I saw a whale as well! Thought it might have been an attempt at "Jonah and the whale" and then I took another look at the title... I think the tail is meant to be the tail of the mermaid, and the white is the body... maybe on a rock?
Thanks for the puzzle! Took me a bit to see it, too, but i think I got it: her fins in the back are dark, her body dives down and forward to the left, with her face in white above the water again looking straight at us. The single dots are her mouth and one eye, the other eye is the last dot of the four in column 15.
Hello puzzlers, it's the author here. I didn't realise making this that it would not be as clear as I thought it was. The image I am trying to depict is that of a mermaid on the waters surface with only a small part of her body submerged.
Just like Rinko said, they got the idea. Sorry if it came out a bit too abstract.