The carcass of a gray whale was found Monday offshore in the Hermosa Beach area, while a live younger gray whale was seen in Marina Del Rey, the Los Angeles County Fire Department Lifeguard Division said.
According to lifeguards, the carcass of a 15-foot whale was seen about ¼ mile off the coast.
"Due to heavy fog this morning, the current whereabouts of the carcass are unknown," officials said Tuesday.
Both the NOAA Fisheries West Coast Region and the Los Angeles County Department of Beaches and Harbors were notified to help monitor its location.
Meanwhile, the live gray whale was seen in the main channel of Marina del Rey throughout the day Monday. Marine rescue officials were also keeping an eye on its position.
Boaters were asked to "navigate with caution" in the area.
Gray whales are in spring migration season, making the annual trip northward from Baja California to Alaska.
Last week, two dead gray whales were found in the San Francisco Bay. Marine experts said one of them died from severe malnutrition.
The center said the number of gray whales entering the San Francisco Bay this year has been "abnormally high." It said the animals are also staying much longer in the bay.
Padraig Duignan, the center's chief research pathologist, said it was likely the malnourished whale didn't have enough reserves built up to survive her journey north.