||NGO Oceana has published a new investigative report highlighting four commercial fishing vessels that appeared to turn off their public tracking systems; potentially questionable behavior known as "going dark at sea".While this public tracking system, called the automatic identification system (AIS), was initially designed as a safety mechanism for vessels to avoid collisions at sea, it can also be used to monitor and track vessel movements over time. A ship’s crew may turn off its AIS broadcast for a variety of legitimate reasons, but this behavior may indicate that a vessel is hiding its location and identity to conceal illegal activities like fishing in no-take protected areas or entering another country’s waters without authorization. Using Global Fishing Watch, which provides a never-before-seen view of commercial fishing activity worldwide, Oceana claimed to identify four events where a ship’s AIS device was "possibly turned off".The first saw a Panamanian commercial fishing vessel seemingly disappear on the west side of the Galapagos Marine Reserve, reappearing after 15 days on the east side of the reserve. An Australian commercial fishing vessel appeared to disable its AIS near the Heard Island and McDonald Islands Marine Reserve on ten separate occasions over one year. A Spanish commercial fishing vessel appeared to repeatedly go dark when approaching The Gambia’s national waters over a one-and-a-half-year period.