Noise pollution caused the nearly blind river dolphin to collide with propellers. Ship traffic, in the Yangtze River in China multiplied, boats grew in size, and fishermen employed wider and more lethal nets. Stocks of the dolphin’s prey declined drastically in recent decades as well, with some fish populations declining to one thousandth of their pre-industrial levels.

Efforts were made to conserve the species, but a late 2006 expedition failed to find any Baiji in the river. Organizers declared the Baiji “functionally extinct”,which would make it the first aquatic mammal species to become extinct since the demise of the Japanese Sea Lion and the Caribbean Monk Seal in the 1950s. It would also be the first recorded extinction of a well-studied cetacean species (it is unclear if some previously extinct varieties were species or subspecies) to be directly attributable to human influence.

Article and image from Beauty of Animal

The undersea noise issue has steadily increased in crescendo with a greater awareness of the potential effects on marine mammals of military sonars, seismic surveys, shipping and boat traffic, oceanographic experiments, as well as other noise sources. What has made the noise problem so intractable, though, is the inherent difficulty in studying marine mammals, particularly cetaceans, and the effects of sound on them. Free-ranging whales and dolphins, which are visible above water for only short periods of time, are notoriously challenging research subjects.

Over the course of the last couple of decades, scientists and conservationists have become increasingly aware of threats to biodiversity that are diffuse and hard to assess but are, nonetheless, of great concern. Three examples are climate change, chemical pollution and marine noise pollution. Of the three, chemical pollution has received the greatest attention and response mechanisms are already enshrined in a host of national and international law. However, by contrast, noise pollution in the marine environment is still an emerging, but undoubtedly serious, concern. Its implications are less well understood than other global threats but like chemical pollution it is usually largely indetectable
to everyone but the specialist. It is also difficult to comprehend, particularly for those that live above the sea surface and who do not readily appreciate the profound importance of sound to marine animals, particularly the whales, dolphins and porpoises, in the oceans.

Article and image from WDCS