One chart shows the dramatic drop-off in ship tracking data from China. This could be a sign of a worsening global supply chain crisis – BUSINESS INSIDER

Ships in Chinese waters have vanished from tracking systems the maritime industry uses, a development that could worsen the global supply chain crisis.

The Automatic Identification System (AIS) — which relies on ships to send data to stations along the coastline or via satellites — has witnessed a plunge in the signals it receives in recent weeks.

Data from market intelligence and valuations provider VesselsValue show the number of signals in Chinese waters plunging 85% in under a month — from more than 100,000 a day on October 28 to over 15,000 a day on November 17.

The steep decline comes after China Personal Information Protection Law came into effect on November 1. The new rules regulate how domestic and foreign organizations collect and export the country’s data.