Dulau Violaine, Estrade Vanessa, Fayan Jacques
GLOBICE-Reunion, Grand Bois, Saint Pierre, Reunion Island, France.
BNOI-ONCFS, Parc de la Providence, Saint-Denis, Reunion Island, France.
PLoS One. 2017 Jun 22;12(6):e0179780. doi: 10.1371/journal.pone.0179780. eCollection 2017.
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' < 0.01), while females showed a random temporary emigration (γ") of 0.10, suggesting that a small proportion of females was outside the survey area during each primary sampling period. Sex-specific temporary migration patterns were consistent with movement and residency patterns observed in other areas. The Robust Design approach provided an appropriate sampling scheme for deriving island-associated population parameters, while allowing to restrict survey effort both spatially (i.e. west coast only) and temporally (five months per year). Although abundance and survival were stable over the six years, the small population size of fewer than 100 individuals suggested that this population is highly vulnerable. Priority should be given to reducing any potential impact of human activity on the population and its habitat.
2009年至2014年期间，在印度洋留尼汪岛（东经55°33′/南纬21°07′）附近海域开展了印度-太平洋宽吻海豚的照片识别调查。应用稳健设计模型来得出最可靠的种群数量和存活率估计值，同时考虑到从调查区域（西海岸）的临时迁出情况。抽样方案包括在研究的每年中设置一个为期五个月（6月至10月）的抽样期。基于0.096的随机临时迁出率（γ"）和0.70（标准误=0.03）的独特个体比例，留尼汪岛的总体种群规模估计为72头（标准误=6.17，95%置信区间=61-85）。年存活率为0.93（±0.018标准误，95%置信区间=0.886-0.958），且随时间和性别保持恒定。考虑性别分组的模型表明，雄性和雌性之间存在不同的移动模式。雄性的临时迁出率为零或近似为零（γ" = γ' < 0.01），而雌性的随机临时迁出率（γ"）为0.10，这表明在每个主要抽样期，有一小部分雌性不在调查区域内。特定性别的临时迁徙模式与在其他区域观察到的移动和居留模式一致。稳健设计方法提供了一种合适的抽样方案，用于推导与岛屿相关的种群参数，同时允许在空间上（即仅西海岸）和时间上（每年五个月）限制调查工作量。尽管在这六年中种群数量和存活率保持稳定，但不到100头的小种群规模表明该种群高度脆弱。应优先减少人类活动对该种群及其栖息地的任何潜在影响。
