Answer -Because of overfishing of the 2, it would allow the seaweed to overgrow meaning it could become invasive at some point. That means driving away or killing any other species that live in the said area.
Explanation
-Think about it like a garden. If you take away too many ladybugs from someone's garden. the aphid population would rise in the garden. Leading them to eat and destroy all the plants that were already there. like overfishing, if you take all the lobsters and snappers, the seaweed would grow and make all the other plants and species go away.