The paper provides an overview of eastern Baltic cod (Gadus morhua) fisheries from the end of the 1880s until 1938, in order to improve the knowledge of long-term stock dynamics. The data compiled and included in the study comprise catches and economic values of exploited fish species, time series of indicators of fishing effort and qualitative information on developments in fishing technology. This information has been assembled for different countries and locations in the Baltic Sea. We first summarize the multi-decadal development of national cod fisheries and their relative importance during the first decades of the 20th century. We then assess whether these data can be used to estimate the relative roles of fishing and ecosystem changes on variations in catches. We conclude that the assembled data reveal biologically meaningful variations in the state of the cod stock and that some of the variations in the catches of different countries (e.g. decline in the late 1920s; increase in the late 1930s) were caused by factors other than fishery developments. These factors probably include ecosystem-induced variations in cod population dynamics and need further investigation. (c) 2007 Elsevier B.V. All rights reserved.