Editors: This 10:15 a.m. update on Friday, March 31, adds information about the end of the U.S. Coast Guard's search for Shigeru Nakano and adds details about the expedition and accident. Editors: Photographs of the dead and missing individuals are available through the Associated Press. A spokesman for the U.S. Coast Guard said this morning that it considers it unlikely that Japanese researcher Shigeru Nakano, 37, could still be alive following Monday's boating accident in the Sea of Cortez, and it has ended its search for him. The spokesman said the Mexican Navy continues to search from Bahia de Los Angeles, the base of the research expedition. On Thursday, searchers recovered the body of UC Davis ecology professor Gary Polis. Three other members of the expedition were found dead earlier this week; four survived the accident and swam to safety. Those survivors and the remaining participants returned late Thursday evening to Sacramento on a university-chartered private jet. Escorting them back from San Diego were UC Davis officials, including Chancellor Larry N. Vanderhoef, Agricultural and Environmental Sciences Dean Neal Van Alfen, and campus counselors. The survivors traveled on Thursday from Mexico to San Diego, where they were questioned for two hours by U.S. officials. At the same time, a contingent of colleagues and family of the Japanese researchers arrived from Kyoto at the San Diego airport. Chancellor Vanderhoef was there to meet them. After their questioning was finished, the accident survivors also met with the Japanese group, giving them their first detailed account of what had happened in the accident. The researchers were part of an expedition of 23 people who were visiting the Sea of Cortez to study the ecology of spiders and scorpions that inhabit the area's islands. The Japanese scientists had visited colleagues at UC Davis the previous week, then traveled to Mexico for the research expedition. They were Takuya Abe, 55, an animal ecology professor, Masahiko Higashi, 45, a mathematical ecology professor, and Nakano, an associate professor of aquatic ecology. All three scientists were from the Center for Ecological Research at Kyoto University in Japan. The expedition members gathered in the town of Pueblo de Bahia de Los Angeles, about 300 nautical miles south of San Diego, Calif. It included Polis, the expedition leader; Michael D. Rose, 27, a UC Davis postgraduate researcher in Polis' laboratory and assistant expedition leader; six people from the U.S. and England who had signed up for the project through EarthWatch, a nonprofit environmental group; and 12 other participants, including five from UC Davis. On Monday morning, 17 people in two boats left to conduct research on Isla de Cabeza de Caballo, located about 4 nautical miles off shore. Between noon and 2 p.m., the group left the island to return to town. The wind had risen, waves were four to six feet high, and one of the boats, which carried Polis and eight other people, including the three Japanese researchers, began to fill with water. The engine shorted out and died, and the boat was battered by waves, and the group could not bail it out. Then a big wave knocked it over onto its side. All the boat's occupants stayed with the boat, with great difficulty, for two or more hours. They had life jackets and buoyant seat cushions. During those horrible hours, Gary Polis died. Mike Rose and Shigeru Nakano used all their strength to keep the group together. Eventually, five people struck out for land, swimming against the big waves and strong currents. Postgraduate researcher Gary Huxel, undergraduate student Sarah Ratay, graduate student Becca Lewison and graduate student Ralph Haygood, all of UC Davis, made it to two nearby islands. One of the Japanese researchers also made it to an island but died there. Huxel, 38, is a Davis resident. Lewison, 28, of New Jersey, is a Ph.D. candidate in ecology. Ratay, of Corning, 20, is majoring in genetics. Haygood of Fresno, 35, is a Ph.D. candidate in population biology. When the party in the other boat arrived at port and realized their friends had not returned, a group went back out to search, including University of Arizona master's student Patty West. Polis' boat was reported missing to officials in Mexico at 10:30 p.m. Monday night. UC Davis Chancellor Larry N. Vanderhoef has said the accident was "the most tragic in the history of the university" and "our hearts go out to all of the families." The director of the National Science Foundation, Rita Colwell, said in a statement, "I feel shock and a deep sadness over the loss" of the researchers. "As we mourn those who have lost their lives or are missing, we also celebrate their examples of courage and commitment. "Like so many colleagues who diligently pursue a better understanding of our world, these researchers put their commitment to knowledge before their comfort and personal security. The research they were conducting was funded by the National Science Foundation, but the impact of their work is so much broader. Their loss is overwhelming. Our hearts and minds are with their families, friends and colleagues." Because the incident occurred in Mexico's territorial waters, the search effort has been led by the Mexican Navy using a helicopter, fixed-wing aircraft and high-speed boat. The U.S. Coast Guard used a helicopter and a C-130 airplane. The offices of U.S. Sen. Dianne Feinstein and Congressman Doug Ose have been working with the U.S. Embassy in Mexico City to assist in the search efforts, and to assure the safe return of all those who took part in the expedition. The News Service will update this advisory as more news becomes available.