It's easy to talk about sustainable fishing, but few us have what it takes to put actions behind our words. Shark fishing, in particular, is a purely recreational activity -- so the only way to make it remotely ethical is to let the sharks go after they've been reeled in.
And if the shark is too tired from his ideal to go along with the "release" part of "catch and release?" Technically, the right thing to do would be to jump into the water after it and help resuscitate it. Still, this probably isn't something you see every day: