This is good research but the hinting that turning off AIS is from ill intent with fishing is not universally true. I have lived and worked on Alaskan fishing boats on and off for a while now. Most people turn off AIS or don't run it at all so they don't reveal their fishing spots to other vessels.
This is going to be an ongoing hurdle for most fisheries if more complete tracking is the goal.
This is going to be an ongoing hurdle for most fisheries if more complete tracking is the goal.