"Today is a big day for the beluga and all those involved in its rescue," Sea Shepherd France said in a tweet.
In the saltwater tank, the whale "will be monitored and get help, with the hope that what it suffers from can be cured," it said. "It will then be released in the sea with, we hope, better chances of survival."
Drone footage on Monday showed the white whale coming up for air as it turned slow circles in the lock just below the water's surface.
Drone footage on Monday showed the white whale coming up for air as it turned slow circles in the lock just below the water's surface.