Here's the thing, in a lot of the reef you're allowed to drop your anchor and smash everything to pieces but if you were to take one of those pieces home with you, you will end up in front of a dolphin firing squad. There are thousands of miles of reef that aren't in the national park (technically not part of the GBR) though, and many of these are pretty much free from restrictions. I got some nice leathers and colt corals off the edge of a wharf in Brisbane along with some copperband butterflies, a blue dash butterfly and a lunare wrasse.
It can be frustrating though, if you do get stopped, for some reason no one has a problem if you pull a coral trout out of the water and stab it to death on the deck but if they find you catching a small fish with a net and taking it home alive there seems to be no end of troubles.
I dont know what the deal is with bringing things back into the US either. I was thinking about bringing a leather frag home with me on the last trip but with my delicate greencard status i really dont need any hassles from customs.