A wayward mother whale and her calf still have miles to go and obstacles to overcome as they try to return from the Sacramento-San Joaquin Delta to the Pacific Ocean.
On Sunday the humpback whales traveled through a deep water shipping channel from the Port of Sacramento toward the Pacific, nearly a week after taking a wrong turn and swimming inland to the state capital, the U.S. Coast Guard said.
The whales 90-mile route to the ocean includes sloughs leading to muddy deltas that could trap them. They appear to have been wounded by a ship’s propeller.
The duo will also have to make their way through the pylons of four bridges to reach the San Francisco Bay, and will have to swim under the Golden Gate Bridge to return to the ocean, said Carrie Wilson, a marine biologist with the California Department of Fish and Game, from the deck of a boat following the pair.
The whales traveled southwest from the Port of Sacramento, where crowds had gathered to catch a glimpse. As darkness fell Sunday, the Coast Guard escort that had followed the whales all day ceased trailing the duo so the vessels would not accidentally hit them.
Nicknamed Delta and Dawn, the humpbacks started moving toward the Pacific at around 3:30 p.m. Sunday, swimming at about 6 miles-per-hour toward Rio Vista, a town located about 45 miles from Sacramento. From Rio Vista it is another 60 miles to San Francisco Bay.
No one is certain why the whales decided to change course, 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. They’ve been on the move (ever since),” Oswald said.
During their journey, boats will be positioned at the mouths of tributaries where the whales could possibly go off course.
“We’ve got a bunch of metal pipes and hammers, and if we need to, … we can give the other boats pipes to bang on to persuade the animals not to turn in the wrong direction,” said Wilson.
Wilson said there was no indication that the whales were in poor health. “They have been very consistent, and moving along at a good pace,” she said.
The whales’ plight has been followed closely, and hundreds of people have gathered along the banks of the Port of Sacramento to get a glimpse of the pair. People were also appearing on the banks of the Sacramento River trying to get a glimpse of the retreating whales, Wilson said.
Wildlife experts decided on Friday to leave the whales alone for the weekend, since heavy recreational boat traffic in the delta could have complicated any efforts to move them.
If the whales don’t continue on their current course toward the ocean, marine mammal rescue crews will resume trying to lure the pair in the right direction by playing recorded sounds of other humpbacks feeding. That strategy worked in the case of a humpback named Humphrey, who in 1985 swam in the delta for nearly a month before returning to the Pacific.