Fish population dying

Yes.

Naturally, a cycle increases and decreases the number of predator and prey.

The cycle is in the next bracket.

(When predators kill prey, the population of prey decreases. This means less food for predators and the predator population decreases. This means less hunting of prey and prey population increases. This means more food for predators and predator population increases.)

This is totally different for man.

Man feed on all kinds of animals, big and small.

Even when one species is threatened to extinction, Man can depend on other source of food.

Man is unlikely to be in this cycle.

Human beings are exploding with population.

Every 5 seconds, a baby is born.

As the population of man increases, it means more people becoming fisherman,and those fish don't have a chance to reproduce from humans unlike other animals and decrease to extinction.