Personal experience:
        There are two things about big sharks. 1. They are very hard to kill.
2. They are just as difficult to keep alive. Back in the early fifties,
when the first Sea-World was being stocked, we, on Catalina, trapped a
few big sharks. In order to keep them alive, we had to walk them around
a circular tank for hours. All volunteers welcome. Ten minutes on and
half an hour off. Finally they'd begin to wiggle and move on their own.
A good time to get out in case the shark remembered how long since his
last meal.
        Art