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Orcas (or killer whales) are large, powerful aquatic apex predators. There have been incidents where orcas were perceived to attack humans in the wild, but such attacks are less common than those by captive orcas. [ 1 ]
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.
The whales make groans, pops and belches typically at frequencies around 500 Hz. The purpose of the sounds is not known but may be a form of communication between whales within the same group. Northern right whales responded to sounds similar to police sirens—sounds of much higher frequency than their own. On hearing the sounds, they moved ...
Researchers found an increase in common dolphin sightings in the English Channel and Hebrides, and a decline in white-beaked dolphins in the Hebrides.
A hunt begins with a chase followed by a violent attack on the exhausted prey. Large whales often show signs of orca attack via tooth rake marks. [83] Pods of female sperm whales sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using them to repel the attackers. [89]
The data suggests, therefore, that human sources of mortality may have a greater effect relative to population growth rates of North Atlantic right whales than for other whales. The principal factors known to be retarding growth and recovery of the population are ship strikes and entanglement with fishing gear .
"Those whales, that have spent their entire lives in captivity, their closest relationship is with humans. They are the ones who have provided them with food, care, activities and social relations.
Bryde's whales have not been reported as taken or injured in fishing operations. They are sometimes killed or injured by ship strikes. Anthropogenic noise is an increasing concern for all rorquals, which communicate by low-frequency sounds. [8] These whales are protected off the US by the Marine Mammal Protection Act of 1972. [8]