This uncontrolled breed-mayhem on that planet may be, because it was this situation out of the norm. From what La'an said, i had the impression that they systematically used the humans for breeding and food.
The Young ones could be left to their own devices in a controlled manner. Much like birds, the younglings of some species also attack each other. The strongest survives.
I like to think that, at home, the adult Gorn pretty much have their kids under control.
But, yeah, they reproduce out of the box.
It's because, aliens ...
Under the Skin - with Scarlett Johansson. There's almost no dialogue. No exposition about anything, or names - just the short lifespan of an alien. Disguised as a woman, they're part of what seems to be a hidden alien colony living amongst humans.
The soundtrack is haunting, hypnotizing and beautiful.
It's also slow and sad.