SOUTH SAN FRANCISCO (CBS/AP) — Two wayward dolphins discovered in an industrial canal in South San Francisco appear to have returned to San Francisco Bay.

Marine Mammal Center spokesman Jim Oswald says rescuers did not find the dolphins in Colma Creek on Friday morning. They believe the animals managed to make their way back to the bay.

The two bottlenose dolphins had been swimming in the small canal, which runs through an industrial area of South San Francisco, since Wednesday night, attracting crowds of onlookers.

One of the dolphins may have been sick from being in the brackish water too long.

Scientists had said tides would likely determine when the dolphins left.

(Copyright 2012 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed)