It seems to me that these fishnets would have apeared dark on an airial photo, and not light like they do. On the airials it looks like they are lines of clear sand under the water, unlike most of the area where it is covered by sea weed or something.

Couldn't it be pipes. there is a big white area too, maybe there use to be an oilrig there and there use to be oil pipes there, so now there is just clear sand.?