Answer: If over-fishing occurs it can create a void in the food chain. For example, if someone over fishes salmon, then the bass that eat said salmon can starve, and die off, then others predators that eat bass can starve and die off as well. It's a chain reaction like with the dinosaurs. How the ashes from the meteor killed the plants and then the herbivores died, then the Carnivores and omnivores starved and died as well. The chain reaction starts with one thing, over-fishing to fish, is like the meteor to the dinosaurs.
If you're overfishing at the top of the food chain, and acidifying the ocean at the bottom, you're creating a squeeze that could conceivably collapse the whole system that's my answer
