A search for 17 fishermen missing for more than 30 hours in the icy Southern Ocean after their South Korean fishing boat sank has been called off.

Twenty survivors and five dead crew were recovered from the water after the No 1 Insung went down yesterday 1000 nautical miles (1850km) south of New Zealand, about halfway to Antarctica.

About 30 hours had elapsed since the vessel sank, meaning there was no reasonable expectation any more survivors would be found, Rescue Co-ordination Centre New Zealand search and rescue mission spokesman Dave Wilson said.