Probably knife...With ballistics, noise, registrations, and so on it'd be too difficult. Actually a knife would be hard to get through all that blubber. Probably a trash bag or whatever plastic bag I could fit over their beast like heads. Suffocate them. Less mess and work, ease of access to tools and of effective disposal of the weapon. Yeah. trashbags. Id of course need something to incapacitate them. Probably a cattle prod or something like that.