Migratory marine megafauna generally move vast distances between productive foraging grounds and environmentally stable breeding grounds, but characterizing how they use these habitats to maintain homeostasis and reproduce is difficult. We used isotope analysis of blue whale skin strata (n = 621) and potential prey (n = 300) to examine their migratory and foraging strategies in the eastern Pacific Ocean. Our results suggest that most whales in the northeast Pacific use a mixed income and capital breeding strategy, and use the California Current Ecosystem as their primary summer-fall foraging ground. A subset of individuals exhibited migratory plasticity and spend most of the year in the Gulf of California or Costa Rica Dome, two regions believed to be their primary winter-spring breeding grounds. Isotope data also revealed that whales in the southern Eastern Tropical Pacific generally do not forage in the northeast Pacific, which suggests a north-south population structure with a boundary near the equator.

迁徙性海洋动植物通常在生产性觅食场和环境稳定的繁殖场之间移动很远的距离，但是很难描述它们如何利用这些生境维持体内的稳态和繁殖。我们使用了蓝鲸皮层（621例）和潜在猎物（300例）的同位素分析。），以研究它们在东太平洋的迁徙和觅食策略。我们的结果表明，东北太平洋的大多数鲸鱼使用混合收入和资本繁殖策略，并将加利福尼亚州当前的生态系统用作夏季主要觅食场。一部分个体表现出可迁移性，并在一年中的大部分时间都在加利福尼亚湾或哥斯达黎加巨蛋中度过，这两个地区被认为是他们冬季冬春季的主要繁殖地。同位素数据还显示，东部热带太平洋南部的鲸鱼通常在东北太平洋不觅食，这表明南北种群结构在赤道附近具有边界。