I come to gather that 60# Mono would be the all around test for the combination of shark\tuna setup.
You guys agree???
not too light for sharkin and not too heavy for tuna.
I'm not talking braid here....
For most fish 60# is fine and it's probably even correctly matched tackle for fish to 200 lbs..
However my problem with it sharking is that when you hook something like a 300 lb blue dog, which you really want to fight and release quickly to get your lines back in the water for that mako, it just takes too long with line under 80# or 100#.. hook a trophy shark and you are really undergunned; sharks come in all sizes and there's no telling what will show up.
As far as tuna, 60# is fine if you are sure the tuna will be under 200#.. up here there's no telling what you'll get, 200# is still a smaller fish, and I can't comment of what's found in your waters for tuna.