Dogfish sharks are small, common members of the shark family found across a wide range of marine environments, from shallow coastal bays to the deep slopes of the continental shelf. Understanding their habitat requires looking closely at the specific types of dogfish and the diverse conditions they seek out globally.
Identifying the Dogfish Species
The name “dogfish shark” refers to several species, most commonly the Spiny Dogfish (Squalus acanthias) and the Smooth Dogfish (Mustelus canis). The Spiny Dogfish is the most widespread and abundant species, characterized by a spine in front of each of its two dorsal fins. The Smooth Dogfish lacks these dorsal spines and is found primarily in the Western Atlantic Ocean. Since the Spiny Dogfish is found across nearly all temperate seas, it serves as the primary focus for discussing the habitat and range of this group.
Global Geographical Range
The Spiny Dogfish has a vast, circumboreal distribution, found in the temperate and subarctic zones of both the Northern and Southern Hemispheres. In the Atlantic Ocean, populations range along the coasts of North America, from Greenland and Labrador down to Florida, and are abundant between Nova Scotia and Cape Hatteras. The Eastern Atlantic population stretches from Iceland and the Murmansk Coast of Russia down to South Africa, including the Mediterranean and Black Seas.
The species also occupies a significant range in the Pacific Ocean. They occur along the North American coast from the Bering Sea down to Chile, and across the western Pacific, they extend from the Bering Sea to Japan, south to New Zealand and Australia. While Northern Hemisphere populations are dominant, dogfish are also found off the coasts of South America, South Africa, and New Zealand. These populations across major ocean basins are not believed to mix significantly, suggesting distinct regional groups.
Specific Environmental Preferences
Dogfish sharks are generally bottom-dwelling (demersal) species that prefer to live on or near the seabed of continental shelves and slopes. They thrive in cool to temperate waters, typically favoring a temperature range between 44°F and 59°F (7°C and 15°C). This preference for cooler conditions influences their geographic distribution and movements.
Their vertical habitat range is broad, extending from shallow coastal bays and the intertidal zone to the deep ocean floor. Dogfish are commonly found over the continental shelf at depths between 160 and 490 feet, but they have been recorded exceeding 2,950 feet (900 meters). Although they prefer full-strength seawater, Spiny Dogfish can tolerate brackish water and occasionally enter estuaries, but they cannot survive in freshwater.
Seasonal Movements and Migration
Dogfish are highly migratory, with movements driven by seasonal changes in water temperature and reproductive cycles. They make significant latitudinal migrations, traveling north in the spring and summer to find cooler feeding grounds and moving south in the fall and winter. This allows them to remain within their preferred temperature range throughout the year.
Dogfish also migrate between inshore and offshore waters based on the season. During colder months, they typically move to deeper, more stable offshore waters. As waters warm in the spring and summer, they move inshore or into shallower waters, which is often associated with feeding and breeding activities. These migrations typically involve large, dense schools, often segregated by the size and sex of the individuals.