Predators gone, small fish get bolder

This article is about little fishes that naturally are scared and timid of predators.
But for the fault of human fishing Tuna and Sharks (the principal predators) shrink. Little fishes become bolder: what means that now they take bigger excursions to feed or to go find mates.
In waters untoched by humans, the researches found that the little fish were spotty in their feeding habits.
Using snorkels, scuba equipment and video cameras, a group of scientists captured the behaviour of more than 600 small fishes.
Some parts of the coral reefs, where fish fed on seaweed, where heavily grazed. In other areas, perhaps where predators lurked, there were large tufts of untouched seaweed.
But where fishing was happening, their grazing formed a more even patter across the reefs.

Questions:
Why if humans know about this, they still fishing where there are no supposed to?
Why are not rules in the counties where this happens?