Emesis: It doesn't. But it is interesting if you already know what bottom trawling is: scraping clean an entire ecosystem just to get to one product---er, fish. It would be the equivalent of burning down a village to get the floor tile of its residents. It is the kind of thing that is done because it has always been done and is only now being questioned now that the majority of the large fish in the ocean are critically overfished. National Geographic's website is a good unbiased source for more information. The way we are treating the oceans is so shocking it only continues because we can't see it happening. So any visual indicator is good.