A major search and rescue effort is underway for a missing fisherman who fell from a commercial boat off the Sunshine Coast early this morning.

The missing man is understood to be a 45-year-old, last seen wearing a black shirt and grey shorts on the fishing vessel Barameda-K.

Senior Constable Murray Lyons from the Sunshine Coast Water Police said the search area is now about 133 square miles offshore from Double Island Point.

"At this stage the conditions have been reasonable although they are starting to deteriorate," he said.

"There are obviously great fears held for his safety having been in the water for so long and searches are continuing."

Mr Lyons said the 45-year-old was last seen about 2:15am by the boat's skipper and it was still not known how he went overboard.

Police said it was understood the man was not wearing a life jacket.

The search included eight helicopters, two fixed-wing aircrafts, one jet, two water police vessels, two fishing vessels and a Coast Guard vessel.

The skipper of the Barameda-K, Pete Rockliff, and his 14-year-old son were also taking part in the search for the man.

The missing man is a spanner crab fisherman who also has family on the Sunshine Coast and is understood to be an experienced seaman.

Initial reports suggested the boat was drifting in calm water at the time.

An urgent PAN-PAN radio alert has gone out to all boat users across the Sunshine Coast, asking them to keep an eye out for the man if they are travelling through waters off Double Island Point and Rainbow Beach.

The search will be suspended at last light today and will resume Thursday at dawn.