Identifying key demographic parameters of a small island–associated population of Indo-Pacific bottlenose dolphins (Reunion, Indian Ocean)

Photo-identification surveys of Indo-Pacific bottlenose dolphins were conducted from 2009 to 2014 off Reunion Island (55°E33’/21°S07’), in the Indian Ocean. Robust Design models were applied to produce the most reliable estimate of population abundance and survival rate, while accounting for temporary emigration from the survey area (west coast). The sampling scheme consisted of a five-month (June–October) sampling period in each year of the study. The overall population size at Reunion was estimated to be 72 individuals (SE = 6.17, 95%CI = 61–85), based on a random temporary emigration (γ”) of 0.096 and a proportion of 0.70 (SE = 0.03) distinct individuals. The annual survival rate was 0.93 (±0.018 SE, 95%CI = 0.886–0.958) and was constant over time and between sexes. Models considering gender groups indicated different movement patterns between males and females. Males showed null or quasi-null temporary emigration (γ” = γ’

本研究于2009年至2014年间，在印度洋留尼旺岛（55°33′E/21°07′S）周边海域开展了印太瓶鼻海豚（Indo-Pacific bottlenose dolphin）的照片识别调查。研究采用稳健设计模型（Robust Design models），在纳入调查区域（西海岸）临时迁出效应的前提下，对种群丰度与存活率进行了最可靠的估算。本次研究的采样方案为：每年设置为期5个月（6月至10月）的采样周期。基于0.096的随机临时迁出率（γ"）与0.70的独特个体占比（标准误（Standard Error, SE）=0.03），留尼旺岛海域的种群总规模估算为72头（标准误（Standard Error, SE）=6.17，95%置信区间（95% Confidence Interval, 95%CI）=61–85）。年存活率估算为0.93（标准误（Standard Error, SE）±0.018，95%置信区间（95% Confidence Interval, 95%CI）=0.886–0.958），且在时间维度与性别间均保持恒定。区分性别分组的模型结果显示，雌雄个体间存在不同的移动模式：雄性个体的临时迁出率为零或近似为零（γ"=γ’）