A rescue mission is under way after a whale was spotted entangled in a fishing net off the coast near San Francisco.
Footage showed the nine-metre (30ft) long creature swimming with its tail trapped in a massive gill net.
It comes as grey whales in the region swim north as part of their annual migration from the waters around Mexico to Alaska.
The animal was first spotted off Laguna Beach in southern California in March, when rescuers attached two red buoys to the net to make it easier to see.
Earlier this week rescue crews attempted to cut the net from the whale’s tail – but whenever they got close it became aggressive and they were unable to continue.
Justin Viezbicke, from the National Oceanic and Atmospheric Administration (NOAA), said the animal “became very reactive”.
Officials from the NOAA and Marine Mammal Center in Sausalito, California, are now searching for the whale north of San Francisco, as it is thought to be continuing its migration.
Kathi George, from the Marine Mammal Center, said crews had also attached a satellite tag to the net last month to track the whale’s movements – but it had since fallen off.
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Ms George said the rescue team will try again to cut the net, or at least attempt to attach another satellite tag, if the creature is spotted again soon.
She said: “Our goal is to retrieve the gear that’s on the whale, so we can learn more about the entanglement and how it happened, so we could use that to inform risk reduction efforts.”
Every spring, grey whales migrate 5,000 miles from birthing waters off California and Mexico to feeding grounds in the Arctic.
