Hi Jace,
One word to answer your questions,
Exhaustion.
Mike Hutchinson hooked a black marlin of about 60 kg about 4 yrs ago in Moz. the fish towed him about 4-6 km b4 he landed it after a 2 hr battle, and he had to tow it back to shore cause it could not fit on the ski.
Fishingski anglers normally fish in pair or more and if someone hooks onto a steam train, then the guys normally tie their ski's together to create more resistance to tire the fish out quickly.
If you by chance hook a whale then cut the line.::H