Fish and Wildlife Values 



Estuarine wetlands play an important role in the 

 life cycle of many fish species. Approximately two- 

 thirds of the major U.S. commercial fish species 

 spawn in estuaries and salt marshes (43). Fifty- 

 seven percent of the 10 most important recreational 

 marine fish species landed in 1979 also depended 

 on estuaries (28). Inland freshwater wetlands are 

 critical feeding, spawning, and nursery areas for 

 several freshwater fish species. For example, 

 marshes along Lake Michigan are used as spawning 

 grounds by northern pike, yellow perch, and carp. 

 Warmwater bass species use the southern bottom- 

 land hardwood forests as nursery and feeding 

 grounds (43). 



The species most closely associated with wetlands 

 are waterfowl. Waterfowl depend on wetlands in 

 the north for breeding areas, with the prairie 

 pothole region the most important breeding area in 

 the lower 48 States. It has been estimated that 20 

 percent of the annual continental production of 

 waterfowl occurs in wetlands in the lower 48 States 

 (38). Wetlands of the Chesapeake Bay, the Gulf 

 Coast, the Central Valley of California, and the 

 Mississippi River are major wintering areas for 

 waterfowl. Various wetlands are also used as 

 stopovers on migration routes (28). 



The 1985 census of duck populations indicates a 

 potentially bleak future for waterfowl. The mallard 

 population was at an all-time low of 5.5 million, a 

 47-percent decline from the first census figures in 

 1955. The sharpest decline occurred in the pintail 

 population, which was down 69 percent from 1955. 

 A variety of factors are blamed for these declines, 

 including hunting pressure, disease, and biological 

 stress. There is no debate, however, over the 

 critical role of habitat loss, especially in the prairie 

 pothole areas of Canada and the United States (33). 



At least 50 fur-bearing and other game species, in 

 addition to waterfowl species, depend on wetlands 

 for food, cover, or water. Most fur bearers, such as 

 muskrat, nutria, and mink, are wetland species. 

 Hundreds of nongame species also depend on 

 wetlands for feeding, breeding sites, and wintering 

 sites. Herons, egrets, cranes, storks, and ibises are 

 all wetland inhabitants. At least 35 endangered 

 species in the United States are wetland species, 

 mostly in California and the Southeast. 



Only about 10 million acres of wetlands in the 

 lower 48 States are protected through Federal 

 ownership, easement, or lease. Four million of 



those acres are in the National Wildlife Refuge 

 System (28). 



Ecological Values 



Wetlands perform a variety of ecological services. 

 For example, wetlands store flood waters and 

 retard flood peaks. The ability of a wetland to 

 reduce flooding depends on the size, topography, 

 and location of the wetland relative to downstream 

 areas, as well as the magnitude of the flooding. 

 Evidence indicates that wetlands are more effective 

 than terrestrial environments for storing flood 

 waters. Comparisons of watersheds with wetlands 

 and watersheds where wetlands have been drained 

 show that wetlands are important for delaying the 

 simultaneous arrival of flood peaks from tributary 

 streams to main stem channels (1). 



Wetlands improve water quality by trapping sus- 

 pended sediments and remove nutrients, pesticides, 

 and other toxic substances. Nutrient removal can 

 control eutrophication, the explosive growth and 

 decay cycle of algae, in adjacent waterbodies. 

 Because of these capabilities, freshwater wetlands 

 have been used to treat sewage effluent in some 

 urban areas. However, the ability to remove 

 sediments and adsorbed substances depends on the 

 density of vegetation in the wetland. Wetlands do 

 have a limited capacity to absorb such substances, 

 and can be overloaded (43). 



Wetlands have also been credited with both ground- 

 water recharge and discharge. Except in certain 

 regions (for example, cypress swamps and prairie 

 potholes), wetlands seem to have no inherent char- 

 acteristics for better recharge. However, data sug- 

 gest that wetlands are more important as water dis- 

 charge areas, and some can augment low flows (1). 



A variety of other services have been attributed to 

 wetlands. Wetland vegetation controls shoreline 

 erosion. This is particularly important along coasts, 

 where erosion can destroy public and private prop- 

 erty, clog navigable waters, and degrade fish and 

 wildlife habitat. Wetland plants are also efficient 

 converters of solar energy, and provide food for a 

 variety of species. Finally, it has been postulated 

 that wetlands moderate local temperatures, and 

 maintain regional precipitation and global at- 

 mospheric stability (1). 



Socioeconomic Values 



In addition to the values described above, wetlands 

 also yield other market and nonmarket benefits. 



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