Miller, 1918 - Baiji
Distinctive Characteristics
Outside of China, very little was known of the baiji's biology until recently. These animals are moderately robust, with long, slightly upturned beaks, rounded melons, low triangular dorsal fins (set about two-thirds of the way back from the snout tip), and broad rounded flippers. The eyes are small, compared to those of oceanic dolphins, but not as small as those of Platanista sp.
Baiji, or Chinese river dolphins, are predominantly dark bluish grey above and light grey to white below. There are light brushings on the side of the face and the side of the tail stock.
Each tooth row contains 31 to 38 conical teeth.
Can be confused with
The only other small cetacean in the baiji's range is the finless porpoise, which can be readily distinguished by its darker coloration and absence of a dorsal fin.
Size
Male baiji reach sizes of 2.3 m and 135 kg, and females reach 2.6 m and over 240 kg. Apparently, newborn baiji are less than 95 cm in length.
Geographical Distribution
The baiji is found only in the middle and lower reaches of the Yangtze River in China. Baiji may occasionally enter large lakes during intense flooding. The range was formerly broader.
Biology and Behaviour
Groups of 2 to 6 baiji are most commonly seen, but aggregations of up to 13 animals sometimes form. These dolphins are generally shy of boats, and their surfacings are shallow, often exposing only the top of the head, dorsal fin, and a small part of the back.
The peak calving season appears to be February to April.
A large variety of fish species make up the diet of the baiji.
Exploitation
With the possible exception of the vaquita, this is the most endangered of all cetaceans. The major source of mortality for baiji appears to be incidental catches in fishing gear, especially the so-called “rolling hooks” that are used to snag fish along the bottom of the Yangtze. Other threats include vessel collisions and disturbance, pollution, construction of dams, overfishing of prey species, and general modification of habitat through various human activities. Although China has declared the baiji a “Protected Animal of the First Order,” there is still much uncertainty about the future of this species.
IUCN Status
Endangered.