Zabel Richard W, Scheuerell Mark D, McClure Michelle M, Williams John G
National Marine Fisheries Service, Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA.
Conserv Biol. 2006 Feb;20(1):190-200. doi: 10.1111/j.1523-1739.2005.00300.x.
The viability of populations is influenced by driving forces such as density dependence and climate variability, but most population viability analyses (PVAs) ignore these factors because of data limitations. Additionally, simplified PVAs produce limited measures of population viability such as annual population growth rate (lamda) or extinction risk. Here we developed a "mechanistic" PVA of threatened Chinook salmon (Oncorhynchus tshawytscha) in which, based on 40 years of detailed data, we related freshwater recruitment of juveniles to density of spawners, and third-year survival in the ocean to monthly indices of broad-scale ocean and climate conditions. Including climate variability in the model produced important effects: estimated population viability was very sensitive to assumptions of future climate conditions and the autocorrelation contained in the climate signal increased mean population abundance while increasing probability of quasi extinction. Because of the presence of density dependence in the model, however we could not distinguish among alternative climate scenarios through mean lamda values, emphasizing the importance of considering multiple measures to elucidate population viability. Our sensitivity analyses demonstrated that the importance of particular parameters varied across models and depended on which viability measure was the response variable. The density-dependent parameter associated with freshwater recruitment was consistently the most important, regardless of viability measure, suggesting that increasing juvenile carrying capacity is important for recovery.
种群的生存能力受到诸如密度依赖和气候变异性等驱动因素的影响，但由于数据限制，大多数种群生存能力分析（PVA）都忽略了这些因素。此外，简化的PVA产生的种群生存能力衡量指标有限，如年种群增长率（λ）或灭绝风险。在此，我们开发了一种受威胁的奇努克鲑鱼（Oncorhynchus tshawytscha）的“机制性”PVA，基于40年的详细数据，我们将幼鱼的淡水补充量与产卵者密度相关联，并将海洋中第三年的存活率与大规模海洋和气候条件的月度指数相关联。在模型中纳入气候变异性产生了重要影响：估计的种群生存能力对未来气候条件的假设非常敏感，并且气候信号中包含的自相关性增加了平均种群丰度，同时增加了准灭绝的概率。然而，由于模型中存在密度依赖，我们无法通过平均λ值区分不同的气候情景，这强调了考虑多种衡量指标以阐明种群生存能力的重要性。我们的敏感性分析表明，特定参数的重要性因模型而异，并且取决于哪个生存能力衡量指标是响应变量。无论生存能力衡量指标如何，与淡水补充相关的密度依赖参数始终是最重要的，这表明提高幼鱼承载能力对种群恢复很重要。
