The drawing is by John Tubbs, as shown the darkest value are the frontground. But the focus point are the person in the boat with the 2nd darkest value in the center of the drawing.  The artist also make the fishes a light value which show there’s light coming from the right side, which had created some dark value on the left side, which seem to a more closer ground to the main character with leaving the right side background the lightest.