Almost 100 pilot whales have died in a mass stranding on New Zealand's remote Chatham Islands, conservation officials said yesterday. Most of the marine mammals beached themselves over the weekend but rescue efforts were hampered by the area's isolated location, about 800km east of the South Island, the Department of Conservation (DOC) said, reported Agence France-Presse. By the time wildlife officers reached the area, 69 whales had already died, and others had to be euthanised, said DOC biodiversity ranger Jemma Welch. The causes of mass strandings remain unknown despite scientists studying the phenomenon for decades.