The crew of the Poseidon Princess called for help in the early morning hours, saying their boat was capsizing off the coast of West Pubnico.
The Joint Rescue Coordination Centre put out a call for boats in the area to help around 1 a.m. AT.
Two other fishing boats responded, and found three people in a life raft and a fourth in the water, all of them wearing survival suits, according to Reetha D'Entremont, the wife of the ship's captain, Martin D'Entremont.
By 5 a.m. all were rescued.
'They're shaken up'
D'Entremont said the three crew members aboard the 20-metre fishing vessel — her husband and his brothers, Lee and Oscar D'Entremont — were all taken to a Shelburne hospital for treatment.
The fourth person, she said, was a Fisheries Department observer who was taking samples. He was taken by ambulance to a hospital in Yarmouth. His injuries are not known.
"They're shaken up, they're waiting to see doctors, they're bruised. I don't think anything is broken. They had a hard time getting out of one of the life rafts and into the boats," D'Entremont said.
The observer, whose name has not been released, was rescued from the water, she said.
"He didn't get in the raft, he was just floating in the water and they don't know if he was unconscious or what," D'Entremont said.
It's not clear what caused the ship to capsize. According to D'Entremont, the vessel sank.
The Poseidon Princess is operated by Inshore Fisheries Limited, a fish processing and harvesting company in Pubnico.