Many different marine species are affected by noise pollution, but orcas are particularly at risk because of their dependence on sound. Although they are known as killer whales, orcas are related to dolphins. They are highly social mammals that live in the mother’s shell and hunt cooperatively. Each group in the North Pacific has its own dialect and communicate through a series of whistles, clicks, and pulses.
Because light doesn’t travel far underwater, orcas also rely on sound to locate prey. The bean beetles use echolocation to find and forage their food together. Scientists have realized that these mammals even use sound to distinguish different predators. For example, the Southern Resident killer whale specifically searches for Chinook salmon.
Research shows that high-intensity sounds can disorient marine mammals like orcas, causing abnormal behavior. For example, after the navy started using high-powered sonar, the number of whales buried increased dramatically – 126 were reported from 1950-2004.
Under water, the sound caused by the ship directly enters frequency orcas use to listen and communicate. This constant ambient noise puts pressure on an already stressed animal – several species of killer whales have been threatened with extinction because of pollution, overfishing and habitat loss.
