The search for five missing trawlermen was halted late Sunday after their boat sank off southern Ireland, the coastguard said.
Coastguard helicopters and lifeboats took part in the search, which was due to resume at first light on Monday.
The boat's captain, named in reports as Michael Hayes, a 21-year-old Irish student and four Egyptian men were on board the Irish-registered boat, the Tit Bonhomme, which was previously French-owned.
One of the Egyptian fishermen was rescued and was being treated in hospital in Cork but efforts to find the rest of the crew were hampered by bad weather.
The boat is believed to have struck rocks off the coast of Cork.
"The vessel got into difficulties on the approaches to Union Hall/Glandore Bay and the alarm was raised with us at approximately 5:50am (0550 GMT)," a Coastguard spokesman said.
"One individual has been transferred by rescue helicopter to Cork University Hospital and we are currently searching for the remaining five crew members."
Later Sunday, Declan Geoghegan, the operations manager for the coastguard, said: "I'd be very surprised if we are looking for survivors at this stage."