Gar and Stripers sure will make crappie quit biting so I suspect Pike will too. I don't know if they actually run them off or if the crappie just hunker down and go from an offensive mode to a defensive mode when larger predators start pokin round.
I use six-pound line when tight-lining jigs and eight-pound line on my slip-float rigs so we have a chance to land those catfish, gar, drum, striper, hybrid white bass, white bass, green carp and what have you that occasionally pester us.