In northern Canada, the largest carnivore in the world spends 12 hours a day hunting on the sea ice. The Polar Bear is considered a marine mammal due to the fact that it is dependent on the sea ice to hunt and breed. This formidable predator can spot seals from miles around thanks to its powerful sense of smell. It is able to stand motionless near a hole in the sea ice for long hours, waiting for a seal. When one rises to the surface to breathe, it pulls it out of the water with one paw swipe. It hunts around 60 seals a year and its stomach can hold up to 154 lb (70 kg) of meat. Thus it does not waive any prey and makes fat reserves to survive the dearth period when the sea ice melts and disappears in the summer. Today, the sea ice melts earlier and re-forms later in the year, reducing the hunting season and threatening its survival.