Marine scientists on Thursday used the recorded siren songs of humpback whales in an attempt to lure an injured female and her calf from a shipping channel on the outskirts of the state capital back to San Francisco Bay.
The use of the underwater recordings was scientists' first attempt to direct the whales back to the Pacific Ocean since they appeared in the Sacramento-San Joaquin Delta on Sunday. Their improbable 90-mile journey from San Francisco Bay has taken them through the Sacramento River and the deep-water shipping canal that ends at the Port of Sacramento, where they have attracted thousands of onlookers.
Researchers began playing the sounds of humpback whales from an
87-foot Coast Guard cutter, the Pike, as the tide started going out at midmorning. The strategy did not succeed initially, however. The whales' reacted by swimming away from the sound, rather than toward
Hours later, the whales remained at the Port of Sacramento, where they have been swimming since Tuesday.
The recording procedure worked in 1985 with a humpback nicknamed
Humphrey, which swam in the delta for nearly a month before returning to the Pacific.
But biologists said the situation facing them near Sacramento is more complicated. It involves a mother and calf, rather than a single whale, that are much farther into the delta than Humphrey was. The injuries add another dimension, as scientists say they do not know how the wounds might affect the whales' behavior.
"It's brand new territory. It's not like we're applying something we have a lot of experience with in the past. It's essentially an experiment," said Pieter Folkens, a biologist with the Alaska Whale Foundation who was part of the rescue effort. "We really can't have high expectations of a positive outcome. We're certainly doing our best."
Scientists were using a digital recorder with a playback system to amplify about five minutes of recordings played at intervals. They had hoped the 8- to 10-second sequences would entice the whales to leave the deepwater port and head back down the shipping channel, which parallels the Sacramento River.
"They (the sounds) are different, so the animal doesn't habituate itself. It's like the dinner bell," said Bernie Krause of the Wild Sanctuary in Glen Ellen, who calls himself "the whale whisperer" and was one of about a dozen scientists aboard the Pike.
The lack of immediate response also may be related to the recordings being used. They are of Alaskan whales that might be part of a different pod than the one the mother and calf belong to.
"This is a humpback probably from a different population, probably the Mexico-California population," Folkens said. "So it's kind of like speaking Chinese to somebody from Boston, but at least you recognize that it might be another member of the same species."
Even if the recordings eventually work, scientists said it could take anywhere from several days to several weeks to bring the whales back to the bay.
One concern is the murky water and numerous estuaries of the delta, a vast network of rivers and canals that drains two-thirds of California's land mass. Scientists fear they could lose track of the whales as night falls and are considering marking them with radio or satellite tags that would be attached with suction cups.
If the sound recordings aren't enough, wildlife officials said they would try a different tactic - lining the channel with boats to herd the whales in the right direction, said Frances Gulland, director of veterinary science at the Sausalito-based Marine Mammal Center, which has taken the lead on the attempted rescue.
If the whales start heading toward the bay, a flotilla of Coast Guard and law enforcement boats was due to follow the whales to make sure they didn't turn and head back up the channel. An Associated Press reporter and photographer were on a smaller Coast Guard vessel in the port's turning basin.
Biologists hope to get the whales back into the Pacific Ocean, where food is more plentiful and the salt water can heal their cuts, apparently caused by a boat propeller. The injuries were diagnosed using photographs taken Wednesday as the animals swam in the port.
"The injury on the female is about 2 feet long, 6 inches deep, and has sharp edges typical of a propeller wound. We don't think it's life-threatening," Gulland said. "The calf has a wound that looks a little bit more severe than the female."
The calf's wound was difficult to assess, however, because it is on the animal's underside, below the water line, Gulland said.
Although the injuries appear to be growing larger, the whales likely will not need treatment if they can be returned to their natural sea water habitat, which is cleaner than the fresh water in the shipping channel, researchers said.
Shipping and small boat traffic were halted in the channel, which is 30 feet deep and 200 feet wide. One freighter remained docked at the port, known primarily as an export terminal for California rice.
The next ship was not expected to dock until May 23, giving researchers time to escort the whales.
Biologists had feared the larger whale was entangled in some sort of fishing gear, but what appeared to be an object wrapped around it is actually blubber, Gulland said.
The wounds, which likely were inflicted as the whales made their way up the Sacramento River, appear to go only as deep as their blubber, rather than their muscle, making the injuries less severe than they could have been.
Biologists believe the younger whale is about a year old, although they have been unable to determine whether it is still suckling, or nursing.
The whales likely were on their northward migration from Mexico up the California coast when they were sidetracked, 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, Gulland said.
(Copyright 2007 by The Associated Press. All Rights Reserved.)