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 354

distribution of porpoises by disordering the distribution of fishes, which are the prey of
porpoises.

Conservation Suggestions

Since the ―back and forth‖ movement and genetic communication among the porpoise
groups in the Poyang Lake and Yangtze River main stem may still occur, the groups should
be considered collectively as a uniform unit for conservation.
Bridges and their construction, shipping traffic, and current direction along with its
turbulence, might have affected the presence or movement pattern of porpoises in the Poyang
Lake mouth area. To mitigate these effects we suggest: (1) the local bottom topography under
the bridges should be recovered back to its arenaceous, quagmiry, and adlittoral state;
characteristics of the finless porpoise's favorite habitat (Chen et al., 1997); (2) to reduce the
water vibration and underwater noise the speed of road and water traffic should be restricted,
and whistling (boat and car horns) should be avoided when vehicles cross these bridges and
ships pass along the water channel,; (3) reservoir discharge events (such as from Three-
Gorges Dam), should be tightly regulated to reduce artificially-high river turbulence and
changes in current direction within Poyand Lake's mouth.
Clearly, there are limitations to these data as they were collected over a relatively short
period of time (buoy based-3 months; boat based-two days) and there was a detection range
limit of only 300 m for each probe. We recommend that future studies incorporate year-round
monitoring and a series of probes.

A CKNOWLEDGMENTS

This work was supported by the National Basic Research Program of China
(2007CB411600), the Chinese National Natural Science Foundation (30730018), the Ocean
Park Conservation Foundation of Hong Kong (OPCFHK), the President's Fund of the
Chinese Academy of Sciences, Special Funds for Presidential Scholarships of the Chinese
Academy of Sciences (082Z01), Research and Development Program for New Bio-industry
Initiatives of Japan, and Grant-in-Aid for Scientific Research (B) of Japan (19405005).

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