The Black Fish are a marine conservation organisation who use UAVs to help stop illegal fishing. The idea of using drones/UAVs allow them to very cost effectively monitor fishing boats and look out for illegal drift nets at a fraction of the cost it would otherwise cost. This also massively increases the deterrent factor much more than before as fishermen know without any warning they could be caught on camera.
The drones have been used in the Mediterranean since 2013 to collect evidence of illegal driftnet use. Here’s a great video created by theblackfish.org which shows the work they’ve been doing with drones for the conservation effort.