The Importance of Foraging Pattern on Reproductive Success in the Northern Fur Seal, Callorhinus Ursinus

9500072科斯塔在过去的几十年里，许多鳍足动物和海鸟的数量都经历了显着下降。 人们提出了许多假设来解释这种下降，并进行了许多研究来寻找根本原因。 然而，幼鱼的存活率可能是影响鳍足类枯竭种群的生长和恢复的最关键因素之一。 母亲在断奶前给予后代的资源对于从营养依赖到独立的成功过渡以及随后的生存是重要的。 对于那些生活史受到高纬度地区养育后代的限制的物种和那些突然断奶的物种来说，情况可能尤其如此。 当生活史生殖力时间表限制个体每年生产一个后代时，高纬度地区枯竭种群的增长和恢复进一步受到限制。 因此，母亲对幼崽投资的数量和质量是断奶后存活的关键决定因素。 本研究将探讨北方海狗觅食行为与母体投资的关系。 这项研究将在阿拉斯加的普里比洛夫群岛进行，在那里，哺乳期的北方海狗被证明有三种不同的觅食模式（浅，深，混合）。 普里比洛夫群岛的位置靠近广阔的大陆架边缘，偶然地为在那里繁殖的动物提供了两个不同的觅食环境，一个在大陆上，一个在大陆外。 每个环境都有一个独特的猎物物种组合。 先前的研究表明，深潜觅食模式与大陆架觅食有关。 我们将量化的觅食成本和总投资的幼崽与不同的觅食策略观察到北方海狗。 这将通过比较母体在传递给幼犬的实际能量和物质以及母体的能量成本方面的投资来完成。 这些数据将用于确定一种觅食策略是否在能量上更有效或更有益，如果是这样，它是否允许母亲在她的年轻人身上进行更多的投资。

9500072 Costa Over the last several decades many populations of pinnipeds and seabirds have undergone significant declines. Many hypotheses to explain the declines have been made and numerous studies have been undertaken to search for the underlying causes. Juvenile survival, however, may be one of the most critical factors influencing the growth and recovery of depleted populations of pinnipeds. Maternal resources imparted to offspring prior to weaning are important for a successful transition from nutritional dependence to independence and subsequent survival. This may be particularly so of species whose life histories are constrained by rearing young at high-latitudes and species which wean their young abruptly. Growth and recovery of depleted populations at high-latitudes are further constrained when life- history fecundity schedules limit individuals to producing one offspring per year. Thus, the quantity and quality of maternal investment to the young are a critical determinant of post- weaning survival. This research will examine the relationship between foraging behavior and maternal investment in northern fur seals. The research will be conducted in the Pribilof Islands; Alaska, where lactating northern fur seals have been shown to have three distinct foraging patterns (shallow, deep, and mixed). The location of the Pribilof Islands, near the edge of an extensive continental shelf, fortuitously gives animals breeding there two distinct foraging environments, one on the continental and one off. Each environment has a distinct assemblage of prey species. Previous studies show the deep diving foraging pattern to be associated with foraging over the continental shelf. We will quantify the foraging costs and total investment in pups associated with the different foraging strategies observed in northern fur seals. This will be done by comparing the maternal investment in terms of both the actual energy and material delivered to the pup and the ene rgetic cost to the mother. These data will be used to determine if one foraging strategy is energetically more efficient or beneficial and if this is so, does it allow the mother to make a greater investment in her young.