being a pelagic species, the shark's habitat consists of open ocean areas, from the surface to 350 metres (1,148 feet) in depth. they prefer cooler water ranging from 7 to 16 °c (45-61 °f) in temperature. they are known to swim in water with the temperature of 21 °c (70 °f) or greater. when in the tropics, the shark usually swims to deeper water with cooler temperatures. this is common in the tropical indian ocean, where the majority of blue sharks are found at depths of 80–220 metres (263–722 feet), where water temperatures range from 12-25 °c (54-77 °f). in the pacific, at latitudes between 20°n and 50°n, they are known to migrate to higher latitudes during the summer and lower latitudes during the winter. their populations remain constant throughout the year between 20°n and 20°s latitude.