Estimated detection distance of a baiji's (Chinese river dolphin, Lipotes vexillifer) whistles using a passive acoustic survey method.
Source levels and phonation intervals of whistles produced by a free-ranging baiji (Chinese river dolphin) were measured in the seminatural reserve of Shishou in Hubei, China. A total of 43 whistles were recorded over 12 recording sessions. The mean dominant frequency (the frequency at the highest energy) was 5.7 kHz (s.d. = 0.67). The calculated source level was 143.2 dB rms re 1 microPa (s.d. = 5.8). Most phonation intervals were shorter than 460 s, and the average interval was 205 s (s.d. = 254). Theoretical detection range of baiji's whistle was 6600 m at the present study site, but it could reduce a couple of hundred meters in practical noisy situation in the Yangtze River. Sporadic phonation (205 s interval on average) with relatively faint signal of baiji was considered to be difficult to be detected by a towing hydrophone system. Stationed monitoring or slow speed towing of hydrophones along the river current is recommended.
Wang
Kexiong
K
Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, People's Republic of China.
Wang
Ding
D
Akamatsu
Tomonari
T
Fujita
Kaoru
K
Shiraki
Rika
R
D000162:Acoustics / Q000295:instrumentation*; D000818:Animals; D002681:China; D004289:Dolphins; D004777:Environment; D005260:Female; D009622:Noise; D045483:Rivers; D012767:Ships; D014828:Vocalization, Animal