Image courtesy of SkyTruth
Arguably the single most destructive human action for the world's oceans, bottom trawling, a practice commonly used to dredge up deep water fish, leaves behind a trail of destruction that can clearly be seen from space. The above image of the Gulf of Mexico, captured by the Landsat satellite in late 1999, shows the sediment trails left behind by individual ships (the bright spots) - a testament to the utter devastation the practice exerts on vast seafloor ecosystems. Les Watling, a zoologist at the University of Hawaii who was interviewed by LiveScience's Andrea Thompson, said that bottom trawling drags the equivalent of an area twice the size of the combined lower 48 states each year. The sediment plumes arise as ships drag their nets across the ocean floor, moving rocks, crushing reefs and stirring up various marine organisms.
Watling described these plumes as just the "tip of the iceberg," explaining that most trawling takes place in waters deep enough to mask the plumes from sight. He presented the results of his work at the AAAS meeting in Boston alongside John Amos of SkyTruth, the West Virginia-based remote sensing and digital mapping non-profit group that tracked the plumes.