Marine scientists said Wednesday that the massive operation to rescue two humpback whales yielded valuable information about the endangered species even though they will never know why the pair swam 90 miles inland or what caused them to suddenly turn tail back to the ocean.
Officials said they assumed the mother and calf whales, which
were first spotted near Sacramento on May 13, slipped out of San Francisco Bay to the open sea late Tuesday night or early Wednesday
The unpredictable due were last seen at sunset Tuesday meandering less than 10 miles from the Golden Gate Bridge after traveling 25 miles southwest from another busy bridge. The convoy of boats that accompanied them across the bay to keep traffic at a distance abandoned their escort service when it got dark.
"If they have gone out and made their way past the Golden Gate, they have done so quietly," said Bernadette Fees, deputy director of the California Department of Fish and Game.
To make sure the whales did not take another wrong turn, two government boats were launched Wednesday morning to look for them
in the Pacific Ocean, Fees said. Rescuers planned to rely on reports from commercial vessels and Coast Guard patrols to determine if the humpbacks still were in the bay.
But as the afternoon wore on, producing only a false sighting of two gray whales, officials grew increasingly confident that the humpbacks, which were injured by a boat during their two-week sojourn inland, were on the move and made plans to stop searching for them.
"If we don't see them, we are going to call it," said Jim Oswald, a spokesman for the nonprofit Marine Mammal Center, a private scientific and rescue organization.
Despite the apparently anticlimactic end to the humpbacks' saga, which has attracted thousands to Northern California waterfronts, biologists said the chance to closely observe the pair was invaluable for science. It was the first time the same humpbacks were studied in the wild for so long, according to Fees.
The information scientists gathered includes sound recordings, logs of their behavior and activities, and tissue samples from both the mother and calf, which will be analyzed to determine if they come from a pod of whales that traverse sea from Mexico to California.
"All those things are very hard to get. So what we are doing is filling up the knowledge bank on humpback whales in the wild," Oswald said, adding that the experience could prove helpful in approaching other stranded whales.
Biologists originally had planned to attach a satellite tracking tag to the mother humpback, but gusty winds and malfunctioning equipment stymied them. Distinct markings on both whales' tails were photographed so they could be identified in the future, Fees said.
Officials said they had not tallied the cost of trying to goad the whales back to the ocean, a 10-day effort that involved playing recordings of other whales, surrounding them with boats, blasting them with fire hoses and banging on metal pipes dangling beneath the water.
They speculated Wednesday that a dose of antibiotics given to the whales on Saturday to try to slow the damage from their wounds may have marked a turning point since the pair began their hasty retreat from the Sacramento-San Joaquin River Delta after that.
Biologists said the saltier water where the mother humpback whale and her calf had been swimming since leaving the delta helped reverse some of the health problems caused by long exposure to fresh water.
In the end, those involved in the rescue effort said they did not know if the various methods had hastened the whales' exit or hindered it. But they insisted the expenditure of time, people and money that went into the operation was justified, if not required, under wildlife protection laws.
"We certainly have a moral obligation as the agency assigned to protect them to do everything practical to get them safely into their natural habitat," said Brian Gorman, a spokesman for the National Oceanic and Atmospheric Administration.
Fees said biologists theorized the humpbacks' next stop might be the Farallon Islands, located 27 miles offshore of San Francisco, a popular feeding ground for whales.
They did not rule out the possibility, though, that the pair might follow in wake of their famous predecessor, Humphrey, a humpback that strayed into San Francisco Bay in 1985 before reappearing five years later.
"If we learned anything about these two, it is that they will do what they do when they want to do it," Fees said.
Associated Press writer Lisa Leff in Vallejo contributed to this
(Copyright 2007 by The Associated Press. All Rights Reserved.)