The spear fishing thing has been done. I was pretty interested in spearfishing until my speargun broke. I got all the freediving breathing down. Maybe I could take one spearfishing. People have taken huge billfish that way. You gotta shoot them a few times though. Let me see if I can find a picture. By the way, people spearfish for yellowfin tuna all the time. I know they are smaller than bluefins but still!
John, by the way, sorry about the message board. You know I didn't go out with the intent to crash it. Do I get royalties for the increase visitation?

;D
Oh yeah, this fish below is the World Record spearfished bluefin tuna. 655.2 lbs! It was speared by Paulo Gaspar in the Azores.