Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.
Integr Zool. 2021 Jul;16(4):538-547. doi: 10.1111/1749-4877.12523. Epub 2021 Mar 14.
The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), a critically endangered species, is the only cetacean species in the Yangtze River following the functional extinction of baiji (Lipotes vexillifer). To inform conservation actions, two important questions need to be addressed: what is the threshold value of survival rate, and what is the threshold value of population size? We calculate the instantaneous rate of population increase ( ) for the Yangtze finless porpoise for various combinations of the calf and the non-calf survival rates. We also test the probability of extinction for different minimum carrying capacities for 100 and 500 years using a stable population model. The threshold value of the non-calf survival rate is never lower than 0.869, but current estimates from field data have been far below this threshold. Our model based on extinction probability and carrying capacity suggests that the threshold for the population size to persist 100 years required 113 animals, and 472 animals are required to persist 500 years. Therefore, we recommend establishing an ex situ reserve network to guarantee the minimum 100-year carrying capacity. To ensure the long-term population viability, we suggest establishing two in situ reserve zones in two lakes and their surrounding reserves to meet a minimum 500-year carrying capacity. In addition, measures to avoid further habitat fragmentation should be priority.
长江江豚（Neophocaena asiaeorientalis asiaeorientalis），一种极度濒危物种，是继白鱀豚（Lipotes vexillifer）功能性灭绝后长江中唯一的鲸豚类动物。为了提供保护行动的信息，需要解决两个重要问题：存活率的阈值是多少，以及种群规模的阈值是多少？我们计算了不同幼豚和非幼豚存活率组合下长江江豚的瞬时种群增长率（ ）。我们还使用稳定种群模型测试了不同最小承载能力下 100 年和 500 年的灭绝概率。非幼豚存活率的阈值从未低于 0.869，但目前的实地数据估计远低于这一阈值。我们基于灭绝概率和承载能力的模型表明，种群规模要维持 100 年所需的阈值为 113 只动物，而要维持 500 年则需要 472 只动物。因此，我们建议建立一个易地保护区网络，以保证最小的 100 年承载能力。为了确保长期的种群生存能力，我们建议在两个湖泊及其周边保护区建立两个就地保护区，以满足最小的 500 年承载能力。此外，应该优先采取措施避免进一步的生境破碎化。
