I used to use lighter tackle on musky’s, 12# mono on a spinning rod, hit one on Deer lake once in late summer when temps were mid 80’s.
Long battle and the fish was slow to recover, in fact after waching her slowly swim off, 10 mins or so later, I see her sufacing and not doing well at all, more time trying to get her going and hopefully she made it, but I always wondered.
I no longer use light tackle or barbs on my hooks.
You cut a hook and leave it in a musky imho you just probably killed it.
Water temp?
Not sure, but if one of the musky’s/northerns I caught started to take a longer than normal time to revive, I’d back off and look for something else to fish.
Can’t help you on actual temps though, don’t know enough about that.
Al