The Joint Rescue Coordination Centre is searching for a man in the waters south of Yarmouth.
In a tweet, the JRCC says around 4 a.m. this morning, they were notified of a man-overboard situation from a fishing vessel south of Yarmouth.
Lt.-Cmdr for the JRCC Brian Owens says the four person crew went out last night.
He says the three crew members slept on board that night while the captain stayed awake in the wheelhouse.
When the crew woke around 4 a.m. they did not find the captain on board. Owens says a may day was issued and the JRCC responded.
The CCGS Clarks Harbour, a CH149 Cormorant, CH130 Hercules and PAL aircraft have been tasked with locating the man.
The fishing vessel the man had been on was escorted to Yarmouth by the CCGS Corporal Teather. The JRCC says all remaining onboard are safe.
This story will be updated as more information is released