WEST SACRAMENTO, Calif. - The recorded siren songs of humpback whales played from a Coast Guard cutter yesterday as biologists tried to lure an injured whale and her calf out of a shipping channel and back toward the Pacific Ocean, 90 miles away.

It could take weeks to get the two whales back where they belong, scientists said. Still, hundreds of people lined the riverbanks to watch the progress yesterday.

The procedure worked 22 years ago with another humpback that wandered for nearly a month in the Sacramento-San Joaquin Delta before returning to the ocean, said Bernie Krauze of Wild Sanctuary in Glen Ellen, Calif.

"Hopefully, these will do the same thing we did for Humphrey the whale when Humphrey was stuck," Krauze said before starting recordings that he described as the sounds of humpback whales feeding.

"It's like the dinner bell."

If sounds aren't enough, wildlife officials will try a different tactic - lining the channel with more boats to herd the whales in the right direction, said Frances Gulland, director of veterinary science at the Sausalito-based Marine Mammal Center.

Biologists hope to get the whales back into the Pacific, where food is more plentiful and the salty water can heal their wounds.

The cuts were apparently caused by a boat propeller. Scientists checked them Wednesday using photos of the animals swimming in the Port of Sacramento. If the whales can be returned to their natural seawater habitat, which is cleaner than the fresh water in the port, they likely won't need treatment, researchers said.

The two likely had been on their northward migration from Mexico when they were sidetracked and spotted Sunday in the lower Sacramento River, biologists said. Because they are at the end of their hibernation season, they have less blubber to rely on for fuel than they would later in the summer or fall.

They spent Wednesday exploring the muddy waters of the Sacramento River basin as people flocked to see them.

Shipping and small-boat traffic were halted in the basin, which is 30 feet deep and 200 feet wide. The next ship was not expected to dock for another week, giving authorities time to try to escort the whales back to the Pacific, said Teresa Bledsoe, administrative clerk at the Port of Sacramento.

A flotilla of Coast Guard and law-enforcement boats planned to follow the whales to make sure they did not head back up.

One concern is the murky water and many estuaries of the delta, a vast network of rivers and canals that drains two-thirds of the land in California. Scientists fear they could lose track of the whales and said they were considering tagging them.