East Asian Finless Porpoise
The East Asian finless porpoise (Neophocaena sunameri) is a captivating cetacean species native to the coastal waters of the East China Sea, Yellow Sea, and the seas surrounding Japan. It belongs to the family of porpoises, distinguished by their lack of a dorsal fin, which gives them their name.
Physical Description
East Asian finless porpoises are relatively small marine mammals, typically reaching lengths of up to 2.27 meters (7 feet 5 inches) and weighing as much as 72 kilograms (159 pounds). Notably, the coloration of these porpoises varies by subspecies. Newborn calves from the central and eastern regions are generally black with grey around the dorsal ridge, transitioning to a full grey over several months. Alternatively, calves from the western subspecies are born a light creamy grey and darken with age.
Habitat and Distribution
These porpoises inhabit shallow, coastal environments, often found in waters no deeper than 50 meters (160 feet). They are commonly located near shores with sandy or soft seabeds, as well as in estuaries and mangrove swamps. Despite their preference for shallow waters, they have occasionally been spotted as far as 135 kilometers (84 miles) offshore, still in shallow zones.
Their range encompasses the coastal areas off mainland China, extending south to the Penghu Islands. The northernmost limit of their habitat is around the Matsu Islands, where the local population appears physically smaller than their relatives in other regions.
Taxonomy and Evolution
The East Asian finless porpoise is part of the genus Neophocaena, making it one of the basal living members of the porpoise family. Recent genetic studies have highlighted the evolutionary divergence between the East Asian finless porpoise and the Yangtze finless porpoise, indicating that they are separate species. This genetic distinction underscores the need for tailored conservation strategies for each species.
Conservation Status
As with many marine species, the East Asian finless porpoise faces threats from human activities. Their coastal habitats are vulnerable to pollution, overfishing, and increased boat traffic. Conservation efforts are essential to protect this species from further decline, requiring international cooperation and local engagement.