I've just read this reposrt from Blue Voice about the death of 900 dolphins earlier this year in Peru. 900 dolphins don't just 'die' of natural causes. I was particularly interested to hear their views...

The Peruvian government has released a report on the mass mortality of at least 900 dolphins along the coast of Peru that states that “natural causes” and “evolutionary forces” were the cause of death.

BlueVoice, which has funded extended and extensive research conducted by Peruvian veterinarian and marine mammal expert Dr. Carlos Yaipen Llanos, believes that conclusion is nonsense. We present here a narrative history of the mortality event and Dr. Yaipen Llanos’ hypothesis that acoustical trauma followed by rapid ascent leading to catastrophic decompression is the most likely cause of death. Dr. Yaipen Llanos makes no assertion that seismic testing for oil is associated with the dolphin mortality. However BlueVoice suggests that this form of extremely loud testing makes the seismic tests a primary “element of interest”. Seismic testing was taking place in approximately the same time frame and geographical location as the dolphin mass mortality."

Read full and extensive article here:
http://www.bluevoice.org/news_perudolphins.php