关键词: 中华白海豚, 江豚, 分布格局, 遇见率, 家域

Abstract: The Beibuwan Gulf represents a crucial distribution area of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides)in China. However,the systematic research on the distribution pattern and its tempo-spatial variation of these two species in this waters is still deficient,and it is still unclear whether they are overlapped with each other. In 2003 - 2004 and 2011 - 2012 surveys,we conducted boat-based surveys twice at Shatian, Beibu Gulf with 4 876.8 km survey route in total,and collected the spatial distribution data of both species. Only humpback dolphins were sighted in 2003 -2004,whereas both species were sighted in 2011 - 2012. Compared with the result of April and May 2003 - 2004,the encounter rate of humpback dolphins in April-May,2011 was significantly higher (0. 152 vs 0. 028 individuals/ km survey line). The Minimum convex polygon (MCP),95% Fixed kerne (FK)home range and 50% FK core range of Indo-Pacific humpback dolphins were 162.6 km² ,271. 35 km² and 56.78km²,respectively. From 2003 -2004 to 2011 -2012,the 50% FK core range enlarged and moved eastward. The MCP,95% FK home range and 50% FK core range of finless porpoises were 97.21 km² ,318. 72 km² and 38. 18km² respectively. The finless porpoise is mainly distributed in the periphery of the distribution area of Indo-Pacific humpback dolphins,and a small part of distribution area of both species is overlapped. Based on the analysis of some possible factors,it was suggested that finless porpoises possibly migrate inshore-toward seasonally,whereas Indo-Pacific humpback dolphins have preference to the estuary area,which might have led to the different distribution pattern of both species.

Key words: Distribution pattern, Encounter rate, Finless porpoises (Neophocaena phocaenoides), Home range, IndoPacific humpback dolphins (Sousa chinensis)