China’s new Personal Information Protection Law, which came into effect at the start of the month, has sent international ship tracking organisations into a spin.

The data law has seen ships disappear from some tracking services when they enter Chinese waters.

“All of a sudden we do not know when ships are leaving and from where, and we also don’t have the full picture on port congestion which AIS offers us,” Anastassis Touros, AIS network team leader at MarineTraffic, one of the world’s top vessel tracking firms, told Reuters.

Over the past three weeks, the level of terrestrial shipping data across all Chinese waters has dropped by an estimated 90% according to VesselsValue, which has warned that the new Chinese law could cause significant challenges concerning ocean supply chain visibility.

An employee at Beijing-based AIS data provider Elane told Reuters that all dealings with foreign entities were recently halted