Blue sharks are found worldwide in temperate and tropical oceans, most often in the offshore surface waters. They are found throughout Canada's Pacific waters, and in Atlantic Canada they are found in almost all waters, from northeastern Newfoundland southward, including the Gulf of St. Lawrence and the Bay of Fundy. Blue sharks are most commonly encountered offshore between the surface and 350 m.

Blue sharks are long and slender, reaching 3.8 m in length, with distinctive blue coloration on their backs and sides. Their eyes are large and have a lower eyelid that is able to open and close. They have long pointed snouts and long pectoral fins. Maturity is reached between ages 4-6 and maximum age is between 16-20 years.