Spiny dogfish are distributed throughout the world. In Canada, they are found off both the Atlantic and Pacific coasts. In the western Atlantic, they range from Newfoundland and Labrador to Florida. In the eastern Pacific, they occur from Alaska to southern California. Spiny dogfish prefer temperate waters and are most common from Nova Scotia to North Carolina in the Atlantic, and in Puget Sound and the Georgia Strait in the Pacific. They are usually found at depths of 50-200 metres, though sometimes as deep as 350 metres.
Spiny dogfish resemble other species of shark, with a pointed snout and a slender, streamlined body. On their dorsal side they have a spine before each of the two triangle-shaped dorsal fins, the first of which is large and the second small. Their tail fin has an upward directed lobe. They are brown or grey on top and white or greyish-white on their underside. Juveniles will have speckles of white on their back and sides. Spiny dogfish can grow to a maximum length of about 1.5 metres. They live 25 to 30 years in the Atlantic, and up to 80 years in the Pacific.
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