The research project MULTIWHALE addresses the urgent and complex challenge of how multiple stressors affect individual killer whales and populations, and how these responses can vary across time and between ecological groups of whales. The stressors we focus on are anthropogenic contaminants (including both legacy and emerging contaminants of concern), disturbance from tourism (boat traffic/whale-watching) and nutritional status (fluctuating prey resources). We investigate the response to these stressors in the context of intra-species variability in risk: some killer whales eat marine mammals in addition to fish and are thus exposed to higher levels of contaminants. We analyse how the difference in contaminant exposure affects the response to other stressors in these whales and, using modelling, how it affects population development and viability. Using long time trends from analysing archived teeth, we compare contaminant (mercury) and diet variation between whales in two periods of contrasting ecosystem states: 1960-1980 (collapse of the Norwegian Spring Spawning herring) vs. 1995-2015 (recovered ecosystem) to understand killer whale response and exposure to long term human impacts. The project team is composed of national and international leading experts on killer whale population and behaviour, gene expression, chemical analyses of legacy and emerging contaminants, dietary descriptors and health responses, population genetics and modelling - ensuring broad expertise and feasibility when assessing the effect of human interactions on whales status and health. We will work closely with our killer whale partners in Canada to exchange knowledge and protocols, and harmonise our methods to ensure future comparison across regions and populations. The MULTIWHALE results are relevant for understanding human impacts on killer whales, their harvestable prey resources (seal and fish) and for development of sustainable tourism.