A search for a 23-year-old woman in the Pacific Ocean 4 1/2 miles west of Channel Islands Harbor was halted because of darkness, a Coast Guard spokesman said. The woman, Colleen Halstron, was presumed dead, officials said. "We are not hopeful of ever finding her," said Lt. Dennis Fahr. "We are not optimistic of finding her at this time due to the length of time in the water. One of the survivors said she was not a good swimmer and we're not sure whether she had a flotation device or life jacket." Halstron's fiance, Mike Echols, 20, and Dan Rogers, 35, were saved by the pleasure boat "Lopsided," after their 11-foot boat was inundated by waves, Fahr said. The Oxnard residents were described as incoherent after an estimated 11 to 12 hours in the water.