Whales

Threats to Whales

Every year, in Europe alone, more than 2 million people go whale-watching. Watching whales and dolphins has socio-economic benefits for local people and visitors get to enjoy a spectacular and educational experience. Many whale watching operators, however, do not adopt guidelines to limit their impact on the animals and marine environment, sometimes moving too fast and too close to them. The impact of noise, pollution and disturbance on whales is disastrous. Research has showed that whales who were disturbed too much suffered from reduced reproduction. Due to a large amount of boats on the water, fin whales of the Laurentian Channel have even curtailed the amount of time they spend deep sea, shortening their feeding time dramatically. Long term shortened feeding time may affect fin whale health and reproduction. Several studies on Humpback Whales in Canada demonstrated how this species reacts to whale watching vessels. Groups scatter, changing direction or leave the area entirely. These changes can be noted when the boats are still several kilometres away. Industry growth shows both Canadian and American whale-watching boats competing for good spots to view whales. Sometimes more than 50 vessels, both commercial and recreational, may follow a single group of 10 to 20 whales.

Some species of small whales are caught as by catch in fisheries for other marine life. In the tuna fishery, thousands of small whales and dolphins were drowned in nets each day, until specific measures were introduced such as fishing gear modifications, contributing to a reduction on the mortality of these creatures.

Environmentalists have long speculated that whales are endangered by the sonar used by navies. Scientists suggested that sonar is connected to whale beachings and decompression sickness in these whales. Mass whale beachings occur in many species, mostly though, in beaked whales that use echolocation for deep diving. The combination of the high pressure environment of deep-diving with the disturbing effect of the sonar causes decompression sickness. Their exaggerated startle response occurring during deep diving may alter their orientation and cause their rapid ascent.

Conservationists are concerned that seismic testing used for oil and gas exploration may damage the hearing and echolocation capabilities of whales and suggest that such testing may also be responsible for beaching. Other human activities have been suggested to adversely impact whale populations, ranging from the unregulated use of fishing gear which catches anything that swims into it, to collisions with ships. Environmental toxins and the combination of toxins have been shown to cause hearing loss by inhibiting the function of outer hair cells in the cochlea of the ear, and exposure to these toxins might affect whale echolocation, leading to beaching.

Whales are also threatened by climate change and global warming. As the Antarctic Ocean warms, krill populations, that are the main food source of some species of whales, reduce dramatically.