Fears are growing for a gray whale entangled in a fishing net off the coast near San Francisco.
The nine-meter (30ft) long creature was captured on video swimming with its tail trapped in a massive gill net.
It 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.
However, marine rescuers, who have been working this week to try and cut the whale free, told local media that a tracker attached to the animal had broken off and it was now missing.
They have also had to suspend their search due to an incoming storm.
Earlier this week, rescue crews attempted to cut the net from the whale’s tail. But, whenever they got close, the whale became aggressive and they were unable to continue.
Justin Viezbicke, from the National Oceanic and Atmospheric Administration (NOAA), said the animal “became very reactive”.
On the loss of the tracker, he told The San Francisco Standard: “We still haven’t figured out why, but something happened out there where the satellite tag buoy broke off.”
The team were reportedly able to source a new tracker by Wednesday, but by that time the whale had disappeared.