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

海洋哺乳动物和猎物共同进化的营养后果似乎是，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组织，因此适应了以移动较慢且质量较低的猎物为生。因此，捕鱼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，这可能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遵循的进化途径，即使存在高生物量的潜在猎物物种。这被称为“垃圾食品”假说。我建议使用生物能量模型和饮食信息和人口估计的区域时间序列来测试垃圾食品假说对海洋哺乳动物的普遍适用性。首先，我将比较所有海洋哺乳动物的食物需求，这些食物需求是由详细的生物能量模型预测的，而这些模型是由消耗作为体重函数的广义方程推导出来的。我的期望是，这将为至少两类海洋哺乳动物建立新的广义的消耗方程，这两类哺乳动物是由它们进化到消耗的猎物质量的差异区分开来的。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，相对于1975-1976年海洋体制转变，当时阿拉斯加湾和加利福尼亚洋流系统中鱼类和海洋哺乳动物的显著增加和减少彼此相反。在接下来的5年里，我将与4名研究生和5名本科生合作，为深入研究的海洋哺乳动物物种制定模型，并建立必要的丰度、分布和饮食数据库，特别是在北太平洋。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。我希望这些研究结果能够：(1)建立海洋哺乳动物与其首选猎物之间的营养联系和依赖关系；(2)为估计海洋哺乳动物的食用量提供新的广义方程；(3)检验垃圾食品假说作为海洋哺乳动物种群动态的主要驱动因素的适用性；(4)有助于预测气候变化对海洋哺乳动物食用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、渔业和海洋哺乳动物研究的技能；并将参加国际会议，以及PICES年会组织的讲习班和专题讨论会，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.