The search for the Russian seaman was called off on Monday evening and was unlikely to start again on Tuesday, maritime officials said.
Nobody had seen the man fall overboard from the Dutch-registered ship Victoriaborg, which was caught in high winds and waves of 6-7 metres high about 220 kilometres north-west of the port of Brest in Brittany, western France.
A surveillance plane searched for him but without success, while a rescue craft towed the Victoriaborg to safer seas.
Swiss yachtsman Bernard Stamm and his crewmate Damien Guillou were picked up by a Norwegian container ship off the Scilly Isles, in British waters, after they radioed for assistance overnight.
A 12-year-old boy, who had been helping his stonemason father, died after a wall collapsed on him on a building site in Normandy on Monday.
Local prosecutors say the accident may have been caused by the storm.
Storm Dirk caused more chaos in north and west France:
- Power was cut off to 240,000 households, 130,000 of them in Brittany, according to electricity supplier ERDF;
- Ferry traffic from the British port of Dover was suspended and some companies stopped services from Saint-Malo, Ouistreham, Le Havre and Dieppe in France;
- Rail services were interrupted between Brest and Saint Brieue, Brittany, and Caen and Cherboug, Normandy, but were returning to normal on Tuesday, officials said;
- Emergency services in Finistère, the most western point of France, were called out for 1,000 incidents, mostly trees blocking roads;
- A Panama-registered boat lost about 30 containers off Brittany, the contents were not dangerous;
- Floods hit part of the Finistère town of Morlaix with shops, including a supermarket, flooded.
The storm eased off in Normandy and Brittany on Tuesday morning but forecasters maintained a flood alert and warned that the storm would head south, hitting the Ardèche, the Drôme and the Isère in the Rhone valley.