Appendix S3. Indian Ocean whale shark database from The ecological connectivity of whale shark aggregations in the Indian Ocean: a photo-identification approach

Genetic and modelling studies suggest that seasonal aggregations of whale sharks (<i>Rhincodon typus</i>) at coastal sites in the tropics may be linked by migration. Here, we used photo-identification data collected by both citizen scientists and researchers to assess the connectedness of five whale shark aggregation sites across the entire Indian Ocean at timescales of up to a decade. We used the semi-automated programme I³S (Individual Interactive Identification System) to compare photographs of the unique natural marking patterns of individual whale sharks collected from aggregations at Mozambique, the Seychelles, the Maldives, Christmas Island (Australia) and Ningaloo Reef (Australia). From a total of 6519 photos, we found no evidence of connectivity of whale shark aggregations at ocean-basin scales within the time frame of the study and evidence for only limited connectivity at regional (100-1000km) scales. A male whale shark photographed in January 2010 at Mozambique was resighted eight months later in the Seychelles and was the only one of 1724 individuals in the database to be photographed at more than one site. On average, 35% of individuals were re-sighted at the same site in more than one year. A Monte Carlo simulation study showed that the power of this photo-ID approach to document patterns of emigration and immigration was strongly dependent on both the number of individuals identified in aggregations and the size of resident populations.

遗传与建模研究表明，热带沿海区域的鲸鲨（*Rhincodon typus*）季节性聚集群可能通过迁徙相互关联。本研究利用公民科学家与科研人员共同采集的照片识别数据，对整个印度洋范围内5个鲸鲨聚集点在长达10年的时间尺度上的连通性进行评估。我们采用半自动化程序I³S（个体交互式识别系统，Individual Interactive Identification System），对采集自莫桑比克、塞舌尔、马尔代夫、澳大利亚圣诞岛以及澳大利亚宁格鲁礁的鲸鲨个体独特天然斑纹照片进行比对。在总计6519张照片中，本研究未发现研究时段内鲸鲨聚集群在大洋盆地尺度上存在连通性的证据，仅在区域尺度（100-1000公里）上发现了有限连通性的相关迹象。2010年1月在莫桑比克拍摄到的一头雄性鲸鲨，于8个月后在塞舌尔被重新观测到，它是该数据库1724头个体中唯一在两个及以上聚集点被拍摄到的个体。平均来看，有35%的个体在多年间于同一聚集点被重新观测到。一项蒙特卡洛模拟研究显示，本照片识别方法用于记录鲸鲨迁出与迁入模式的效能，强烈依赖于聚集点中被识别个体的数量以及定居种群的规模。