Two Questions About Fish & Cats

If little fish get eaten by bigger fish, who get eaten by bigger fish, who get eaten........ What happens if there are no more little fish?
Most cats hate the water, and very few swim in the open ocean, so how come so much of the world's baitfish (little fish) populations are being harvested to feed pet cats?

The way the marketers of cat food portray it, you would think cats would die for a feed of fish.

Maybe they should?

Old engraving of deep sea fish