First of all the seal is quite underexposed so that's the first thing I fixed in Aperture. Then I used Color Efex from Nik software to enhance the seal a bit and bring the details out. I sharpened it (again with a plug in from Nik) and then I used the dodge, burn, contrast and definition tools (in Aperture) to further enhance the photo. Then I made a different crop because to crop as much as you did and expect the photo to survive is a tall order for me. For you information; you should clean your sensor. I counted five sensor spots in this picture.
Cheers,
Remco