There is no sign of a blue whale that was entangled in fishing line off the Southern California coast.

The search resumed Monday for the massive mammal, which was last seen at nightfall Friday dragging several hundred feet of line.

Though the whale was estimated at 80 feet long, rescuers fear the stress and strain could weaken and eventually kill it.

Peter Wallerstein of Marine Animal Rescue said in a best-case scenario, tension created when rescuers attached a buoy Friday may have caused the line to snap.

Rescuers have freed entangled whales before, but have not tried to free a blue whale so they do not know how it would react.