Its dorsal fin is low and triangular, resembling a light-colored flag when the dolphin swims just below the surface of the murky yellow Yangtze River, hence the name "white-flag" dolphin. It has smaller eyes compared to oceanic dolphins. As China developed economically, pressure on the river dolphin grew significantly. Industrial and residential waste flowed into the Yangtze. The riverbed was dredged and reinforced with concrete in many locations. Ship traffic multiplied, boats grew in size, and fishermen started using wider and more lethal nets to fish. Noise pollution caused the nearly blind animal to collide with propellers. Populations of the dolphin's prey declined drastically in the late 20th century, with some fish populations declining
