That fish is impressive to say the least. The only way I can imagine a fish becoming that large would be in some instance where trout are present in a tailwater all the way to another lake. Like Boone lake for instance, where the watauga and s. holston both run into it. I believe trout can be found almost all the way down to the lake. If a fish were to make it into the lake after becoming large enough to avoid being a bass meal, then it could sit back and feast on bait fish and small panfish and become massive. I don't know anything about that river she caught that fish from, but wow, it must have been a shock to hook into something like that.
"I've got to stop wishin, I've got to go fishin"