simple solutions in the shark cage

My poor hands have taken a beating, thanks to Marco and his gi-normous mouth.  In using food reward for training, I have suffered significant bruising and it has made training unpleasant.  I asked another trainer (a more well-paid, and therefore assumed to be more learned) for advice and was told to punch him in his snout and tell him "no".  Sometimes I did, simply because it hurt so much and I needed to tell him NOT to eat my fingers!  But it never seemed to have much of an impact, and a minute later he was snapping in big gulps at the treat.

Not training him was worse.  I resorted to trying a variety of gloves to protect my hands.  Normal, cop-kevlar gloves saw holes torn in the the thumbs. Not working.  Gloves meant for filleting fish protected my hands, but left me with cramps because they were so stiff that bending the fingers to grip the treats was tortuous. I found a happy medium with a lighter weight glove meant to protect from knives but the big lummax, though not piercing, was still bruising my thumb with his teeth. 

Viola!  I found the answer last night.  This may not surprise most men, who already know that duct tape is the answer to any question.  It was to mine!  I made a "thumb cast" by wrapping duct tape in a dandy little blanket, layer upon layer, around my thumb.  It fits nicely in the glove and I don't feel his teeth at all.  I tried it without the glove, and just the thumb cast and one time Marco grabbed and pull the bandage, to which he received a sound rebuke (rebuke sounds nicer than saying I yelled and gave his muzzle a whack!) and after that he took the treats very gently.  He does not respond by fainting away or being hesitant, but stopped mugging with his entire mouth.  It is possible that, since I don't feel his teeth, I don't expect to be hurt and therefore am not snatching my hand back, or something like that.  I don't know.  All I know is that my duct tape thumb cast has solved the problem that $50 gloves did not!