SAN DIEGO -- A catamaran provided by billionaire businessman Richard Branson towed the carcass of a 70-ton fin whale out to sea Friday.

The ship owned by Virgin Oceanic arrived at Fiesta Island at around 8 a.m. after traveling south from Newport Harbor. The whale was towed to the island Wednesday afternoon so that whale experts from the National Marine Fisheries Service could perform a necropsy to determine how it died. The necropsy determined that the whale probably died after being hit by a ship.

The pregnant 67-foot whale washed ashore at Point Loma on Sunday. A 5-foot fetus was expelled from the carcass on Tuesday.

The catamaran was towing the remains about five miles west of La Jolla, where it would be sunk in about 800 meters of water by adding "several tons'' of steel, executive director of the Birch Aquarium at Scripps, Nigella Hillgarth said. The 12-mile trip was estimated to last about seven hours, with crews sinking the whale around late afternoon at the earliest, lifeguard Chief Rick Wurts said.

The chosen site was near the Scripps Submarine Canyon, and Scripps Institute of Oceanography scientists would be able to study the whale as it decomposes to find out how a new ecosystem forms around it, a process which could last several years, Hillgarth said.

"There are all these organisms that only live on whale carcasses that turn up,'' Hillgarth said. "Hopefully we'll get really exciting information from that.''

Fin whales, found in oceans all over the world, were nicknamed the "greyhound of the sea'' because they can swim as fast as 23 mph, are the second-largest species of whale and can grow up to 75 feet and weigh 70 tons, according to the National Oceanic and Atmospheric Administration.

Taking fin whales, prized for their oil, was largely banned by 1976. North Pacific fin whales off the California and Oregon coasts are estimated to number around 2,500.