"Those sea creatures are extremely destructive, which isn't in line with the nature of this planet which is still very young, that's why the elders had categorized those sea creatures as invasive species.
If both of you have already roamed around as you said, then you should have noticed that a lot of land is already barren, which was caused by those sea creatures.
Their nature is very destructive that they are extracting the very essence of all the land that they go into, which results in the barrenness of all those lands which would last for thousands of years.
In fact, if our people aren't fighting those creatures, then almost all the land on this planet is probably already wiped out and consumed by those sea creatures who don't have any restraints and only know how to destroy and gain energy.
