It isn't possible, you're talking about hundreds of countries, across international waters, and some level of complicity from various authorities. Technology can only help when it has cooperation. The human factor is often the hardest part of technology solutions.

This could be easily scanned by satellites, although I have no idea what's more cost-effective.

It takes a long time to bring back those lines and to load up the catch.

Time to pass a law to force simplydt to wear a stiff leather collar that administers a painful electric shock every 30 seconds. Of course, although possible, this won't happen any time soon.