VesselTracker's AIS picked up the 21m Spanish pole and line tuna boat 450 miles WSW of Land's End this morning. No doubt there are a number of other Spanish and French tuna boats all searching for tuna in the area. Normally small boats are not picked up by AIS more than 50 miles from the nearest receiver - but in exceptional weather - no wind, a flat sea and fog - AIS can pick boats up over hundreds of miles away!..
The boat is about 180 miles west of the edge of the continental shelf where the bottom in well in excess of 2000 fathoms.