Answering the simple question, ‘who's counting’, reveals much about the spatial and cultural politics of ecosystem management. In this paper, I unite the concept of ‘ecocolonisation’ with the body of work on the politics of calculation. I argue that political technologies – including calculative techniques such as the enumeration of contamination levels – are a form of ecocolonisation that have considerable political effects on Indigenous communities. I explore the ways that historically connected Indigenous communities are divergently impacted by shellfish regulations and water pollution through an investigation of Boundary Bay, which straddles the Canada–US border on the Pacific coast. In closing, I suggest the on‐going need to decolonise our understanding of calculative techniques for ecosystem management, and offer a more nuanced interpretation of space that accounts for both traditional boundaries and connected ecosystems.