mad-as-a-marine-biologist:

There is no way these sharks would be there if they haven’t been fed. 

Feeding wildlife is unbelievably damaging. If they are eating the food you provide, they aren’t eating what they would normally eat. You are effectively removing them from the food web. And with an apex predator like a shark, you can be sure that the effects resonate all the way through the web.

In essence, you alter that ecosystem. Stop it. It’s naughty.