Abstract Globally, hawksbill turtles (Eretmochelys imbricata) are listed as Critically Endangered, the cause of which is largely attributed to excessive historical take by the tortoiseshell industry. Yet few long-term data analyses describing population trend or survivorship exist. Here we analyse a long-term dataset for a globally significant western Pacific E. imbricata nesting population on Milman Island, northern Great Barrier Reef. Three demographic indicators were used: (1) number of egg clutches laid, (2) nester abundance and survival, and (3) the body-size distribution of nesters (curved carapace length, CCL). Models were developed for a time series from the 1990–91 to 2016–17 nesting season that included 21 years of sampling, with predicted trends evaluated against samples from the 2017–18 nesting season. The number of clutches laid and nester abundance rate of decline varied over the study period, but the decline was markedly similar with a 58 and 57% overall reduction, respectively. Annual survival rate was high (0.972, 95% CI = 0.965 to 0.977), but was not estimated separately for all years. Models predicted that the current rate of decline would lead to nesting extirpation by 2036 (95% CI: 2026–2058) and 2032–2037 (95% CI: from 2020 to increasing), for the models of nester abundance and number of eggs laid, respectively; and aligned with the observed values for the test dataset (2017–18 season). The rate of decline of E. imbricata nesting at Milman Island highlights the urgency to understand and mitigate risks faced by this endangered population and more broadly across the western Pacific.

中文翻译：

---

二十八年的衰退：昆士兰东北部濒危玳瑁（Eretmochelys imbricata）的筑巢人口统计和轨迹

摘要 在全球范围内，玳瑁 (Eretmochelys imbricata) 被列为极度濒危物种，其原因在很大程度上归因于玳瑁产业对历史的过度利用。然而，很少有描述人口趋势或存活率的长期数据分析存在。在这里，我们分析了大堡礁北部米尔曼岛上全球重要的西太平洋 E. imbricata 筑巢种群的长期数据集。使用了三个人口统计指标：（1）产卵数，（2）巢穴丰度和存活率，以及（3）巢穴的体型分布（弯曲的甲壳长度，CCL）。模型是为 1990-91 到 2016-17 筑巢季节的时间序列开发的，其中包括 21 年的采样，并根据 2017-18 筑巢季节的样本评估了预测趋势。在整个研究期间，产窝数量和窝巢丰度下降率各不相同，但下降幅度明显相似，总体下降幅度分别为 58% 和 57%。年生存率较高（0.972，95% CI = 0.965 至 0.977），但并未对所有年份进行单独估计。模型预测，到 2036 年（95% CI：2026-2058）和 2032-2037（95% CI：从 2020 年到增加），当前的下降速度将导致筑巢消失，对于筑巢丰度和产卵数量的模型， 分别; 并与测试数据集（2017-18 赛季）的观测值保持一致。在米尔曼岛筑巢的 E. imbricata 数量下降的速度凸显了了解和减轻这一濒危种群以及更广泛的整个西太平洋地区面临的风险的紧迫性。