this image is cool, however, is not a very strong example for this challenge. the reason i say this is that in stock photography, subjects are usually larger and more detailed. in this image, it seems that the rocks are the subject and the seals are extra.
Not sure if that is another seal in front or a rock (looks like a rock, tho), but I'd be tempted to crop the bottom up to the start of the rock. The OOF foreground isnt a distraction and the focus moves back to the seals. The colors are good and I like the layers.
I wonder if this is really close enough to serve: sure it shows location, but there is nothing specific about that location. There are strong elements I really like in it - the texture and depth of the rocks, the poses of the seals - but as successful stock: hell, I don't know.
Nice shot but you composition is too centered. Try cropping just below the green rock you don't need all of the forground. It will make your photo much more interesting and the seal will be more prominent.