PNAS：厄尔尼诺现象对鲑鱼生存的影响

摘要 : 美国加州大学戴维斯分校科研人员报告说，太平洋鲑鱼资源的稳定性在近几十年来下降。

美国加州大学戴维斯分校科研人员报告说，太平洋鲑鱼资源的稳定性在近几十年来下降。在历史上，东北太平洋鲑鱼种群生存的变化一直是通过太平洋十年振荡(PDO)加以解释的，这是一种由厄尔尼诺相关东太平洋变暖驱动的重复出现的海洋条件变化模式。近来，与太平洋十年振荡(PDO)相比，另一种厄尔尼诺相关模式——北太平洋环流振荡(NPGO)对海洋条件施加的影响增加，但是北太平洋环流振荡(NPGO)对鲑鱼生存率的影响尚未得到充分理解。D. Patrick Kilduff 及其同事追踪了1980年到2006年之间北美西部孵化场的Chinook 鲑鱼和Coho鲑鱼的生存。与太平洋十年振荡(PDO)相比，这两个物种的生存率的变化与北太平洋环流振荡(NPGO)更加密切相关。此外，在这两个物种的生存率之间的相似性从20世纪90年代初到现在增加。生物多样性倾向于稳定生态系统服务，其方式与多样化的持股让投资回报稳定相同。因此，不同鲑鱼物种的生存率相似性的增加，提示了鲑鱼生存的总体稳定性下降。这组作者说，鲑鱼管理策略应当考虑到由于北太平洋环流振荡(NPGO)造成的鲑鱼生存的变化性。

原文链接：

Changing central Pacific El Niños reduce stABIlity of North American salmon survival rates

原文摘要：

Pacific salmon are a dominant component of the northeast Pacific ecosystem. Their status is of concern because salmon abundance is highly variable—including protected stocks, a recently closed fishery, and actively managed fisheries that provide substantial ecosystem services. Variable ocean conditions, such as the Pacific Decadal Oscillation (PDO), have influenced these fisheries, while diminished diversity of freshwater habitats have increased variability via the portfolio effect. We address the question of how recent changes in ocean conditions will affect populations of two salmon species. Since the 1980s, El Niño Southern Oscillation (ENSO) events have been more frequently associated with central tropical Pacific warming (CPW) rather than the canonical eastern Pacific warming ENSO (EPW). CPW is linked to the North Pacific Gyre Oscillation (NPGO), whereas EPW is linked to the PDO, different indicators of northeast Pacific Ocean ecosystem productivity. Here we show that both coho and Chinook salmon survival rates along western North America indicate that the NPGO, rather than the PDO, explains salmon survival since the 1980s. The observed increase in NPGO variance in recent decades was accompanied by an increase in coherence of local survival rates of these two species, increasing salmon variability via the portfolio effect. Such increases in coherence among salmon stocks are usually attributed to controllable freshwater influences such as hatcheries and habitat degradation, but the unknown mechanism underlying the ocean climate effect identified here is not directly subject to management actions.

doi: 10.1073/PNAS.1503190112

作者：D. Patrick Kilduff

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