Spawning locations of marine fish set the initial conditions for processes that influence survival, abundance, distribution, and the structure of the adult populations. The prevailing paradigm for the completion of the life cycle indicates that maine fish spawn in few and geographically constrained locations that favor the survival of the offspring. By analyzing a unique 16-year data of Atlantic cod (Gadus morhua) eggs catches over the entire Norwegian coastline, we demonstrate that cod spawning is ubiquitous, and that the oceanographic conditions that are associated with cod egg catches, such as water temperature, salinity, and current speeds, vary by region. Collectively our results underscore a high level of local adaptation in Atlantic cod, provide the foundation for a new framework to characterize marine fish life cycle, and offer a critical baseline for managing and conserving coastal marine habitats.