Chicago Zoological Society, Brookfield, IL 60513, USA.
Oceans Initiative, Seattle, WA 98102, USA.
Sci Rep. 2017 Oct 26;7(1):14119. doi: 10.1038/s41598-017-14471-0.
Understanding cumulative effects of multiple threats is key to guiding effective management to conserve endangered species. The critically endangered, Southern Resident killer whale population of the northeastern Pacific Ocean provides a data-rich case to explore anthropogenic threats on population viability. Primary threats include: limitation of preferred prey, Chinook salmon; anthropogenic noise and disturbance, which reduce foraging efficiency; and high levels of stored contaminants, including PCBs. We constructed a population viability analysis to explore possible demographic trajectories and the relative importance of anthropogenic stressors. The population is fragile, with no growth projected under current conditions, and decline expected if new or increased threats are imposed. Improvements in fecundity and calf survival are needed to reach a conservation objective of 2.3% annual population growth. Prey limitation is the most important factor affecting population growth. However, to meet recovery targets through prey management alone, Chinook abundance would have to be sustained near the highest levels since the 1970s. The most optimistic mitigation of noise and contaminants would make the difference between a declining and increasing population, but would be insufficient to reach recovery targets. Reducing acoustic disturbance by 50% combined with increasing Chinook by 15% would allow the population to reach 2.3% growth.
了解多种威胁的累积效应是指导有效管理以保护濒危物种的关键。东北太平洋极度濒危的南方居留地虎鲸种群为探索人口生存能力的人为威胁提供了一个数据丰富的案例。主要威胁包括：限制首选猎物奇努克鲑鱼；人为噪音和干扰，降低觅食效率；以及高水平的储存污染物，包括 PCB。我们构建了一个种群生存力分析模型，以探索可能的人口轨迹和人为压力源的相对重要性。该种群很脆弱，在当前条件下预计不会增长，如果施加新的或增加的威胁，则预计会下降。需要提高生育力和幼崽存活率，以达到 2.3%的年度人口增长率的保护目标。猎物限制是影响人口增长的最重要因素。然而，仅通过猎物管理来达到恢复目标，奇努克鲑鱼的数量就必须保持在自 20 世纪 70 年代以来的最高水平附近。对噪音和污染物的最乐观的缓解将使人口数量在下降和增加之间产生差异，但不足以达到恢复目标。将声干扰降低 50%，同时将奇努克鲑鱼增加 15%，将使该种群达到 2.3%的增长率。
