Review of the trophic niches of baleen whales through isotopic evidence

Multi-regional assessments of the trophic niches of different baleen whale species can help elucidate patterns of interspecific and intraspecific variation and mechanisms of coexistence. Challenges in observing feeding dynamics of baleen whales make it difficult to characterize trophic dynamics on a large scale. Stable isotope analysis has been applied to studies of marine trophic ecology as a way to understand individual dietary sources of energy and nutrients as they move through a food web. Generation of Bayesian ellipses within a bi-plot space can allow us to map species trophic niches by means of their isotopic niche which may reveal underlying patterns in resource use within and between species. A detailed review of the variable differences of trophic niche width within and between different species and regions based on isotope analysis of baleen whales has not been previously published. We conducted a meta-analysis examining the isotopic niches from skin isotope data of blue, fin, and humpback whales collected in the Arctic, Atlantic, and Pacific oceans, in which we suggest patterns of niche overlap and partitioning both at the interspecific and intraspecific levels. Furthermore, we highlight variation in baleen whale plasticity to potential changes in environmental and anthropogenic stressors that may drive changes in habitat and resource use, specifically in regard to temporal and spatial variability in prey availability which can have negative consequences for baleen species in a rapidly changing environment.