First spotted by the Coast Guard's Rio Vista Station on Sunday, the mother and calf later swam up the Sacramento River and have now reached a dead end at the turning basin of the port.
Marine experts spent three hours examining the mammals on Wednesday morning as hundreds of curious bystanders flocked on the levee to catch a glimpse of the unusual scene.
Frances Gulland, a veterinarian with the nonprofit Marine Mammal Center in Sausalito who examined the whales, said during an afternoon press conference that both mammals appeared to have wounds that are non-life threatening. The whales, a 45-foot female and her 20-foot calf, most likely were hit by boat propellers several days ago during their ill-fated journey into the San Joaquin/Sacramento rivers.
Gulland said that the calf has a "more serious wound," but she only got two glimpses at it because of its location. Even so, she said there's no need to treat either mammal if they can get them back to the saltwater soon.
Contrary to earlier reports, neither appeared to be entangled in any netting, Gulland said, noting she and others will examine photos taken this morning for more information.
Mid-morning Thursday marine mammal experts plan to begin a two-fold rescue operation using underwater humpback sounds to try to lure the creatures down the river.
Gulland did not have any estimates on how long it would take to encourage the whales to return to the ocean.
"I'd love this (the rescue) to be over in a week," she said.
The last time a similar rescue was attempted was in 1985 when Humphrey was lured back to saltwater in about two days.