In collective biological systems, social contagion processes play an important role in evaluating and processing information on the level of the collective. These group-level abilities typically arise from individual-level mechanisms and through local interactions. We are interested in the role of these mechanisms and their effect on the system’s response to environmental inputs. In this paper, we present a spatially embedded network model that is inspired by large fish shoals performing collective action in response to predation. We compare the observations of spatio-temporal dynamics in the model simulations with empirical observations, studying specifically the effect of spatial heterogeneities on system activity. The model demonstrates how already simple mechanisms suffice to represent key characteristics of the study system, and highlights the importance of taking into account the spatial embedding for understanding group-level processes in animal collectives.