text: Could GFW ‘train’ its computers to recognise the exact manoeuvres a vessel undertakes while it is setting, and hauling, a longline – in order to see if setting was really happening at night?
  “We did something pretty unprecedented, we trained machines to see if they could tell detailed vessel behaviour.
  Until now we could really only tell if vessel was fishing or not fishing, we could not go a level deeper and determine when they set a line, when they haul it in…now we can..” He adds that these same techniques can perhaps in future even identify the species vessels are targeting.
  The intermediate period is pretty fast as the vessel returns to the start of the set, however it’s a bit slower, likely because the slightly slower speed is more fuel efficient, and then the haul is slower andpretty variable.
  The GFW team used data for 2017, received from more than 60 orbiting satellites, corresponding to more than 300 pelagic longline vessels operating in the southern Atlantic, Indian and Pacific Oceans (south of 25/30degs of latitude depending on area concerned) to train a model of longline setting.
  Studies have shown that bird bycatch rates suddenly increase one hour before sunrise, at nautical dawn, when birds start feeding, indicating that for night setting to be effective, the entire set must start after nautical dusk and end before nautical dawn.