Photo by Brian Skerry ; A harp seal pup about 14-days old makes it first swim in the icy waters (29-degrees F) of Canada's Gulf of St. Lawrence. Harp seal pups continue to be hunted in Canada, where hunters target these animals just after they shed their white coat at an age of about 17 days. Conservation photography may be a discipline you've never heard of. While the foundations have been around since the beginning of photography itself -- using images to make people aware of, and respond to, environmental issues -- the genre has only been given a name in the last few years. And yet, it is one area in which some of the best photographers in the world are spending their energies, using the power of photos to conserve natural spaces. Meet seven of the best in the business, and see their stunning shots.