The search for a crewman missing after a commerical fishing boat capsized south of the Alaska Peninsula, killing two men and injuring another, was called off Thursday night, the Coast Guard said.

Officials had scoured more than 1,730 square miles in the North Pacific for two days, said Petty Officer Sara Francis.

"The chances of finding someone alive in these kinds of water temperatures after 24 hours is extremely low," Francis said. "After 48 hours, that chance drastically reduces."

She said the water temperature was 48 degrees.

The 49-foot, 50-ton Ocean Challenger, whose home port is Adak in the Aleutian Islands, disappeared Wednesday about 60 miles south of Sand Point, a community off the tip of the Alaska Peninsula.

Officials said they did not know what caused the boat to capsize and sink. Francis said the Coast Guard was investigating, and planned to talk to the survivor on Friday.

Residents in Sand Point, a city of 940 about 570 miles southwest of Anchorage, said the weather has been severe, with high winds and 20-foot seas.

The survivor, 28-year-old Kevin Ferrell of Lynchburg, Va., was assisted in the water by a rescue swimmer and hoisted to safety by a Coast Guard helicopter. Ferrell, the only person wearing a survival suit, was in critical condition Thursday, the Coast Guard said.

The bodies of skipper David "Cowboy" Hasselquist, 51, of Hoonah, Alaska, and crewman Walter Foster, 26, of Westport, Wash., were pulled from the water.

The missing man, Steve Esparza, 26, of Kodiak, was not wearing a survival suit, the Coast Guard said.

The Ocean Challenger had been fishing for black cod near the Sanak Islands and was traveling back to Sand Point when it disappeared, said vessel owner Barry McKee.

Audette, the cannery manager, said he knew the fishermen on board the capsized boat.

"It's come as kind of a shock to us," said cannery manager Audette. "We are all affected by this kind of thing. We are pretty tight-knit group here."