The mystery of how and why large whales know when and where to migrate has perplexed humankind for thousands of years – first in their attempts to hunt and kill them and now to save them from extinction and exploitation. Right and bowhead whales are among the largest animals on Earth, yet they feed on some of the smallest marine organisms, zooplankton. This connection through the food web dramatically highlights associations of species linked closely to climate-induced changes in the oceans, such as recent rapid warming of the Gulf of Maine. Large filter-feeding whales, as ecological sentinels, are therefore a highly visible sign of underlying ocean health and conditions. This lecture will explore pressing questions surrounding large whale conservation and describe cutting-edge quantitative methods being used to understand whale distributions in the Anthropocene.