It is believed one man was on board at the time, a fisherman who is believed to have been checking on lobster pots.
Aran Lifeboat was dispatched to the area and recovered the boat last night but no-one was on board.
The Coastguard helicopter and lifeboat crews have resumed a search of the area this morning.
The sun rises behind the Sliabh Aughty hills, as the search continues in #Galway Bay for the missing occupant of a boat, found abandoned last night. @RNLI crews from the Aran Islands and Galway City are at the scene. pic.twitter.com/kGZXJIofAb
— Galway Bay Weather (@galwaybaypics) November 23, 2017