Every vessel on the ocean broadcasts its identity and location
using the automatic identification system (AIS), which is mostly
used to prevent ships from colliding. These days it can also be
used to track ship locations, as most AIS data is relayed through
satellites. If you want to hide on the sea, the first thing you do
is make your vessel "dark" by turning off your AIS broadcasts.
What's interesting about pirate fishing vessels, however, is that
they need to rendezvous with legitimate reefers if they want to get
paid for their catch.
To find the pirates, Amos told Ars, he and Bergman needed to look
for odd patterns in the behavior of reefers. The group partnered
with Global Fishing Watch to work on mapping satellite AIS data,
and those patterns began to emerge. "Often with reefers they come
to a halt in the middle of the ocean," Amos said. "We don’t see
other broadcasting vessels, but we can be confident based on what
that ship is doing that they must be rendezvousing with dark
I guess this counts as a “big data” application...