Threats

In captivity killer whales are very responsive to humans. They are easily trained to dive, leap, and fetch objects on cue, making them popular attractions at aquatic zoos. Scientists also use captive killer whales as research animals to study behaviors—such as echolocation, reproduction, growth, and development—that are difficult to study in the wild.

In the wild, killer whales are protected by both U.S. and international law. The Marine Mammal Protection Act, passed by the United States Congress in 1972, makes it a federal offense to harm or harass any marine mammal. Since 1982 the International Whaling Commission has banned the commercial hunting of all whales, dolphins, and porpoises. The killer whale is considered at low risk for extinction by the World Conservation Union (IUCN), a nongovernmental organization that compiles global information on endangered species.

Even with legal protection, however, scientists fear that a number of human-created problems threaten killer whales. Some killer whales have been captured from the waters around Japan and Russia for public display. Scientists suspect that widespread pollution, including chemicals in the oceans from agricultural runoff and oil spills, has damaged the ocean habitats in much of the killer whale’s range. Fish and other prey absorb chemical contaminants into their bodies, and killer whales feed on these contaminated animals. As a result, the number of killer whales debilitated by disease has increased. In the Pacific Northwest, pollution and overfishing have reduced salmon populations, limiting the availability of a favorite killer whale prey.

Direct interactions with humans have also affected killer whale populations. Whale-watching expeditions are a popular boating activity. Boaters have cruised too close to killer whale pods, preventing the animals from hunting for food or inadvertently separating mothers from their calves. Easily disturbed by boaters, killer whales may move quickly to evade a boat or they may exhibit aggressive defensive behaviors. These actions sometimes cause boats to accidentally collide with the animals and injure them. In addition, fishing crews occasionally entangle killer whales in their large nets by accident. Scientists fear that these human interactions may be the reason that the killer whale population in the Pacific Northwest has plummeted by 20 percent since 1996.