The highly productive waters off Iceland are an important feeding ground for baleen whales. Five balaenopterid species coexist there during the summer feeding season: the blue whale, the fin whale, the sei whale, the humpback whale and the common minke whale. For capital breeders such as baleen whales, niche partitioning and reduced interspecific competition during their stay in the feeding grounds may be critical for the completion of their annual cycles and the long-term stability of populations. Coexistence often entails spatio-temporal or trophic segregation to avoid competitive exclusion. With the aim of studying how these species share habitat and trophic resources, we analyzed the δ¹³C, δ¹⁵N and δ³⁴S values in skin samples. Bayesian stable isotope mixing models to calculate compositional mixture of food sources showed that most species segregate by consuming different prey. Segregation was further enhanced by some degree of spatio-temporal exclusion. Overall, clear ecological niche partitioning was apparent between all species except between blue and fin whales. All the species consumed krill and, except for the common minke whale, this was the dominant prey. Among baleen whales, common minke whales and humpback whales were the major predators of sand eel, capelin and herring. In humpback whales, a strong reliance on krill may explain the apparently low rates of local entanglement in fishing nets as compared to other areas. Except for the blue whale, all species have shown evidence of adapting to shifts in prey availability and thus suggested capacity to cope with variability. However, in a scenario of increasing environmental variability associated to global warming, the overlap between ecological niches may have to decrease to allow long-term coexistence.

冰岛附近的高产水域是须鲸的重要觅食地。在夏季觅食季节，这里共存着五种长须鲸：蓝鲸、长须鲸、塞鲸、座头鲸和普通小须鲸。对于须鲸等资本繁育者而言，生态位划分和减少种间竞争在它们停留在觅食地期间可能对其年度周期的完成和种群的长期稳定至关重要。共存通常需要时空或营养隔离，以避免竞争排斥。为了研究这些物种如何共享栖息地和营养资源，我们分析了 δ ¹³ C、δ ¹⁵ N 和 δ ³⁴皮肤样本中的 S 值。用于计算成分 混合物的贝叶斯稳定同位素混合模型 食物来源表明，大多数物种通过食用不同的猎物来隔离。某种程度的时空排斥进一步加强了隔离。总体而言，除蓝鲸和长须鲸外，所有物种之间都存在明显的生态位分区。所有物种都吃磷虾，除了普通的小须鲸，这是主要的猎物。在须鲸中，常见的小须鲸和座头鲸是沙鳗、毛鳞鱼和鲱鱼的主要捕食者。在座头鲸中，对磷虾的强烈依赖可以解释与其他地区相比，当地渔网缠结率明显偏低的原因。除蓝鲸外，所有物种都表现出适应猎物供应变化的证据，因此表明有应对变化的能力。然而，