Definitely an early 1950s classic pose. Of course, back at the time both the picture and the pamphlet were new, the old dude wasn't that old, maybe in his 40s, and obviously interested in more than just fish.
I have a hunch that one of these days I'll stumble across actual porn, which will then raise some interesting cataloging questions. It would qualify as historic material, but would it be relevant to our museum's mission? And do I bother noting just who made the donation so future generations will know exactly who to thank for the vintage smut?