>

This would incentivize shitty bad for the environment ships on the water. Anyone who could get their hands on a ship and some firepower, is how I see this turning out. Real unscrupulous types. How is this going to help again?
Faster, EU. At that speed there won't be any biodiversity left by the time the ban comes into effect. >

What we need are mines that prevent bottom trawling. They could sit harmlessly just off the ocean floor, but if a trawler snags them they are triggered by pressure sensor just as they are hauled on board. Their presence in an area should be loudly declared to operators and insurance companies, as their purpose would be to make it too expensive to illegally fish an area. No people ever need to be actually harmed. >

That's a very expensive operation.  Any sort of electronics that has to sit on the ocean floor requires constant maintenance.
I would propose a simpler solution:
Issue letters of marque for illegal fishing. >

Becomes too easy to pirate legit ships. If there are no survivors there is no other side to the story. >

The 'legit' ships are screwing us over too.  What we need is a moratorium on all fishing so...I don't see this is a bad thing.