All 28 pilot whales stranded in Golden Bay have died, after their pod became trapped at the high tide mark on Farewell Spit this morning.
Eleven died in the first hour and another a short time later.
The Department of Conservation (Doc) this afternoon confirmed a decision had been made to euthanise the remaining 16 whales, and programme manager Hans Stoffregen said Doc was disappointed at the outcome.
The whales were destroyed this afternoon.
Earlier today, Mr Stoffregen said something must be wrong with the whales, as pilot whales can usually survive for days in the same conditions.
"It's unusual that they would die so quickly."
Mass whale strandings are not uncommon at Farewell Spit.
They swim into the relatively shallow water during high tide, but the tide recedes very quickly and they become stuck on the sand.
In January, more than 80 whales died after a mass standing of 99 pilot whales at Farewell Spit.