Development of monitoring systems for studying ecology and behavior of bottlenose dolphins-taking aerial pictures of schools using a captive balloon system and recording underwater vocalizations using a sonobuoy system-

印度太平洋宽吻海豚全年都在日本九州天草的沿海水域出没。为了研究海豚的生态和行为，我们开发了监测系统；一个用于拍摄学校航拍照片的气球系统和一个用于记录学校水下声音的声纳浮标系统。气球系统由一个充满氦气的圈闭气球（直径2.5米）、一个悬挂在气球上的视频子系统（2.1公斤）和一个船上的控制子系统组成。从一所学校的图像中获得以下信息1；学校成员的空中行为，地表个体数量的时间变化，学校的配置和个体的空间分布。当使用长焦镜头拍摄一小部分时，母子对与其他母子对区分开来。母幼对与所有个体比例的季节变化表明，主要的分娩季节为春季至秋季。这一制度适用于外鲸类。除了使用这两种系统进行调查外，还尝试了用船上的水虹吸器直接记录发声，从陆地上进行经纬仪跟踪，行为观察和用于个体识别的照片调查。发声记录显示，海豚有时会在几米或200米前搜索。经纬仪跟踪调查澄清了白天沿海岸有规律的运动模式。行为观察表明，在一天中最热的时候，海豚会在有限的区域休息。个体鉴定调查得出的种群规模估计为近200只，死亡率为每年3.4%。

Indo-Pacific bottlenose dolphins are found thoughout a year in the coastal waters of Amakusa, Kyushu, Japan. To study ecology and behavior of the dolphins, monitoring systems have been developed ; a captive balloon system for taking aerial pictures of schools and a sonobuoy system for recording underwater vocalizations from schools.The balloon system consists of a captive balloon(2.5 m in diameter)filled with the helium gas, a video sub-system(2.1 kg)suspended from the balloon and a control sub-system on a boat. The following information was obtained from images of a schoo1 ; aerial behavior of the school members, temporal changes in number of surfacing individuals, configuration of the school and spatial distribution of individuals. Mother-calf pairs were distinguishable from others when a small portion of the school was taken using a telephoto lens. Seasonal changes in ratios of mothercalf pairs to all the individuals suggest the main parturition season of spring to autumn. This system is applicable to outer cetaceans.Tother with surveys using the two systems, direct recordings of vocalizations by a hydrophon from a boat, theodolite tracking from land, behavior observations, and photographic surveys for individual identification were attempted. Vocalization recordings show that the dolphins searched sometimes a few meters ahead or 200 m ahead. Theodolite tracking surveys clarify a regular movement pattrn along the shore in the daytime. Behavior observations suggest that the dolphins take a rest in a limited areas during the heat of the day. Individual identification surveys give estimetes of population size of almost 200 individuals and mortality rate of 3.4% per year.