The whale washed up about 40 feet from the shore Tuesday on Mustang Island. Onlookers watched it thrash about before veterinarian Tim Tristan gave the whale a huge dose of tranquilizers.
Marine mammals beach themselves only when something is seriously wrong, he said.
"This animal stranded for a reason," Tristan said. "It can be heartbreaking, but all we could do was make it comfortable."
A necropsy to see why the whale was sick was scheduled for Wednesday.
Lea Walker, a regional director with the Texas Marine Mammal Stranding Network, said the whale was too big to transport or hold in a tank to rehabilitate.
