Wayward Whale Getting Escort Back to the Sea : Animals: Scientists drive the six-ton baby away from a boat channel in Petaluma but say its troubles are far from over.

A wayward gray whale swam up a narrow boat channel and nearly reached downtown Petaluma on Tuesday, thrilling onlookers but alarming experts who quickly ushered it back toward San Francisco Bay.

Banging on metal pipes dangling in the water, a team of state and federal officials persuaded the baby whale to swim out of the channel after it briefly became trapped amid pilings a quarter-mile south of downtown.

“Mission accomplished,” Capt. Mike Wade of the state Department of Fish and Game said with a grin shortly after the whale re-entered the deeper waters of the Petaluma River. “That channel is very shallow, and we were worried the guy would run aground.”

Despite the successful operation, experts predicted that the whale’s troubles are far from over. As dusk fell, three boatloads of volunteers and government scientists were trailing about 100 yards behind the disoriented whale, herding it slowly toward the river’s mouth.

“We are using hammers to bang on capped metal pipes that make a sound that repels the whale,” said Peigin Barrett, executive director of the Marine Mammal Center in Sausalito. “Hopefully, it will keep moving, but we’ve got a lot of water to cover.”

Tuesday’s episode was the latest chapter in the whale’s curious saga, which began Saturday when it was seen cruising the calm, brackish Petaluma River.

Experts say the whale, which appears healthy, probably took a wrong turn during its migration north to Alaska, winding up in inland waters 30 miles from the Golden Gate.

“This darn animal must be pretty confused,” said Joe Cordaro, a wildlife biologist with the National Marine Fisheries Service. “Sometimes gray whales like to explore little inlets. Maybe this one did that and just couldn’t find its way out.”

Whatever the explanation, the whale has become an instant cause celebre , drawing hundreds of fans from all over Northern California. Residents have given it two names--Phyllis and Petaluma Pete--because its sex is unknown, and posted a sign on U.S. 101 that reads: “Drivers Caution: One Mile to Whale Crossing.”

On Tuesday, camera-toting spectators lined the river’s banks and breakwaters hoping to catch sight of the six-ton whale surfacing to spout. The crowd included retirees, construction workers on their lunch breaks, amateur scientists with binoculars and students ditching school.

“This is a big thrill,” said Julie Tarantino, who brought her four children to see the famous leviathan. “How often do you get to see a whale swim right next to you, blowing water into the air? It’s pretty cool.”

Fred Martin, a retired maintenance worker, agreed, but said he hoped the adventurous mammal would soon “get smart and get back on track.”

“What if some kook chases her with a boat, and runs her up on a bank?” Martin said. “You just never know these days.”

Since its appearance Saturday, the whale has shown particular preference for the tiny Petaluma Marina. On Sunday, the whale lollygagged amid the docks for about seven hours, delighting a crowd of about 300, Harbor Master Wayne Kipp said.

“She was close enough to touch,” said Kipp, whose office has become ground zero for the whale-loving public. “Maybe she’s just a social creature. Who knows?”

The gray whale, a bottom-feeder that lacks the dorsal fin found on most whales, is listed as an endangered species but has made a strong comeback in recent years. Its most distinctive characteristic is the heart-shaped stream of water it forms when it spouts.

The whales are at the very end of the spring migration from their breeding ground in Baja California to Alaska. One danger of herding the Petaluma whale, scientists said, is that it may become stressed, using up fat reserves it needs for the journey north.

“It’s living off its blubber now, so we don’t want to do anything to make him use up all his energy,” Cordaro said.

The whale’s troubles are reminiscent of those of Humphrey, the humpback whale who meandered far off course in 1985, becoming trapped in a Sacramento River slough 25 miles south of the capital. In a massive, dramatic rescue, volunteers were able to coax him to safety through a small opening in a bridge that blocked his path.