Image: Humpback whale in Sacramento Delta River.
U.S. Coast Guard via EPA
Spectators watch as one of two stranded humpback whales partially surfaces out of the Sacramento Delta River by the Port of Sacramento during the week of May 14 to May 20.
updated 5/21/2007 7:40:06 PM ET 2007-05-21T23:40:06

The journey of a wayward whale and her calf back to the Pacific Ocean hit a snag Monday when the pair reversed course and began heading back up the Sacramento River.

The humpbacks, nicknamed Delta and Dawn, had traveled more than 20 miles south from the Port of Sacramento since taking a wrong turn and swimming toward the state capital more than a week ago. But they turned around again Monday afternoon, even as scientists and the Coast Guard tried to position more than a dozen boats in front of them.

“They’re at this point lost. We don’t think they have any clue,” Rod McInnis of the National Marine Fisheries Service.

Their route includes sloughs leading to muddy deltas that could trap the whales, who appear to have been wounded by a boat’s propeller. Crews were trying to maneuver boats to the mouths of side channels to keep the whales from going off course.

Other obstacles
The two also will have to make their way through the pylons of four bridges on their 90-mile trek. Once they reach San Francisco Bay, the whales will have to swim under the Golden Gate Bridge to return to the ocean, Wilson said.

The whales started moving toward the Pacific around 3:30 p.m. Sunday from the Port of Sacramento, where crowds gathered over the weekend to catch a glimpse. They swam as far as the Rio Vista Bridge in the rural Sacramento-San Joaquin River Delta region before turning around.

Scientists theorized that vibrations from traffic were upsetting the mother and calf, but the whales could not be coaxed forward even when the drawbridge was raised to halt the flow of vehicles.

“We were thrilled to get them down the channel yesterday, but I’m afraid that was the easy part,” Carrie Wilson, a marine biologist with the California Department of Fish and Game, said Monday.

Federal officials have authorized researchers to fire darts carrying a satellite tracking device beneath the mother’s fin to ensure authorities can still locate the whales if they wander from the main channel into the delta’s maze of river branches.

Noise 'hazing' possible
If the two continue to head upstream, authorities could resort to “hazing” by banging on metal pipes dangling underwater with hammers, said Steve Edinger, assistant chief of the Department of Fish and Game.

The goal is to “make as much noise to be as obnoxious to the whales as possible” to get them to move back toward the ocean, Ed Sweeney, a member of the U.S. Coast Guard Auxiliary said from his boat Monday.

No one is certain why the whales decided to go back downstream in the first place, but Jim Oswald of the Marine Mammal Center said the change may have been spurred by tug boats. The tugs’ engines fired up about 100 yards away from the pair, and the sound may have had an influence.

“The tugs were out in the basin, and the whales decided to follow them,” Oswald said.

There was no indication that the whales were in poor health, Wilson said. “They have been very consistent and moving along at a good pace,” she said.

The appearance of the humpbacks was not the first time a West Coast whale has veered so far off course during the annual spring migration northward. A humpback named Humphrey swam in the delta for nearly a month in 1985 before scientists used recordings of whale songs to lure him back to the Pacific.

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