remains are often treated as toxic hazardous waste when necropsies (autopsies for non-humans) are performed on them.
More info on contaminants in orcas can be found here: http://www.ptmsc.org/orca_contamination.html
Want to help? See below for a handbook from the Defenders of Wildlife.
Did you know?
Orcas have the second-heaviest brains among marine mammals (after Sperm Whales, which have the largest brain of any animal).
Orcas are notable for their complex societies. Only elephants and higher primates, such as humans, live in comparably complex social structures.
Orcas are pink and black when they are born!
Orcas are mammals that use echo location (from their heads!) to locate their prey.
Orcas, or killer whales, are not whales at all, they are actually dolphins.
Orcas are one of the fastest creatures in the sea, traveling up to 30 miles per hour.
Orcas are able to control the flow of blood to their hearts and brains, which keeps them from suffering from a lack of oxygen when they are deep underwater.
Orcas have an anatomy with the amazing capability to withstand very cold sea temperatures and also to be part of tropical ecosystems.
Orcas are not limited by salinity, temperature or depth of the sea, making them able to stay in deep waters and very close to the coast, where there are only a few meters of depth.
Learn more:
Books:
Killer Whales: The Natural History and Genealogy of Orcinus Orca in British Columbia and Washington State (Updated Edition) by John K. B. Ford et al, 2000
Orca: The Whale Called Killer by Erich Hoyt, 1990
See More Readers: Killer Whales -Level 1 by Seymour Simon, 2002
Movie:
Blackfish
Links:
http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/killerwhale.htm
Orcas are highly social animals that travel in groups called pods. Pods usually consist of 5 - 30 whales, although some pods may combine to form a group of 100 or more. Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Unlike in resident pods, extended or permanent separation of transient offspring is common. Some males roam around, joining groups that contain reproductive females.
Orcas establish social hierarchies, and pods are lead by females. Resident killer whales in the eastern North Pacific have a particularly complex and stable social grouping system. Unlike any other mammal species whose social structure is known, residents live with their mothers for their entire lives. Due to orcas' complex social bonds and society, many marine experts have concerns about how humane it is to keep these animals in captive situations. These animals are thought to have a complex form of communication with different dialects (slightly different language) from one pod to another.
Threats and Conservation:
About 320 individually identified transient orcas are commonly seen along the coastline of Washington and British Columbia and from Southeast Alaska to California. Gulf of Alaska transients also number just over 300, and a third clan was all but wiped out by the 1989 Exxon Valdez oil spill. Fewer than ten survivors remain in 2009, none of which are reproductive females.
Because orcas are known as the top predator of the ocean, it's very easy for pollutants to become concentrated and reach dangerous levels their bodies since these pollutants make their way through the marine food chain. For example, In the Pacific Northwest, the marine food chain is consisted of zoo plankton feeding on phytoplankton, krill feeding on zoo plankton, salmon feeding on krill, and orcas feeding on the salmon (resident orcas), which has become endangered because of pollution, over-fishing, and habitat loss. In the case of transient orcas, dolphins, seals and sea lions feed on the salmon, while the mammal-eating transients feed on the very same marine mammals that feed on the salmon. This means that prey animals that contain toxins in their bodies pass them on to animals that are higher on the food chain and because of this, orcas have been shown to have high and dangerous levels of concentrated pollutants in their bodies.
Transient orcas, which specialize in feeding marine mammals, are more contaminated than resident orcas due to dietary differences. Their bodies are so full on toxins that when they are found dead on beaches, their remains are often treated as toxic hazardous waste when necropsies (autopsies for non-humans) are performed on them.
More info on contaminants in orcas can be found here: http://www.ptmsc.org/orca_contamination.html
Want to help? See below for a handbook from the Defenders of Wildlife.
Did you know?
Orcas have the second-heaviest brains among marine mammals (after Sperm Whales, which have the largest brain of any animal).
Orcas are notable for their complex societies. Only elephants and higher primates, such as humans, live in comparably complex social structures.
Orcas are pink and black when they are born!
Orcas are mammals that use echo location (from their heads!) to locate their prey.
Orcas, or killer whales, are not whales at all, they are actually dolphins.
Orcas are one of the fastest creatures in the sea, traveling up to 30 miles per hour.
Orcas are able to control the flow of blood to their hearts and brains, which keeps them from suffering from a lack of oxygen when they are deep underwater.
Orcas have an anatomy with the amazing capability to withstand very cold sea temperatures and also to be part of tropical ecosystems.
Orcas are not limited by salinity, temperature or depth of the sea, making them able to stay in deep waters and very close to the coast, where there are only a few meters of depth.
Learn more:
Books:
Killer Whales: The Natural History and Genealogy of Orcinus Orca in British Columbia and Washington State (Updated Edition) by John K. B. Ford et al, 2000
Orca: The Whale Called Killer by Erich Hoyt, 1990
See More Readers: Killer Whales -Level 1 by Seymour Simon, 2002
Movie:
Blackfish
Links:
http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/killerwhale.htm
citizen-advocate-handbook-2012.pdf | |
File Size: | 1957 kb |
File Type: |