50 whales were beached on Coqueiro beach, Santiago Island, and another 42 on the Sal Island coast.
The whales were spotted coming close to shore by a group of fishermen. They said the large pod had begun heading towards the coast on Saturday afternoon.
With no support from the authorities, local people tried in vain to push the whales back into the sea. One local said: 'We fought to get them back into sea, but they keep returning, some died, I don't know what's going on.'
Officials from the Ministry of Environment came to Coqueiro beach, but could do nothing more than take samples from the dead animals.
Authorities say the reasons for this 'collective suicide' will probably never be known although in 1947 a similar incident happened at the same beaches.
Another local said: 'It is a sign that God has given, but humans can not perceive, at my age, I've never seen anything like it.'
