Evolutionary dependencies of marine mammals on their preferred prey species: a potential paradigm shift to guide fisheries management and conservation initiatives

海洋哺乳动物和它们的猎物共同进化的一个营养后果似乎是，一些潜在的猎物物种不再具有足够丰富的能量来支持某些海洋哺乳动物物种的能量需求，而其他能量需求较低的海洋哺乳动物没有进化出高性能的肌肉结构，因此已经适应了依靠运动较慢和通常质量较低的猎物生存。因此，渔业和生态系统的变化改变了高能量和低能量猎物物种的相对丰度，可能会导致海洋哺乳动物数量的快速变化，这取决于海洋哺乳动物所走的进化道路，即使在潜在猎物物种的高生物量存在的情况下也是如此。这被称为“垃圾食品”假说。我建议使用生物能量学模型以及饮食信息和种群估计的区域时间序列来检验垃圾食品假说对海洋哺乳动物的普遍适用性。我将首先将详细的生物能量模型预测的所有海洋哺乳动物的食物需求与那些根据体重来衡量消耗量的广义方程得出的结果进行比较。我的预期是，这将导致至少两类海洋哺乳动物的新的广义消费方程，这些方程被它们进化为消费的猎物质量的差异分开。我还将对北太平洋海洋哺乳动物的种群动态进行详细的空间分析，以对比1975-1976年的海洋体制转变，当时阿拉斯加湾和加利福尼亚州的洋流系统中鱼类和海洋哺乳动物的显着增加和减少是相反的。在接下来的5年里，我将与4名研究生和5名本科生一起制定模型，并为深入研究的海洋哺乳动物物种，特别是北太平洋物种，建立必要的丰度、分布和食物数据库。我还将利用PICES成员国(日本、韩国、中国、俄罗斯、加拿大和美国)提供的数据，建立一个关于猎物数量、质量、组成和分布的补充数据库。我期望研究结果：1)建立海洋哺乳动物与其首选猎物物种之间的营养联系和依赖关系；2)产生估计海洋哺乳动物摄入量的新的通用方程式；3)检验垃圾食品假说作为海洋哺乳动物种群动态主要驱动力的适用性；4)有助于预测气候变化对海洋哺乳动物摄入量和分布的时空影响。这项研究支持的研究生将发展编程、数据分析以及渔业和海洋哺乳动物研究方面的技能；并将参加国际会议，以及在PICES年会上组织的研讨会和专题讨论会，以支持这一倡议。

A nutritional consequence of the co-evolution between marine mammals and their prey appears to be that some potential prey species are no longer energy-rich enough to support the energetic needs of some species of marine mammals, while other marine mammals with lower energy requirements did not evolve high performing musculature, and have therefore adapted to survive on slower moving and generally lower quality prey. As such, fishing and ecosystem shifts that alter the relative abundances of high-energy and low-energy prey species can cause rapid changes in marine mammal numbers depending on which evolutionary pathway the marine mammals followedeven when high biomasses of potential prey species are present. This has been termed the “junk food” hypothesis. I propose to test the general applicability of the junk food hypothesis to marine mammals using bioenergetic models and regional time series of dietary information and population estimates. I will begin by comparing the food requirements of all marine mammals predicted by detailed bioenergetic models with those derived from generalized equations that scale consumption as a function of body mass. My expectation is that this will result in new generalized consumption equations for at least two categories of marine mammals separated by differences in the quality of prey they evolved to consume. I will also undertake a detailed spatial analysis of the population dynamics of marine mammals in the North Pacific relative to the 1975-1976 Oceanic Regime Shift when significant increases and decreases of fish and marine mammals occurred opposite to one another in the Gulf of Alaska and the California Current System. For the next 5 years, I will work with 4 graduate students and 5 undergraduates to formulate the models and build the necessary databases of abundances, distributions and diets for the intensively studied species of marine mammals, particularly in the North Pacific Ocean. I will also establish a complementary database on prey quantity, quality, composition, and distribution using data provided by PICES member countries (Japan, Korea, China, Russia, Canada and the United States). I expect the results to 1) establish trophic linkages and dependencies between marine mammals and their preferred prey species, 2) yield new generalized equations for estimating consumption by marine mammals, 3) test the applicability of the junk-food hypothesis as the major driver of marine mammal population dynamics, and 4) aid in predicting the spatial and temporal effects of climate change on consumption and distribution of marine mammals. The graduate students supported by this study will develop skills in programming, data analysis, and fisheries and marine mammal research; and will take part in international conferences, and in workshops and symposiums organized at PICES annual meetings to support this initiative.**