Marine Environment affected by rise in Shipping Traffic.
Global trade is driving huge growth in ship traffic in the world's oceans, with four times as many ships plying now than in 1992.
Evidence was also found of illegal fishing in protected marine areas, such as ships plying in waters around the Kerguelen Islands Marine Reserve in the Southern Indian Ocean.
Cargo shipping accounts for much of the growth. The biggest increase in ship traffic between 1992 and 2012 was along popular shipping lanes in the Indian Ocean and the Chinese seas.
The Pacific Ocean saw a rise in ship traffic after 2008, especially near China. The Mediterranean, the Red Sea and the West Coast of the United States also saw big increases. In contrast, commercial piracy off Somalia's coast has triggered a near halt in shipping there since 2006.
Satellite altimetry data are being used to count ships at sea between 1992 and 2012. Satellite altimeters are instruments that measure sea surface height in very fine detail. The ocean's hills and valleys provide clues as to what lies beneath, such as global currents and seafloor topography.
These findings provide an independent check to the Automatic Identification System, which tracks vessels using GPS and other instruments. Ships can turn off the receivers that track their movements if they want, and small vessels aren't required to report their location.
The data will also provide scientists with insights into the patterns of ship traffic, and the traffic's effect on the environment.
Human activities such as shipping traffic in the ocean have heavy impact on the marine environment. These effects include air pollution, ocean noise, oil spills and spread of invasive species.