Great project. But it makes me think that just dumping some tank traps down there (Three steel bars welded normal to each other) would work well to snag and tear nets and, if they don't encounter a net, support some sea life.
I just meant it inspires me to think of a cheap and easy way to go "monkey wrench gang" in other places. In fact governments could even do this in places where they are trying to restore fisheries.
OTOH snagging on a boulder is very disruptive to fishing and is quite dangerous, can result in wholesale loss of the gear and threaten the vessel. That will actually cause fishers to think twice.