The identification of interspecific links (trophic niche) is important to characterize resource use of a predator, and to know its trophic role (for example, mesopredator or top predator) in the food web. In this study, we examined: a) the trophic ecology of Scomberomorus sierra as a predator (niche breadth, trophic overlap, and trophic position) and b) its presence as a prey in the diets of the region´s top predators, to evaluate the critical link of S. sierra as a probable mesopredator in the food web of the southeastern Gulf of California (GC). Based on %PSIRI, the dominant diet of S. sierra were engraulids and cephalopods. The diet was similar between sexes and among size‐classes. However, the isotopic niche breadth values and δ¹⁵N variance (>1) reflect a broad niche for young adults likely related to a) changes in morphology (e.g., size of the mouth), b) development of the visual system, and c) changes in the energy requirements of the species reproductive stages. Seasonal changes in prey species’ availability and abundance resulted in isotopic variations, indicating that S. sierra is an opportunistic predator. A wide range in trophic position value (from 3.8 to 4.2) indicated that it also is an intermediary carnivore, with a high degree of trophic plasticity. Although S. sierra has not a dominant role in top predators’ diets, they share some prey species such as anchovies and other fish, depending on predator size. Therefore, S. sierra is a species with many prey‐predator relationships in the southeastern GC food webs that may be considered a critical trophic link. This information is crucial for an ecosystem‐based fisheries management in the Gulf of California.

中文翻译：

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加利福尼亚东南海湾太平洋山脉（Scomberomorus sierra）的营养小生境：评估其在食物网中作为掠食者和猎物（Mesopredator）的重要性

种间联系的识别（营养生态位）对于表征捕食者的资源利用以及了解其在食物网中的营养作用（例如中食者或顶级捕食者）很重要。在这项研究中，我们研究了：a）捕食者Scomberomorus sierra的营养生态（生态位宽度，营养重叠和营养位置），以及b）它作为该地区主要食肉动物饮食中的猎物而存在，以进行评估塞拉利昂链球菌可能是加利福尼亚东南部（GC）的食物网中可能的介壳虫的关键环节。基于％普西里，的主要饮食S.山脉是engraulids和头足类。男女之间和大小班级之间的饮食相似。但是，同位素生态位宽度值和δ¹⁵ N方差（> 1）反映了年轻成年人的广泛生态位，可能与a）形态变化（例如，嘴的大小），b）视觉系统的发育以及c）物种能量需求的变化有关生殖阶段。猎物物种的可利用性和丰度的季节性变化导致同位素变化，这表明塞拉链球菌是机会性捕食者。营养位置值的范围很广（从3.8到4.2）表明它也是一种中间食肉动物，具有很高的营养可塑性。尽管塞拉链球菌在顶级捕食者的饮食中并不占主导地位，但它们视捕食者的大小而共享一些猎物，例如an鱼和其他鱼类。因此，S。sierra是东南GC食物网中具有许多捕食者与捕食者关系的物种，可能被认为是至关重要的营养纽带。这些信息对于加利福尼亚湾基于生态系统的渔业管理至关重要。