Mexican navy Capt. Elias Bonilla said from Ensenada on Tuesday night that fishermen had recovered three bodies.

A U.S. Coast Guard helicopter and a C-130 search plane flew to Bahia de los Angeles in the Gulf of California to join Mexican navy boats in scouring the waters and coastline for the two people still missing more than 24 hours after the accident, which occurred midday Monday.

Four scientists aboard the 22-foot inflatable boat managed to swim to a nearby island in the bay after their boat began sinking in four- to six-foot seas, university spokeswoman Lisa Lapin said.

Lapin identified one of the dead as Michael Rose, a 28-year-old postgraduate researcher who recently had knee surgery. She said another victim was one of four Japanese professors who were part of the weeklong expedition.

The research team was headed by scorpion expert Gary A. Polis, chairman of the UC Davis department of environmental sciences and policy. Lapin confirmed that Polis, 53, was among the missing.

The team had arrived from California only a day or two earlier to carry out studies on scorpion and spider populations on the desert islands off the coast of Bahia de los Angeles, a fishing village eight hours south of Ensenada by road.

Two boats were carrying the 20 team members back from one of the islands after a work session Monday morning; one boat, carrying 11 people, returned safely to the shore, but the other foundered in the heavy seas.

"My heart goes out to the families. This is a tragic, tragic moment for them," UC Davis Chancellor Larry Vanderhoef said.

"If this is not the worst day, it is one of the worst days in the university's history."

Alfredo Zavala, the Ensenada-based head of Mexico's island nature reserves in the Gulf of California, said he had been scheduled to join Polis on Wednesday for research projects at Bahia de los Angeles. He said Polis had been coming to Baja California on research trips for more than a decade and knew the region extremely well.

"Dr. Polis is recognized at an international level and has published articles in magazines such as Nature and Ecology as well as scientific journals," Zavala said. "He is a professional, serious person, and always has worked closely with his Mexican counterparts."

He noted that Bahia de los Angeles "is a beautiful place scenically, but it is very isolated. There are no basic services; there is just one pay telephone for the whole town."

The gulf is known for sudden windstorms, or chubascos, that last two or three days, Zavala said. The winds blow through the Channel of Whales just beyond the bay and along Angel de la Guarda island, generating dramatic changes in the sea conditions in a very short time.

"When the chubasco blows, the local people don't even move," Zavala said.

The only municipal official in the town, Fermin Smith, said by telephone that local fishermen joined the U.S. survivors and a small group of navy seamen from a local encampment in searching for survivors Monday and Tuesday.

Smith, grandson of the town's founder, said about 400 tourists, mostly Americans, have swelled the town's population of 800 Mexicans in recent years. The town, ringed by mountains, lives off commercial fishing and the growing tourism trade.

One of the team members, who identified herself as Caitlin Harvey, was reached at one of the village's hotels, but she declined to answer questions about what happened, referring a reporter to the U.S. Consulate in Tijuana, which in turn referred queries to the U.S. Embassy in Mexico City.

At a news conference in Davis, Lapin said the visiting Japanese professors were from the University of Hokkaido and the University of Kyoto.

She said the university had sent a chartered van to Bahia de los Angeles on Tuesday to bring back the survivors of the ordeal. The four who swam to safety were identified as undergraduate Sarah Ratay, graduate students Becca Lewison and Ralph Haygood and post-graduate researcher Gary Huxel .

Rob German, a friend of Lewison, said she told him Tuesday evening that the boat had taken on water in rough seas and flipped.

"She made it back. She's alive, and for the most part she's well," German said. "But she's pretty banged up; it was a three- to four- hour swim back to shore."

A U.S. Embassy spokesman said the Mexican government had accepted a U.S. offer for logistical help in the search. The Coast Guard helicopter was dispatched from San Diego, and the C-130 plane flew from Sacramento on Tuesday to assist Mexican navy boats, some of which came from Guaymas.

Polis is one of the world's leading experts on scorpions and literally wrote the book on the topic: "Biology of Scorpions," published by Stanford University Press in 1990. He is also the author of "The Ecology of Desert Communities" and coauthor with Laurence Pringle of "Scorpion Man: Exploring the World of Scorpions."

He had spent much of the last seven years on a project funded by the National Science Foundation, studying the effects of the El Nino drought on the desert flora and fauna of Baja California and 62 islands in the Gulf of California, which Mexico calls the Sea of Cortez.

He joined UC Davis in 1998 after nearly a decade as a professor at Vanderbilt University. He started studying scorpions in 1973 when he was a graduate student at UC Riverside.

Former department Chairman Alan Hastings said of Polis: "He's a wonderful individual, a fabulous Italian cook. He's just a pleasure to be with in every way. The department is in a very, very somber mood today."

Smith reported from Mexico City and Tamaki from Davis. Times education writer Kenneth R. Weiss and Mexico City researcher Jose Diaz Briseno contributed to this story.