How does overfishing affect the food chain?

 

To the left is what the food chain is meant to look like. However after overfishing the fish such as tuna, mackrel and sometimes even the small fish get fished away so the shark has nothing to eat. Overfishing has a domino effect on the food chain. You take out a fish such as tuna and then you wipe out multiple other species. If the tuna is gone the shark can't eat and dies. Then no one eats the mackrel and their population rises so much that the small fish stand no chance and also die. Then the shrimp like creatures population rises dramatically killing all one celled life. No matter which fish is fished by humans, if humans make it extinct or dramatically lower their population the entire ocean suffers