The overgrowth of algae poses a major problem for coral reefs. fish eat algae. why would intensive fishing contribute to the overgrowth of algae

In the open ocean, especially around the surface, one of the main sources of food for fish would be the algae that grow at the surface & photosynthesize with the sun. Without fish to regulate the amount of surface algae, they overgrow and block the sun from the organisms on the coral reef.

Without sun, the reef is not able to sustain themselves & it's down hill from there.

I hope this helps!