SAN DIEGO -- Boaters should be on the lookout Monday for a baby gray whale about 20 feet long that found its way into San Diego Bay.

The whale was spotted near the USS Midway Museum about 1:30 p.m. Saturday, Coast Guard Petty Officer Brian Ramirez told The San Diego Union-Tribune.

"Hopefully, it will find its way out," he said, adding that there were no further sightings by evening.

Jim Milbury of the National Marine Fisheries Service told the newspaper whales sometimes take a detour into bays while migrating up and down the coast.

Pacific gray whales give birth in the waters off Baja California, then pass San Diego in the spring on their way to Alaskan waters as part of their annual 12,500-mile migration.

Calves are about 15 feet long at birth.

A gray whale came into San Diego Bay in 2000 and never found its way out; it washed ashore dead in Point Loma about two weeks later. About the same time, another whale was seen in Mission Bay, but it apparently found its way out.