This paper develops the concept of a natural production function where ecological limits previously assumed constant are introduced as an input variable into the production function. This new class of production relations can consider variations in the state of nature such as beach erosion, declining wetland acreage and loss of forests as some prominent examples. Intuitively, the natural production function for ecological services (e.g., fish) can be specified as output per unit of time (a flow variable) as a function of labor, capital and nature where the latter variable entering the production functions as a factor of production. Such a factor of production varies due to exogenous events or manmade activities (e.g., pollution). The nature of the production surface for natural production functions was developed and contrasted with traditional engineering production function so widespread in economic theory. The natural production function was estimated for the commercial catch of shrimp, blue crabs and oysters with the state of nature being the wetland habitat in the Gulf of Mexico using cross-section data. For two (blue crabs and oysters) of the three species, increasing returns to scale were found when man's effort and the state of nature is enhanced proportionally. For all three species, the elasticity of substitution was about .9 indicating a high degree of substitution between man's effort and saltwater marsh in producing fish.