I read that No Boundaries Lodge in Southern Oman tagged about 200 big GT last year, but they didn't recover singe GT yet.
I was very curious that the areas are not big, but no GT was recovered.
When I discussed this issue with Hungry Jack, he said they are probably dead. After thinking for a while, I thought that could be possible though I was very reluctant to believe it.
We assume fish becomes alive when we see them swim sway.
We release all GT as other GT fishermen do. When I fished Fiji, we had a big GT over 50 kg and we spent a little longer time to release fish because we took many pictures of the monster GT. The big GT barely swam sway.
Same thing happened to a big AJ we caught on a jig in NC a few years ago. The big AJ was exceptionally big over 50 kg and we spent longer time to take several pictures before releasing. But the big AJ couldn't swim sway.
The high mortality of GT is the only logical explanation of decline of GT populations of many once famous GT fishing grounds though Catch/release is the general practice in those destinations.
It it is fact, the only solution not to kill GT is to release big GT while they are on the water like we catch/release giant in P.E.I., Canada.