Fishing vessels are required to carry a transponder that tracks their movements and allows authorities to monitor their behaviour. But illegal fishers simply switch off the machine, disappearing from the system.

A UK-funded initiative, developed by Satellite Applications Catapult (SAC) and the Pew Charitable Trusts, uses satellite radars to track these “dark targets”. Now, instead of blindly patrolling vast areas of ocean, coastguard vessels use the satellite intelligence to target their search.