A long-term study of a common bottlenose dolphin (Tursiops truncatus) population inhabiting the Gulf of Guayaquil, Ecuador (2°33′ S, 79°20′W), has been carried out for almost 30 years. Similarly, as in other parts of the world, this population is structured socially and spatially in well-defined subunits or communities. Two of these communities, referred to as Posorja and El Morro, have been studied with major intensity in the last 10 years in the western inner estuary, among others to calculate population parameters that allow assessing their viability in time. Calculated parameters include annual abundance, age and sex composition, annual crude birth rate, calf survival, calf production interval, and average annual mortality/emigration. With these parameters and others derived from other better-studied populations, the trend of both subunits was modeled using the software Vortex. Results show that even under an optimistic scenery both communities will be extinct in the short (Posorja) and mid-term (El Morro), if current stressors continue. Most population parameters calculated in both communities show similar values as in populations elsewhere, but a very low calf survival in Posorja and high mortality/emigration ratios in adults, and probably in juveniles in both communities, contribute to this trend. Population deterioration seems to be the result of different human-induced threats such as fisheries, maritime traffic and others still not well assessed, as well as stochastic demographic events. We recommend taking actions in the short term to halt population decline addressing the major causes of mortality affecting these dolphin communities.

中文翻译：

---

厄瓜多尔瓜亚基尔湾两个宽吻海豚群落的灭绝风险迫在眉睫

对居住在厄瓜多尔瓜亚基尔湾（南纬 2°33'，西经 79°20'）的普通宽吻海豚（Tursiops truncatus）种群进行了近 30 年的长期研究。类似地，与世界其他地区一样，这一人口在社会和空间上以明确定义的亚单位或社区构成。其中两个社区，称为 Posorja 和 El Morro，在过去 10 年里在西部内河口进行了大量研究，其中包括计算人口参数，以便及时评估其生存能力。计算的参数包括年丰度、年龄和性别组成、年粗出生率、小牛成活率、小牛生产间隔和平均年死亡率/迁徙。使用这些参数和其他来自其他更深入研究的人群的参数，使用 Vortex 软件对两个亚基的趋势进行建模。结果表明，如果当前的压力继续存在，即使在乐观的情况下，这两个社区也会在短期（Posorja）和中期（El Morro）灭绝。在两个社区计算的大多数种群参数显示出与其他地方种群相似的值，但 Posorja 的小牛存活率非常低，成年和可能在两个社区的幼鱼中的死亡率/移民比率很高，导致了这一趋势。人口恶化似乎是不同的人为威胁的结果，例如渔业、海上交通和其他尚未得到充分评估的威胁，以及随机人口事件。我们建议在短期内采取行动阻止人口下降，解决影响这些海豚社区的主要死亡原因。