Large numbers are imputed to tidal marshes for three types of oyster 

 aquaculture, including moderately intensive oyster aquaculture ($630 per acre 

 per year), intensive oyster aquaculture ($1,575 per acre per year), and intensive 

 raft aquaculture ($6,125 per acre per year). Again, these represent the average 

 value product of the marshes under the assumption that the marginal value product 

 of the other factors of production, including labor, are equal to zero. 

 Gosselink, Odum, and Pope make very little of the important distinction between 

 complementary and noncomplementary outputs provided by the marshes. Clearly, 

 the use of a marsh for aquaculture restricts provision of substitute goods and 

 services, such as tertiary waste treatment. But the authors do not add the value 

 of the aquaculture outputs to the value of the other (potential) outputs. The 

 panoply of outputs and values is completed by the imputation of a $2,500 per acre 

 figure for the alleged tertiary treatment output by tidal marshes and the 

 imputation of a $4,100 per acre value for the ecosystem life support function. 

 The ecosystem life support value is derived by using their estimate for the price 

 of energy. The fossil fuel needed to release 10 kilocalories (10,000 calories) 

 costs a dollar according Gosselink, Odum, and Pope. Thus the energy equivalent 

 of 10,000 kilocalories is a 1973 dollar. The life support functions are 

 essentially the same as in the paper by Gosselink and Pope; they represent the 

 conversion of solar energy into above ground plant biomass. However, the 

 discussion given in this article is a bit more complex because the authors 

 believe that some ecosystem life support functions, such as geochemical cycling, 

 are not captured by the narrow definition they use to determine the social 

 opportunity cost of wetlands loss. It is clear that the value of many of the 

 other human uses (recreation, tertiary waste treatment) can be added to the value 

 of the life support function, but an extended discussion of this tricky subject 

 would remove considerable ambiguity from their terse treatment. 



10. Hammack, J., and G.M. Brown, Jr. 1974. Waterfowls and wetlands: toward 

 bioeconomic analysis. Johns Hopkins University Press, Baltimore, MD. 

 95 pp. 



This is one of the cornerstones of bioeconomics. Hammack and Browntreat 

 prairie potholes as a factor input in the production of migratory waterfowl. 

 The methods, data, and conclusions are essentially the same as those reached in 

 their Review of Economics and Statistics article (see [5]). The book, however, 

 includes a more extensive background discussion of consumer surplus, the 

 contingent valuation method (CVM), mallard duck population dynamics, and other 

 management-oriented models of migratory waterfowl population dynamics. 



Hammack and Brown estimate linear and nonlinear production functions for 

 mallards with a regression model based on data for the number of Canadian prairie 

 potholes. They assume that the same production relation can be extended to all 

 North American waterfowl and all North American prairie potholes. The contingent 

 value method survey instrument that they used to establish the willingness-to- 

 pay for bagged waterfowl (above and beyond expenses) was only administered to 

 Pacific flyway hunters; the authors assume that the quantitative results can 

 be extended to the entire U.S. 



Aerial counts of the number of May and July prairie potholes were used to 

 establish annual time series data of the number of breeding ponds for the period 

 from 1955 to 1968. The July ponds estimate is, according to Hammack and Brown, 



17 



