DETECTION OF YANGTZE FINLESS PORPOISES IN THE POYANG LAKE MOUTH AREA VIA PASSIVE ACOUSTIC DATA-LOGGERS - Biology, Evolution and Conservation of River Dolphins Within South America and Asia - page 350

at Station C was displayed by both the diurnal presence ratio (per hour) in Figure 5a and by
the day presence ratio (per day) in Figure 6b. The number of ships detected by the A-tag in
(per hour) over the entire observation period is shown in Figure 5B. Figure 6A shows the flux
and direction of water current measured daily over the entire observation period.
Figure 4. (a) Average number of porpoises per unit time (1 minute) at Stations 0, 1, and 2, to which
swimming direction could be determined. Positive bars indicate animals swimming upstream to the
Poyang Lake, negative bars indicate swimming downstream to the Yangtze River. (b) Average number
of porpoises detected per unit time (1 minute) at the three stations. Standard deviations (S.D.) are also
included.