[glatt]

I'm not a fisherman, so I don't know.

Perhaps the light in these images is a measure of light and not electricity. Perhaps much of the light from these fishing boats is being reflected up into the sky, and that isn't happening as much on the land, where dark colored pavement, dirt and vegetation absorbs much of the light from street lights.

When you shine a light from a high angle into the water, some penetrates the water, and some bounces off the surface like a mirror. Perhaps these fishing boats are, in effect, aiming their lights down into the ocean at the same time they are aiming them up into the lenses of the cameras in the satellites.