Composition in teh last is by far the best in my opinion, this is a great image for both the technical side of things but also has some arty-ness too it, the inclusion of the bark and the speck of green works well, the angle perfectly shows the fins off, I definitely could not do it better
The first has artistic merit, but comes across very flat due to the straight on composition.
The second, its been done before Colin
good technical coverage but I know you could spice that up with a bit of angle or a diagonal composition to give it a more dynamic feel.