Bran, I have a friend who does underwater photography & video as a hobby. He mostly does rare & endangered species of fish, some of which are no bigger than 2", but occasionally ventures into the park and looks at trout. After his last outing, in a very heavily fished area of the park, he mentioned seeing similar results. Many, many fish over 20" that had probably never felt a fisherman's hook.
Last time I talked to him, he wad been in contact with park fisheries about doing some brook trout photos & video high up on Lynn camp, and was trying to aquire the use of a horse to haul all his gear. His wetsuit & camera equipment are apparently very heavy. I'll email him today to see how that is coming, and if he has any photos he wouldn't mind sharing with the forum.