If they are protected, then you don't hunt them no matter what you yourself think. In your other thread your wondering why new laws are being brought in against spearfishing, yet you've just pretty much answered that yourself. You breaking the law costs other spearfishers who respect the laws. You get the fish, they get the bad reputation.
If I was spearfishing and saw some fish that big, I'd leave em alone out of the respect that they've survived that long. They have a major part to play in the ecosystem, and if the law is still there to protect them, then there is a reason for it. Amazingly, the experts that actually decide on these rules are a lot more knowledgeable about the whole situation than you are, so respect what they say you can and can't do, and realise that it's for the good of the oceans.