Atlantic herring (Clupea harengus; hereafter herring) is a forage fish that transfers energy from lower to higher trophic levels and sustains high-volume fisheries in the North Atlantic. This study aims to improve our understanding of the ecology of Newfoundland herring and its vulnerability to climate change by identifying key prey items and describing adult herring feeding strategies. We compared plankton assemblages to stomach content and stable isotope analyses from herring collected in Trinity Bay, Newfoundland, in late summer and autumn 2017–2019. Six distinct zooplankton communities were identified across all years, with a shift in community structure in September 2018. This shift coincided with a change from fresher, warmer waters (12–17 °C) to more saline, cooler waters (10.5 °C). The most frequently consumed prey items were amphipods (Themisto spp.) and calanoid copepods (primarily Calanus and Temora spp.). Fish eggs, larvae, and juveniles, primarily identified as capelin, were observed in stomach contents in all years. Fish contributed most to diets in 2017, which corresponded with the peak year for larval densities in Trinity Bay, suggesting that piscivory may increase at higher larval densities. Herring were opportunistic feeders, although some individuals exhibited selective feeding on copepods, amphipods, euphausiids, and the early life stages of fishes. Stable isotope analyses supported the finding that herring piscivory is prevalent in eastern Newfoundland. Given its adaptive feeding strategy and wide range of consumed prey, we conclude that adult Newfoundland herring is resilient to bottom-up changes observed in the environment.

大西洋鲱鱼（Clupea harengus; 此后鲱鱼）是一种饲料鱼，可将能量从低营养级转移到高营养级，并维持北大西洋的高产量渔业。本研究旨在通过识别关键猎物和描述成年鲱鱼喂养策略，提高我们对纽芬兰鲱鱼生态及其对气候变化的脆弱性的理解。我们将浮游生物组合与 2017-2019 年夏末和秋季在纽芬兰三一湾采集的鲱鱼的胃内容物和稳定同位素分析进行​​了比较。多年来确定了六个不同的浮游动物群落，群落结构在 2018 年 9 月发生了转变。这种转变恰逢从更新鲜、更温暖的水域 (12-17°C) 到更咸、更冷的水域 (10.5°C) 的变化。最常食用的猎物是片脚类动物（Themistospp.) 和 calanoid 桡足类 (主要是Calanus和Temora种）。多年来，在胃内容物中都观察到了主要被鉴定为毛鳞鱼的鱼卵、幼虫和幼鱼。鱼在 2017 年对饮食的贡献最大，这与三一湾幼虫密度的峰值年份相对应，这表明在更高的幼虫密度下，食鱼可能会增加。鲱鱼是机会主义的饲养者，尽管有些个体表现出对桡足类、片足类、磷虾类和鱼类早期生命阶段的选择性取食。稳定同位素分析支持了鲱鱼在纽芬兰东部普遍存在的发现。鉴于其适应性喂养策略和广泛消耗的猎物，我们得出结论，成年纽芬兰鲱鱼对环境中观察到的自下而上的变化具有弹性。