The blue shark, Prionace glauca, is a highly migratory and widely distributed species of shark. This pelagic shark is recognized by its slender body and distinctive indigo blue coloration, fading to bright blue on its sides and white underneath. The blue shark’s extensive range underscores its adaptability to diverse marine environments across the globe.
Global Ocean Distribution
Blue sharks are found across the world’s major oceans, including the Atlantic, Pacific, and Indian Oceans. They inhabit both temperate and tropical waters, with a broad latitudinal range extending from approximately 60° North to 50° South. These sharks are present off the coasts of every continent except Antarctica.
In the Atlantic Ocean, blue sharks range from Newfoundland and the Gulf of St. Lawrence down to Argentina in the western Atlantic. Their eastern Atlantic distribution spans from Norway to South Africa, encompassing the Mediterranean Sea. They are common in Canadian waters, including off Nova Scotia and Newfoundland during warmer months.
In the Pacific, concentrations occur between 20° and 50° North latitude, though this fluctuates seasonally. Their presence in the eastern Pacific extends from the Gulf of Alaska down to Chile. In the Indian Ocean, blue sharks are found from East Africa to Indonesia, Japan, Australia, New Caledonia, and New Zealand. They are present throughout Australian pelagic waters, excluding areas like the eastern Arafura Sea.
Habitat Preferences
Blue sharks inhabit open ocean (pelagic) environments, remaining away from coastal areas. They may occasionally venture closer to shore in temperate regions, particularly where the continental shelf is narrow or around oceanic islands. They are found from the surface down to depths of several hundred meters, and as deep as 1,000 meters.
Their preferred water temperatures range between 12°C and 20°C, though they tolerate a wider range from 3.9°C to 31°C. Blue sharks often undertake daily vertical migrations, staying around 30 to 40 meters deep during the day and moving to deeper waters at night. In tropical waters, they occupy greater depths to find cooler temperatures. This behavior helps them access suitable thermal conditions and follow prey movements throughout the water column.
Extensive Migratory Routes
Blue sharks undertake long-distance, often transoceanic, migrations. These migrations are influenced by seasonal changes in water temperature, the availability of prey, and their reproductive cycles. Their movements facilitate access to optimal feeding grounds and breeding areas across vast stretches of ocean.
Tagging studies reveal blue sharks make trans-Atlantic crossings, moving from New England to South America. In the North Atlantic, a clockwise migratory pattern has been observed. While trans-Pacific migrations do occur, research suggests such movements are less frequent than previously thought, with many individuals exhibiting regional residency. Blue sharks of different life stages and sexes undertake migrations, often exhibiting segregation by age and sex. Some tracked individuals have moved over 28,000 kilometers in nearly three years.