Dropping your lead down even 100x in a day doesn't do shit to the reef. A trawler cuts a 100yd+ swath across the bottom. It's like clear cutting, and he does it for about 30 miles a day, minimum. If somebody did that to the land above water, people would shit themselves. They just don't know where their shrimp come from.
I haven't eaten shrimp in about 2 years, since I saw how destructive it was first hand.