A 15-year-old boy has been rescued after his fishing boat capsized in the frigid Bering Sea off Alaska’s coast. His older brother and cousin, who were on the trip, did not survive.

Derek Parker Aghnaanga, set sail with his 35-year-old brother, Sidney Kulowiyi, last Friday to catch halibut, their mother, Vina Kulowiyi, told The New York Times. Their cousin had also joined them on the trip.

The group — from Savoonga on the northern coast of St. Lawrence Island — was supposed to return early Sunday, according to the Coast Guard, but never made it home. Derek’s brother and cousin died sometime after the small boat flipped, according to the rescuers.

Derek’s mom called him a “survivor,” writing on Facebook that “he was never afraid the whole time.”

“He lived on prayer with no food and water,” the mom said.

Derek clung to the top of the capsized skiff for days, Adam White, the captain of another fishing boat who helped rescue the teen, told local news outlet KTUU-TV.

“I mean, that’s one tough kid,” White said.

Coast Guard planes and helicopters began searching for the skiff Monday after family members reported the three missing the night before.

After Derek was found, the Coast Guard coordinated the rescue with White’s boat, the “Northwest Explorer.”

Video of the rescue shows the boy in a bright yellow jacket kneeling atop the overturned skiff. The boat’s crew tosses the boy a line, tugging the skiff closer until they can pull him into a rescue basket.

The boy was experiencing symptoms of hypothermia when he got onto the boat, the Coast Guard said. The fishing boat crew warmed him with blankets and hot packs, its captain said.

“Through the teeth chattering, he had mentioned that his brother was still under the skiff and then he said that in the previous night before our rescue that his cousin had slipped away off the top of the skiff,” White said.

The bodies of Derek’s brother and cousin were found after the teen was hoisted to safety near St. Lawrence Island — a remote Alaskan island that’s closer to Russia than it is to the United States.

Alaska State Troopers identified the two who died as Kulowiyi and 34-year-old Barton Rookok.

The Associated Press contributed to this report