Porpoises are small marine mammals closely related to whales and dolphins. They are typically smaller and stockier than dolphins. A distinguishing physical trait is their spade-shaped teeth, contrasting with the cone-shaped teeth found in dolphins. Porpoises also generally lack the prominent beak seen in many dolphin species, instead having a more rounded head, and their dorsal fin is notably triangular rather than curved.
Global Presence
Porpoises inhabit a wide array of marine environments across the globe, with widespread but often localized distribution. These species are found in various oceans and coastal regions, from temperate to sub-Arctic waters in both the Northern and Southern Hemispheres. While some species prefer open ocean, many are commonly found in shallower, nearshore habitats.
Specific Species and Their Homes
Several porpoise species have specific geographical ranges and preferred environments.
The Harbour Porpoise inhabits cooler coastal waters of the North Atlantic, North Pacific, and the Black Sea. It is frequently found in bays, estuaries, and fjords, typically in waters less than 650 feet deep, though it can venture offshore.
Dall’s Porpoise primarily occupies the cold temperate and subarctic waters of the North Pacific Ocean. Its range stretches from Japan across the North Pacific Rim to Baja California, including areas like the Gulf of Alaska, Bering Sea, and Sea of Japan. While often found in deep, pelagic waters, they also occur in cooler, glacier-fed inshore areas like those in Alaska.
The Vaquita is an exceptionally rare and critically endangered species found exclusively in the shallow lagoons of the northern Gulf of California, Mexico, near the mouth of the Colorado River and San Felipe.
Finless Porpoises comprise subspecies with distinct ranges within Indo-Pacific coastal waters. The Indo-Pacific finless porpoise spans from the Persian Gulf east to the Taiwan Strait and south to Indonesia. The Yangtze finless porpoise, a freshwater subspecies, is found only within the Yangtze River basin in China, including specific sections of the main river and associated lakes like Poyang and Dongting.
Burmeister’s Porpoise is found along the coastal waters of South America. Its distribution includes the Pacific coast, extending north into Peru, and the Atlantic coast, from southern Brazil southwards around Tierra del Fuego and including the Falkland Islands. These porpoises prefer shallow waters, typically less than 150 meters deep, and are often seen in rivers and estuaries.
The Spectacled Porpoise has a circumpolar distribution across the Southern Hemisphere. This poorly studied species is found in cool temperate, sub-Antarctic, and Antarctic waters of the Atlantic, Indian, and Pacific Oceans. Sightings and strandings indicate their presence near offshore islands and sometimes in the open ocean.
Habitat Characteristics
Many species favor shallow coastal waters, bays, estuaries, and fjords, which provide abundant food. These areas typically have depths ranging from a few meters to around 200 meters, though some species may venture into deeper offshore regions. Most porpoise species thrive in temperate to cold water temperatures, with some, like the Dall’s Porpoise, preferring waters colder than 18°C. Proximity to shorelines often correlates with the availability of schooling fish, squid, and crustaceans, their primary diet. Coastal preferences offer protection but also make porpoises vulnerable to human activities.