Historical Impacts on River Fauna, Shifting Baselines, and Challenges for Restoration

The decimation of aquatic wildlife through overexploitation is usually perceived as a marine phenomenon, yet it has also been common in freshwater ecosystems. Fish and other aquatic animals were superabundant when Europeans first arrived in North America and Australia, and were intensively exploited soon after. Contemporaneously, the construction of barriers in rivers increasingly prevented many species from migrating. Populations usually crashed as a result. Natural resource managers have not fully considered the ecological impacts of the devastation of these species to the environmental degradation that we see today, yet these impacts are likely to be pervasive. Nor have resource managers embedded the role of these species in river restoration. We argue that the functions of these depleted stocks need to be considered and perhaps reestablished if river restoration efforts are to be successful. The establishment of freshwater protected areas may be the most effective way to do this.