John and Elvis are Dead

I just realized (ok, I knew but was trying to block it out) that this week is the start of baby seal clubbing season. I am by no means an expert or informed participant in the topic for obvious reasons. I did learn that Canadian fishermen do it in the off-season as a supplement to their fishing income. It makes sense to kill animals for food and other uses. What I don't understand is why it has to be baby seals, who are vulnerable and can't defend themselves or get away. And even if it is ok to kill a baby seal, why can't they do it with a gun or something that will cause immediate death? I'm assuming it takes multiple whacks to kill. Isn't one of the unwritten human codes of conduct not to prey on the innocent and helpless? We're not supposed to eat our fellow humans and we are not supposed to pick on those weaker than us.