tgl, big halibut really aren't hard to measure on the surface, they are pretty docile and will just lay there until there head is lifted out of the water, I released 1 a few years ago that was 8'8", I know this because I laid a 1025 rod on its back and it was 2" longer then the rod.
Nootsack, if you shoot it it won't qualify as a world record, even harpooning it will disqualify it.