In the decades since World War II, large-scale ecological changes have affected fishing communities across the northern Atlantic. Substantial declines hit their historically important resources, most notably the Atlantic cod. Such declines were often accompanied by increases in other, previously less exploited, species. Interactions between fishing pressure and environmental variation have driven ecological change. Ecological changes in turn reshaped the fisheries, contributing to altered demographic profiles of fisheries-dependent communities. Many places lost population, especially through out-migration of young adults. Broad social forces also contributed to these trends, but the timing and geographical details of population changes often correspond to specific fisheries/ecological events.