As temperatures hit minus 60 food becomes scarce, and animals such as foxes and hares shed their colourful coats to camouflage themselves in the snow. The end of winter heralds one of the world's greatest feeding frenzies as large ocean predators target the millions of fish who have found refuge in the Gulf of Alaska.

Summer has arrived in Alaska. Free of ice, rivers and streams can flow again. This sets the scene for one of the world's greatest migrations, the Alaskan salmon run.