Looks like they were definitely keyed in on the vertical structure of the bridge pillars, as there doesn't seem to be any cover in or around the base of them.
I'm curious though, Roy, as to the pillars image on the left side of the screen ... is that a faint image of the pillars on the right side of the screen or a separate set of pillars farther away from the boat than the ones on the right ?? Reason I ask is that the faint images of fish on the pillars on the left side of the screen do not all look to be in the same position as those on the right ... it looks as though there are some in the same position, but a greater number look to be near the bottom of the pillars.
And if it is a "ghost" image of the pillars on the right side of the screen ... how does that happen ??