Humans have observed killer whales for centuries. A killer whale image was found carved into a rock in northern Norway and is estimated to be some 9,000 years old, making it the earliest known depiction of a cetacean.
Some human cultures have long been fascinated by killer whales, but until recently their lives were shrouded in misinformation — in the past, this has led to the persecution of these whales.
A few cultures respected killer whales, yet much of the ancient world did not. During the first century A.D., a Roman scholar named Pliny the Elder wrote that killer whales "cannot be properly depicted or described except as an enormous mass of flesh armed with savage teeth".
In 1835, R. Hamilton wrote that the killer whale "...has the character of being exceedingly voracious and warlike. It devours an immense number of fishes of all sizes...when pressed by hunger, it is said to throw itself on every thing it meets with...".
Many civilization envisioned killer whales as terrifying threats to humans, with a 1973 U.S. Navy diving manual warning that killed whales "…will attack human beings at every opportunity".
Killer whales have never been consistently exploited on a large-scale basis. They have been hunted on a small scale for their meat, hides, blubber, and internal organs (which are processed into fertilizer and used as bait).
Before 1981, nearly 6,000 killer whales were taken by Japanese, Norwegian, and Soviet whalers.
As Arctic ice dissipates in areas due to climate change, native Inuits around eastern Greenland have started to hunt killer whales in greater numbers. In some seasons, up to 35 to 40 have been reportedly killed for their meat and whale skin (called mukluk), which is sold at local markets.
Tribes native to the Pacific Northwest incorporate killer whales into art and myth.
The International Whaling Commision (IWC).
In general, killer whales have never been a primary commercial whaling target.
In 1946, 14 countries signed the International Whaling Convention for the regulation of whaling, forming the International Whaling Commission (IWC). The goal of the IWC is to manage whale stocks as a resource.
The IWC monitors whale populations through scientific advisory groups and coordinates and funds a variety of whale research.
In 1986, the IWC declared a moratorium on commercial whaling. The moratorium — which is still in effect — allows for the possibility of regulatory commercial whaling in the future.
Traditionally the IWC's focus has been on whales that have been harvested in large numbers, such as the baleen whales and the sperm whale. While the IWC does not manage populations of small whales such as dolphins, the IWC Scientific Committee studies various populations of small whales and provides advice on them.
Confrontations with Fishermen
In some areas, killer whales feed in connection with fishing operations, "stealing" fish from the fishermen. They eat fish from commercial longlines in New Zealand, Alaska, and Brazil. In Brazil, observers reported that more than 50% of the daily swordfish catch may be eaten by killer whales, and that occasionally the whales eat the entire catch.
Some fishermen blame the destruction of millions of dollars of equipment and fish loss on killer whales, and on rare occasions some have taken to shooting killer whales. Recently, researchers have attempted to develop non-lethal killer whale deterrents, including acoustic harassment devices, electric currents, sparker devices (emits a flash of light to startle whales), rubber bullets, bubble screens, chemicals such as lithium chloride ether (to induce nausea) and reducing the sounds caused by the fishing operations. None of these deterrents have been very effective.
Fishermen shooting killer whales is believed to be one of the contributing factors to the unusually high mortality experienced by one pod off Prince William Sound — whales known for their habit of taking black cod off long-lines.
Both natural toxins and human-made toxins can harm killer whales.
Chemicals that are used on land enter waterways through runoff and eventually end up in the oceans as pollution.
Industrial pollutants are introduced to the marine environment through mining operations, agriculture, pulp mills, and other coastal industrial development.
Household and garden pesticides can enter waterways through sewers and storm drains.
Some pollutants enter the ocean food chain and become concentrated in the bodies of killer whales and other marine predators.
Some of these pollutants (which may not be harmful in small quantities) are stored in an animal's body tissues after they are ingested. Prey animals that contain such toxins in their bodies pass the toxins on to animals higher in the food chain. Pollutants can become concentrated and reach dangerous levels in the bodies of large predators such as killer whales.
Persistent organic pollutants (POPs) are a group of environmental pollutants that include PCBs (polychlorinated biphenyls), DDTs (dichlorodiphenyltrichloroethane) and PBDEs (Polybrominated diphenyl ethers) from flame retardants. When ingested, POPs are not metabolized or eliminated. These fat-soluble molecules accumulate in fats, such as blubber and only enter the bodies of killer whales through their diet. Use and production of PCBs and DDTs in the United Stated were banned in the 1970s, but these POPs continue to be widely used around the world and all POPs persist in the environment. POPs can reduce reproductive capability and may be one factor in the decline of the Southern Resident killer whale population.
Scientists analyzed blubber biopsy samples from killer whales of the eastern North Pacific Ocean. Experts haven't yet defined a "toxic threshold" of PCBs for killer whales, but they do know at what concentrations these pollutants adversely affect harbor seals. PCB concentrations in most of the killer whale blubber samples surpassed these dangerous levels.
PCB concentration increases with age in male killer whales and in sexually immature females. On the other hand, reproductively active female killer whales showed lower PCB levels than did adult males or sexually immature females. A mother killer whale transfers PCBs to her calf as the calf develops and also through fat-rich milk as the calf nurses.
Transient whales were more contaminated than resident whales, probably due to differences in diet. Marine mammals (the preferred prey of transient killer whales) have higher PCB levels than do fish (which make up the diet of resident whales).
Up to 1,000 new chemicals enter the environment every year, so many other understudied or unknown chemicals could be affecting marine life including polychlorinated paraffins (PCPs), polychlorinated naphthalenes (PCNs), polychlorinated terphenyls (PCTs), personal care products like shampoo and pharmaceuticals such as synthetic estrogens and steroids.
Oil spills can have long-term effects on killer whale populations. Populations of a resident and a transient pod inhabiting Alaskan waters near the site of the 1989 Exxon Valdez oil spill experienced major declines in the year following the spill and have failed to recover to pre-spill. Oil spills especially threaten transient killer whale populations since they may hunt prey animals sickened by exposure to the spill. Killer whales may not be able to detect oil due to poor olfaction.
Limited Food Availability
A key reason that the endangered Southern Resident killer whale population has not recovered is likely due to declines in populations of their main prey, Chinook salmon (Oncorhynchus tshawytscha), from overfishing by humans and habitat destruction. Northern Residents have also recently experienced a higher mortality rate that is probably linked to a reduction in Chinook salmon availability.
Whale watching expeditions bring people close to wild whales and help people learn about them. In British Columbia and the state of Washington, killer whales are the most popular cetacean of commercial whale watching companies.
Higher concentrations and closer proximity of boats can force whales away from their traditional habitats and reduce a killer whale's echolocation abilities when hunting for prey.
The National Oceanic and Atmospheric Administration (NOAA) Fisheries has developed "Marine Wildlife Viewing Guidelines" to protect marine animals. Among other recommendations, the guidelines instruct whale watchers to keep their distance. Impeding the whales' right of way is not allowed. Chasing, harassing, touching, and feeding animals also are prohibited.
Tours to watch whales in the wild are increasing in popularity around the world.
IUCN / The World Conservation Union
IUCN/The World Conservation Union is a worldwide conservation organization. It links together government agencies, non-government agencies, and independent states to encourage a worldwide approach to conservation.
The IUCN's Red List is a system for assessing an animal's relative risk of extinction. Its goal is to categorize and raise global awareness of species that face a high risk of extinction. The killer whale is categorized as "data deficient." There is inadequate information to make a direct, or indirect, assessment of the species risk of extinction based on its distribution and/or population status.
The U.S. Marine Mammal Protection Act (MMPA) of 1972 made it illegal to hunt or harass marine mammals in the U.S.
The primary objective of the MMPA is to maintain the health and stability of the marine ecosystem and to obtain and maintain an optimum sustainable population of marine mammals.
According to the MMPA, all whales in U.S. waters (baleen and toothed) are under the jurisdiction of the National Oceanic and Atmospheric Administration (NOAA).
The MMPA does allow for certain exceptions: native subsistence hunting; taking marine mammals for research, education, and public display; and taking restricted numbers of marine mammals incidentally in the course of fishing operations.
The Endangered Species Act of 1973 (ESA) conserves endangered species and their ecosystems. A species is considered endangered if it is in danger of extinction.
As defined in the ESA, a protected "species" may be a species, a subspecies, or a distinct population segment (DPS).
In 2005, the Southern Resident killer whales of the eastern Pacific Ocean were listed as an endangered DPS under the ESA. The population was estimated at 200 whales in the late 1800s and currently stands at about 85 whales. This DPS faces risks including vessel traffic, toxic chemicals and competition for food, especially salmon. The small DPS is also susceptible to potential catastrophic risks, such as disease or oil spills.
NOAA Fisheries and the U.S. Fish and Wildlife Service (USFWS) share responsibility for implementing the ESA.
The Convention in International Trade of Endangered Species (CITES) is an international treaty developed in 1973 to regulate trade in certain wildlife species. Killer whales are listed under CITES Appendix II: species that are not necessarily now threatened with extinction, but that may become so unless trade is closely controlled.
In Canada, the Species at Risk Act (SARA) became law in 2003. A main purpose of SARA is "to proved for the recovery of wildlife species that are extirpated, endangered or threatened as a result of human activity".
Under SARA, the "West Coast transient" population of killer whales was listed as "Threatened" and issued a recovery strategy to deal with dangers that includes bioaccumulation of toxins in prey items and physical and acoustic disturbances.
The non-profit SeaWorld & Busch Gardens Conservation Fund works on behalf of wildlife and habitats worldwide. The goal of the Fund is to encourage sustainable solutions by supporting critical conservation initiatives worldwide.
The SeaWorld & Busch Gardens Conservation Fund supported a study on killer whale energetics to help determine how whales have solved the complex bioenergetic relationships of energy intake and expenditure and what impact they are eventually having on their system. The study measured the metabolic rates of killer whales at SeaWorld. This data was then used to estimate energy needs of the whales in the wild.
By assessing the metabolic rate of captive killer whales and relating it to heart rate, the study can be used to evaluate metabolic expenditures of free-ranging whales and ultimately apply this information to the conservation and protection of wild whales, such as the endangered population of Southern Resident killer whales.
Scientists all over the world continue to study the abundance, biology, reproduction, migration, and behavior of killer whales.
Marine Zoological Parks
SeaWorld trainers and veterinarians perform regular health exams on the killer whales to monitor and maintain their health.
In the protected environment of a marine zoological park, scientists can examine aspects of killer whale biology that are different or impossible to study in the wild.
The unique opportunity to observe and learn directly from live animals increases the body of scientific knowledge and enhances public awareness and appreciation for wildlife.
Up until the 1970s, killer whales were mainly regarded as a nuisance animal. Attitudes began to change dramatically, mainly due to displays at marine life parks that allowed people to learn about and appreciate killer whales like never before. Killer whales provide the opportunity for zoological parks and aquariums to play a unique and unrivaled role in marine mammal education and conservation.
Marine mammals spend much of their time underwater, making it difficult to observe and quantify certain aspects of their lives. Studying killer whales nursing behaviors in the wild, for example, would require either close, limited observations from a vessel or underwater viewing by humans, either of which would likely cause alterations to the behaviors under investigation.
The study of captive cetacean populations in controlled research settings has provided fundamental information on many species-specific aspects of their biology. Observing cetaceans in marine life parks allow for long-term, fine-scale studies that would be difficult to achieve in the ocean and such studies add to our overall knowledge of cetaceans and supplement fragmented information from observations in the wild.
A contribution to our understanding of the basic physiological processes in killer whales has been derived from captive populations including adaptations to diving, auditory detection, echolocation and learning, reproductive physiology, growth and development, metabolic and energy requirements, health status, immune system function, and genetics.
The utility of these captive studies for health assessment and conservation strategies for free-ranging cetacean populations requires that captive populations are healthy and thriving. In the killer whale and other delphinids, commonly used population health indicators are reproductive success and age-specific survivorship patterns. Recent analysis of captive bottlenose dolphin (Tursiops truncatus) populations, a species closely related to killer whales, demonstrated that reproductive success and survivorship patterns are comparable to or exceed those experienced by their wild counterparts. As such, these captive populations can provide models for understanding geriatric changes and impacts of unique age or event-specific physiologic stressors to wild populations.