Value of Marine Ecosystems on the Atlantic and Pacific Coasts

This chapter demonstrates that the ecosystems supporting the marine fisheries on Canada's east and west coasts have greatly changed under exploitation by industrial fisheries. These changes, reflected in the decline in the abundance of key species and the composition of the fisheries' landings, imply changes in the support provided by the ecosystems in which the fisheries are embedded. This further implies that ecosystem changes contribute sufficiently to the dynamics of fisheries to require their being considered explicitly in assessment and predictions, along with the within-species changes (e.g., of population structure or abundance) that have so far been the almost exclusive object of attention for fisheries scientists and managers. Some longer-term economic and ethical implications of the trends presented here are discussed, following a presentation of the ecosystems and of an index of fisheries impacts on them, from the beginning of the century to the present, for both the eastern and western coasts of Canada.