Some recent scholarship has focused on integrating local and/or traditional knowledge with conventional scientific information in fisheries management to improve the factual foundation of and strengthen support for management decisions. This article compares a sequence of historical and contemporary scientific texts and maps about the migrations and stock structure of cod in the Northern Gulf of St. Lawrence with texts and maps generated by the authors through the collection, aggregation and interpretation of commercial fish harvesters’ ecological knowledge. We find that the relationship between fisheries science and harvesters’ ecological knowledge is dynamic and has changed over time, and that both are ‘situated’ socially and ecologically. Overall, each paints an incomplete picture of cod movements and stock structure but the knowledge of harvesters provides a valuable complement to scientific information, particularly at the local scale, and has the potential to contribute to the identification of local cod stocks that are new to science and management. We end by considering how this case study informs the larger discussion about the challenges and potential benefits of the so-called integration project to bring together science and the ecological knowledge of fish harvesters.