Newt (one of my YellowCat teachers), taught me to put the hook on perch, by going right thru on the bone centerline near the tail. He explained that it "wounds" them in a manner to make them flutter & churn the water. In which that sound & movement attracts big Yellows. Also, he said it keeps them alive more & look more natural as compared to the top under the dorsal fin.
Of course, if you are on the river, they will not last long as they will drown by water going thru their gills in reverse. Unless the current is not strong. And it was on the Brazos, but at normal bank. Plus, the trotline was angled, so it would have an area of at least 3 leaders off (under) a shelf below, where the Yellows were taking refuge from the current.
Think of it this way, as a big Yellow is vacuuming or scooping (engulfing) its meal, it does not sound of alarms, as the leader line with hook is towards the rear of the bait fish. By swallowing it, only when something odd is felt, does it try to expel the hook, which usually grabs on its way out of the stomach. Each hook is different, circle or "J" or others. But interesting is the Tru-Turnn hooks which has a unique bent angle on the "J". It seems when they expel, it turns the hook, which helps it to grab something more than ordinary "J" hooks.
In fact, I have caught two good size Yellows with Tru-Turn hooks that made that "turn" & dropped into the bottom gill slits. On a YellowCat, they go further under than Blues or Channels. In there (the slit), it is almost impossible to come unhooked, without using hands. And neither of them exhibited any signs of trying to tear out of their predicament.