Lots of good ideas and perspectives in this. I appreciate it. I don't call myself a fisherman, but I have fished in MT, CO, MO, NM and AZ and have caught a few. I have spent many more hours fishing than catching fish. I've pondered on this, and realized that my chances of catching a fish are not going to magically improve merely because I'm in a survival situation, the fish don't care.
My own experience at fishing with hook and line has led me to learn how to build and use fish traps for true survival situations. Yes, they are illegal in most states, but in a true survival situation, so what? I practice by building traps and then after catching a few fish to be sure they work, I tear them down and release the fish. IMHO making fish weirs and traps are a skill, like fishing knots, that anyone who spends time in the outdoors should learn.
Having said that, I do carry fishing gear, similar to kits already so well described,including swivels, in my PSK. Fishing gear is so useful for so many things and weighs so little, it's crazy not to carry it. It could even be used to catch fish, maybe someday.
As for cleaning fish, I've never done anything but cut open the belly and remove the entrails, then cook them. I really like them with a strip of bacon and a wedge of lemon on the inside, wrapped in aluminum foil and put on the coals. Mmmmm.
Just my thoughts.