Try this: http://www.lysator.liu.se/~kand/caustics/ for caustics instead of procedurals. Your method looks a bit unreal due to black dots in some places, I would suggest tweaking color ramps. Maybe you should scale texture, ripples over whale on surface are much larger than projected caustics elements.
A whale won’t swim in shallow water like yours, only other crit except of the caustics would be the lines you sculpted on its belly. I looks euhm sculpted…
I think if you back away from the whale it might give the water a greater depth-feel. Plus, it may get a more-documentary-realistic camera feel if you’re not right on top of it.
Pretty good so far. You definitely need to tweak the caustics though. If you want to do them procedurally, I’d suggest increasing the size and then adding another texture (distorted noise?) to warp it. Play around with it.
Also on that subject, if I’m not mistaken, there would be caustics on the seabed as well.