Finless Porpoises: Neophocaena phocaenoides, N. asiaeorientalis

Abstract

Finless porpoises are small phocoenids lacking a dorsal fin. Horny tubercles are sprinkled on their dorsal surface and the shape of this area is distinct between two species, Neophocaena phocaenoides and N. asiaeorientalis. They inhabit shallow coastal waters of the Indian and western Pacific Oceans, and in the large river systems, particularly in the Yangtze River where finless porpoises are distributed up to the middle reaches. The border between the two species ranges is in the Taiwan Strait where two species are observed sympatrically. Like other phocoenid species, finless porpoises are relatively short-lived and do not generally occur in large groups. Finless porpoises are considered to be opportunistic feeders. Due to their coastal habitat, finless porpoises are vulnerable to the various human impacts and significant decline has been reported in several populations.