Enhancement of populations of anadromous fishes

Dam removal has become increasingly popular, particularly as regards enhancement of populations of anadromous fishes--salmon and steelhead in the western U.S. and shad, herring and other species in the eastern U.S. Figure 13 illustrates the dams that have been removed in the lower 48 states (Figure 14 expands the eastern U.S.) from 1936 to 2013 on the basis of data tabulated by American Rivers. These dams have been removed largely to improve the ecological conditions of river systems and to allow migratory fish to pass unimpeded for spawning in the upper reaches of rivers. Dam removal is commonly cited as a way of increasing stocks of imperiled fishes (Chesapeake Quarterly: Those Dammed Old Rivers), allowing them to spawn in rivers that have been inaccessible to fish migration for as much as a century. Others argue that dam removal from coastal rivers is only part of the solution for fisheries improvements. Although numbers of anadromous fish may increase, the size of individual fish may not as long as fishing pressure remains the same (Oregon State University: Department of Fisheries and Wildlife). This has been argued in the case of Elwha Dam removal in the Olympic National Park watershed (Crosscut: Elwha dams: Will bringing down NW dams really help salmon?). In some cases the benefits will accrue to native Americans who formerly depended on fishing for their nutrition and livelihood.

×

Figure 13. Map of the lower 48 states showing locations of dams removed from 1936 to 2013. On the American Rivers website the locations are clickable to show information on each dam removed.
Source: American Rivers. Used with permission. All rights reserved.

×

Figure 14. Blow up of eastern U.S. portion of the dam removal map.
Source: American Rivers. Used with permission. All rights reserved.