I've never fished for halibut, but...  how do you measure the length of a live halibut and still have a boat?  It's my understanding that bringing a big one on board risks staving it in.

PS.  The first halibut I ever ate was a slab of a giant fish, buttered and baked, and I have never encountered anything to match it.  It was as dense as swordfish, but moist and tender  --  a memorable experience.