Table 1.

Baiji population counts and estimates based on surveys carried out from 1979 to 1999 (after Zhang et al. 2003). (S, single vessel survey; M, multi-vessel survey; B, observation from riverbank; P, opportunistic photo-identification of individual animals was possible.)

year	survey area	survey method	no. of boats	no. of km surveyed	no. of surveys	no. of baiji sighted	estimated baiji population	reference
1979	Wuhan–Chenglingji	S	1	230	1	19	—	Chen et al. (1980)
1979	Nanjing–Taiyangzhou	S	1	170	2	10	—	Zhou et al. (1980)
1979–1981	Nanjing–Guichi	S	1	250	6	3–6 groups	400	Zhou et al. (1982)
1978–1985	Yichang–Nantong	S	1	1600	9	>20 groups	156	Lin et al. (1985)
1985–1986	Yichang–Jiangyin	M	1+4–6a	1510	2	42 groups	300	Chen & Hua (1989)
1979–1986	Fujiangsha–Hukou	S	1	630	18	78–79	100b	Zhou & Li (1989)
1987–1990	Yichang–Shanghai	M+B	1+4–6a	1669	12	108	200	Chen et al. (1993)
1989–1991	Hukou–Zhenjiang	P	8	500	5	29	120	Zhou et al. (1998)
1991–1996	Xinchang–Wuhan	M	1+4–6a	413	10	42	<100	Wang et al. (1998)
1997–1999	Yichang–Shanghai	M	34, 14, 16	1687	3	21–23	13+	Zhang et al. (2003)

^aone large vessel plus four to six small boats.

^blower reaches only.