Some 145 pilot whales that stranded themselves on a remote New Zealand beach have died.

A hiker discovered the pilot whales in two pods about 2 kilometres apart late Saturday on Stewart Island.

About 75 were already dead and conservation workers decided to euthanise the others due to their poor condition and remote location.

Conservation workers are hoping to save some of the eight pygmy killer whales that remained stranded on Monday at the other end of the country in an unrelated event.