Gauging allowable harm limits to cumulative, sub-lethal effects of human activities on wildlife: A case-study approach using two whale populations
Gauging allowable harm limits to cumulative, sub-lethal effects of human activities on wildlife: A case-study approach using two whale populations
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DOI：
10.1016/j.marpol.2016.04.023
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发表时间：
2016-08-01
期刊：
影响因子：
3.8
通讯作者：
Hammond, Philip S.
中科院分区：
文献类型：
--
作者：
Williams, Rob;Thomas, Len;Hammond, Philip S.
由于人类对海洋野生动物及其栖息地的亚致死压力增加，并以复杂的方式相互作用，迫切需要量化这些压力源对种群的累积影响的方法，以及关于允许伤害限度的政策决定。很少有研究量化个体压力源的人口后果，更少量化协同效应。排除所有不确定性来源可能导致预测范围从可忽略到灾难性。两个地方被确定为约束这个问题，通过充满活力的机制，减少猎物提供给个人。首先，美国海洋哺乳动物保护法的潜在生物去除（PBR）方程被用作占位符允许的伤害限制，以表示每年可以删除的动物数量，而不会使种群数量低于商定的管理目标。这将研究问题从“累积影响会有多大？“到“累积的影响要有多大才能超过商定的阈值？“其次，两个数据丰富的案例研究，即缅因州海湾座头鲸和东北太平洋居民虎鲸，被用作参数化最薄弱的环节，即猎物的可用性和人口统计之间的例子。在没有额外信息的情况下，该模型预测，人类活动只需要将虎鲸种群的猎物数量减少10%，就可以通过降低繁殖力和/或生存率来导致种群水平的捕获，相当于PBR。相比之下，在座头鲸人口，减少猎物的可用性类似50%，需要引起类似的，PBR大小的影响。本文描述了一种方法-结果只是说明性的。这两个案例研究在猎物专门化、生活史以及毫无疑问的承载能力方面存在差异。这种颠倒问题的方法重新聚焦于讨论猎物消耗的水平--通过与商业渔业的竞争、通过产生噪音的活动从觅食区转移、或用于探测猎物的信号的声学掩蔽--必须发生什么才能超过为渔业或其他更容易量化的人类活动中的致命捕获设定的允许伤害限度。(C)2016作者爱思唯尔有限公司出版
As sublethal human pressures on marine wildlife and their habitats increase and interact in complex ways, there is a pressing need for methods to quantify cumulative impacts of these stressors on populations, and policy decisions about allowable harm limits. Few studies quantify population consequences of individual stressors, and fewer quantify synergistic effects. Incorporating all sources of uncertainty can cause predictions to span the range from negligible to catastrophic. Two places were identified to bound this problem through energetic mechanisms that reduce prey available to individuals. First, the US Marine Mammal Protection Act's Potential Biological Removal (PBR) equation was used as a placeholder allowable harm limit to represent the number of animals that can be removed annually without depleting a population below agreed-upon management targets. That rephrased the research question from, "How big could cumulative impacts be?" to "How big would cumulative impacts have to be to exceed an agreed-upon threshold?" Secondly, two data-rich case studies, namely Gulf of Maine humpback and northeast Pacific resident killer whales, were used as examples to parameterize the weakest link, namely between prey availability and demography. Given no additional information, the model predicted that human activities need only reduce prey available to the killer whale population by similar to 10% to cause a population-level take, through reduced fecundity and/or survival, equivalent to PBR. By contrast, in the humpback population, reduction in prey availability of similar to 50% was needed to cause a similar, PBR-sized effect. The paper describes an approach - results are merely illustrative. The two case studies differ in prey specialization, life history, and, no doubt, proximity to carrying capacity. This method of inverting the problem refocuses discussions around what the level of prey depletion - via competition with commercial fisheries, displacement from feeding areas through noise-generating activities, or acoustic masking of signals used to detect prey - would have to occur to exceed allowable harm limits set for lethal takes in fisheries or other, more easily quantifiable, human activities. (C) 2016 The Authors. Published by Elsevier Ltd.