Conversion to open water, prinnarily caused by natural flooding in western inland 

 basins, was responsible for 47 percent of the wetland conversion (fig. 33). Of 

 the human-induced wetland conversions, conversion to urban and developed 

 lands was responsible for 48 percent of the wetland loss, while agricultural 

 development was indicated in 37 percent of the converted wetland area. 



Wetland losses due to agriculture have declined since the mid-1 950's. During 

 the mid-1 950's to mid-1 970's, 87 percent of wetland losses were estimated to 

 be due to agriculture and for the mid-1 970's to mid-1 980's, 54 percent. 



There was a net loss of 262,400 acres of forested wetlands between 1982 and 

 1987. This amounted to 62 percent of the human-induced conversions. 



Percent of total area converted 



Flooding 



Built-up 



Agriculture 



43.6 



30.7 



24 



Forest 0.3 



D 



other 1.4 



A total of 970,000 acres was covered 



Figure 33-Causes of wetland loss, 1982-1987. 



Wildlife and Fish Demand-Supply Comparisons 



The number of people who hunt and fish is determined in part by the availability of 

 wildlife and fish habitats and populations. There are no reliable estimates of supply 

 variables for use in comparing fish and wildlife supplies and demands. Demand and 

 supply together determine consumption, which is measured by numbers of hunting 

 trips, animals harvested, or other means. Because it is so difficult to separate de- 

 mand and supply in analysis, it is difficult to interpret demand-supply comparisons. 

 For example, the demand for hunting might decrease because there are fewer 

 animals to hunt. 



To test these demand and supply interrelationships, we examined future consumption 

 under conditions of increased supply. This examination indicated that the biggest 

 potential gap between demand and supply is for cold water fishing, followed by 

 migratory bird hunting, big game hunting, and small game hunting. For these activi- 

 ties, increases in supply would lead to increases in consumption. 



60 



