RANCHO PALOS VERDES, Calif. –  Rescuers say they'll hold off until Saturday on efforts to free a blue whale tangled in a fishing line off the Southern California coast.

The whale, believed to be about 75 feet long was spotted spouting and diving Friday afternoon in a channel between the mainland and Santa Catalina Island. It was dragging a long trailing line with an attached buoy, possibly from a lobster or crab trap.

A disentanglement team from the National Oceanic and Atmospheric Administration arrived at the scene before sunset and attached a larger buoy to keep track of the whale but decided to hold off on efforts to cut or detach the line until Saturday.

It's unusual to see blue whales — the world's largest mammal species — entangled and authorities want to proceed cautiously.