Long-term real-time monitoring of Ganges river dolphins using array of hydrophones

为了了解恒河海豚在长时间跨度上的声学行为，本项目利用6-水听器阵列系统对恒河海豚进行了3个季节的枯水期4-6个月的年度长期实时监测。研究对象为生活在恒河水系卡纳瓦斯(上游)至纳罗拉(下游)10公里范围内的15-18只恒河海豚(成体和幼体)。在监测中，系统根据在阵列的每个水听器上接收到的海豚的高频回声定位点击，计算出每只海豚在观察区周围的实时水下三维位置。它还可以将实时的三维位置数据通过码分多址调制解调器传输到主机服务器。任何装有适当查看器程序的PC都可以访问主机，并在整个监控期间监控海豚的实时活动。通过对每个监测阶段的离线数据分析，揭示了恒河海豚在恶劣的自然条件下生存的行为策略。这对保护恒河海豚很有帮助。

For understanding the Ganges river dolphin's acoustic behavior over a long-time span, the annual long-term real-time monitoring for 4-6 months in the dry season using 6-hydrophone array system has been conducted for 3 seasons in this program. 15-18 Ganges river dolphins(adults and calves) that inhabit the 10 km stretch from Karnavas(upstream) to Narora(downstream) in Ganges river system were subjected to the study. In the monitoring, based on the dolphin's high frequency echolocation clicks received on each hydrophone of the array, the system calculates each dolphin's real-time underwater 3-D location around the observation area. It can as well transmit the real-time 3-D location data to the host server by CDMA modem. Any PC with an appropriate viewer program can access the host and monitor the dolphins' real-time movements during the entire monitoring period. Following off-line data analysis of each monitoring phase, the Ganges river dolphin's behavioral strategy for surviving in tough natural conditions has been revealed. This helps in the Ganges river dolphins conservation.