Fishing amplifies forage fish population collapses
Fishing amplifies forage fish population collapses
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DOI：
10.1073/pnas.1422020112
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发表时间：
2015-05-26
影响因子：
11.1
通讯作者：
Stawitz, Christine C.
中科院分区：
文献类型：
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作者：
Essington, Timothy E.;Moriarty, Pamela E.;Stawitz, Christine C.
饲料鱼支持世界上最大的渔业，但也在海洋食物网中发挥关键作用，将能量从浮游生物转移到上层营养级捕食者，如大型鱼类，海鸟和海洋哺乳动物。因此，除非采取保障措施，避免将饲料鱼类消耗到危险的低水平，否则捕捞会对海洋食物网产生深远的影响，而在低水平上，依赖鱼类的捕食者是最脆弱的。然而，由于这些种群对环境条件的敏感性，很难区分捕捞和自然过程对种群动态的影响。在这里，我们克服了这一困难，整理饲料鱼类种群的人口时间序列，占全球饲料鱼类捕捞量的近三分之二，以确定渔业的指纹，其人口动态。饲料鱼类种群崩溃具有一系列共同和独特的特征：崩溃前几年的高捕捞压力，自然种群生产力急剧下降，以及对减少捕捞压力的滞后反应。对自然生产力下降的滞后反应会急剧放大自然发生的人口波动的幅度。最后，我们表明，崩溃的规模和频率大于预期的自然生产力的特点，因此，可能归因于捕鱼。然而，崩溃的持续时间与基于自然生产力变化的预期没有什么不同。一个基于风险的管理计划，减少捕捞时，人口变得稀缺，将保护饲料鱼及其捕食者从崩溃，对长期平均渔获量几乎没有影响。
Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.