Letter: Stranded whales could be victims of earthquake noise

Sir: Just as humankind relies most heavily on its dominant sense of sight, so whales and dolphins rely on their ability to hear sound images of their underwater world. By this means they undoubtedly carry out their ocean migrations and navigate coastal waters.

The largest sound sources by far in the ocean are natural and stem from underwater earthquakes. Other sources still of great magnitude include the detonation of oil seismic survey airgun arrays. As it happens seismic survey is in progress in the general geographical area where the Tasmanian whales referred to in your article "The whales' tale" (1 February) stranded. However, mass strandings are not uncommon in the Pacific "Ring of Fire", quite possibly as a result of sub-sea vulcanism.

Naturally, since attention has been focused on the plight of people following the Asian tsunami, there has been little if any information concerning the stranding of cetaceans in the general area of the earthquake epicentre. Perhaps this information may yet emerge. What can be said with certainty is that a sub-sea earthquake has the potential to damage cetacean hearing and disorientate the animals, leading to strandings. Earthquakes are unavoidable natural phenomena, which may or may not result in tsunamis.

The legal principle of causality states that an event must be preceded by its cause. Whales may strand following an earthquake event. There is neither evidence nor likelihood that, in stranding, they predict either an earthquake or a tsunami.

Professor RODNEY COATES

Trefor, Anglesey