A lot of folks over on Digg were very skeptical of the existence of the North Pacific Trash Gyre. They want to know: why are there no photos of floating heaps of trash? Why can’t you see the giant trash island the size of Texas on Google Earth?
When I learned of the trash gyre, I was equally skeptical, due to common misconceptions that get perpetuated in mainstream media articles. The most common misconception is that the trash pile is like an island, or a dense pile like this one in San Diego Harbor. It’s not packed in as tight as that – it’s more like a dense collection of tiny floating pieces of plastic, most of which are not on the surface. A big container ship or naval vessel going through there would probably not notice much out of the ordinary – after all, there is some degree of plastic trash floating on the surface all over the world.
To really get a sense of how much plastic is in there, you have to do a trawl, which entails dragging a net with a bucket on the end behind your boat. Here’s a photo of a bongo trawl taken off of southern California. (Credit: Barbeau Lab, SIO) And here’s a photo of what a normal bongo trawl should produce – lots of zooplankton, a few invertebrates, and the occasional small fish.
Now, contrast this with the results of a trawl from the North Pacific Gyre. Here’s the bongo net being hauled up – see how the ocean looks normal? But the contents – plastic, plastic, and more plastic.* (Credit: Algalita Marine Research Foundation). When all that plastic collects somewhere, you get beaches like this one in the NW Hawaiian Islands.
For this reason, the trash gyre would be very, very hard to clean up. The plastic is so small, and so scattered, that it would take high-intensity trawling similar to that for shrimp. And shrimp trawling kills 10 pounds of non-targeted life (sharks, turtles, fish, you name it) for every pound of shrimp gathered. (Yes, Forrest Gump lied to you – for some reason they didn’t want drowned turtles next to Tom Hank’s angelic self.) The mortality caused by trying to remove all the trash in the gyre would probably be similar. We’re just going to have to live with it and try to prevent it from getting any bigger.
*Note: some of these results are from manta trawls intead of bongos – it’s just a differently shaped net.