It, for me is unimaginable to deliberatly kill a living thing for enjoyment, it takes a certain kind of mind to kill one animal for fun, let alone 5 dolphins.
I still have a haunting memory of my first slingshot, I shot a marble at a bird on the top ledge of a church, and I hit it, it was not my intention to actually kill the animal, I didnt think i would even hit it.
But when it fell to the ground and I saw what I had done, the guilt and remorse were enough to let me know it was wrong and it wasnt something that should ever be repeated or enjoyed.