The Marine Mammal Center responded to Pier 39's "K-Dock," the area where sea lions congregate on floating wooden platforms, at about 12:30 p.m., Marine Mammal Center spokesman Jim Oswald said.
Oswald said it appeared the animals have what looks like fishing line around their necks.
The rescue team successfully deployed a dart with a mild sedative into one of the two sea lions at about 1:50 p.m., Oswald said.
Once the sedative kicked in, the rescue team slowly approached the sea lion, brought it to shore, put it in a rescue carrier and is driving it to the center where a veterinarian will take off the debris wrapped around its neck.
"It's tricky to do," Oswald said of the rescue. "We don't take them lightly."
If the entanglement were more severe, the rescue crew could have opted to take the wire off on site, he said.
The rescue of the second sea lion appears to have become more complicated; the sea lion was scared by a tour boat and has disappeared into the water, Oswald said.
He said crews will wait at the pier to see if it returns. If it does, they will repeat the process used to rescue the first sea lion.