To understand species-level population dynamics, we need to understand the reproductive decisions made by individuals. In Atlantic cod, a large empirical literature has identified a number of individual-level traits that can influence mating decisions. However, mating decisions do not occur in isolation, but in relation to the network of other individuals within the population. Currently, it is unclear how these mating decisions about individual-level traits lead to different sexual network structures at a larger scale, and in turn how this influences the reproductive output of the population. It is particularly important to understand these relationships in the context of human-related impacts, such as climate change and fisheries management strategies. To bridge these scales, this working group will use techniques from network science to analyze a uniquely detailed dataset from a semi-natural experiment on Atlantic cod, a commercially and economically important model species. We will produce a detailed, empirically parameterised sexual network, that will allow us to answer key biological questions, and to simulate the future impacts of climate change.