AGNELLO and DONNELLEY: INTERACTION OF FORCES 



demand, the income effect is positive if oysters are 

 a normal good, and the related good (poultry) is 

 most likely a substitute for oysters. 



Since the fixed supply assumption removes the 

 simultaneity from the model, both the supply and 

 demand functions can be interpreted as reduced 

 forms, and estimated directly by ordinary least 

 squares regression techniques without regard to 

 problems of identification. The demand function is 

 solved for its only endogenous variable, price, and 

 estimated in this form. The reduced form equa- 

 tions estimated later in the paper are written 

 below. 



SupplyQ = S(MSX,P,_i) 



+ + - 

 Demand P = D2{I,P,,Q) 



where Q is predetermined. 



In addition to conclusions concerning parameter 

 signs and elasticity values, implications of 

 property right structures are revealed in the 

 model. It is hypothesized that in states relying 

 more heavily on common property rather than 

 private leasing of subaqueous beds, the depletion 

 effect should be greater. The lagged price variable 

 in supply should thus have a negative coefficient 

 value for common property right areas. 



DATA 



Regression analyses are performed on the above 

 model for the Middle Atlantic and Delaware Bay 

 regions. The Middle Atlantic region is defined to 

 include the five contiguous coastal states of Vir- 

 ginia, Maryland, Delaware, New Jersey, and New 

 York. This region includes the productive 

 subaqueous resources of Chesapeake Bay, 

 Delaware Bay, and part of Long Island Sound. The 

 Delaware Bay area includes the states of 

 Delaware and New Jersey only. We anticipate 

 depletion to be a more important factor in the 

 regional analyses which are dominated by the high 

 production levels of Maryland and Virginia. These 

 Chesapeake Bay states (especially Maryland) rely 

 to a greater extent on common property than do 

 the Delaware Bay states. The latter states allow 

 much more extensive private leasing, and hence 

 supply a greater proportion of their oysters from 

 private leaseholds which may be expected a priori 

 to be less subject to overfishing with the ensuing 

 depletion. 



Time series annual data on quantities landed (in 

 pounds) and implicit prices are obtained from 

 Fishery Statistics of the United States (1940-1970) 

 compiled by the Bureau of Commercial Fisheries 

 of the U.S. Department of Commerce and the U.S. 

 Department of the Interior. Data on the price of a 

 related commodity in demand (i.e., the price of 

 poultry) and personal income are obtained from 

 the Bureau of Labor Statistics (U.S. Department 

 of Labor) and the Survey of Current Business 

 (U.S. Department of Commerce), respectively. The 

 biological variable representing the MSX disease 

 included in the oyster supply function of the model 

 was obtained from site sampling of oysters in the 

 Delaware River." The regions of consumption and 

 production are not identical in that the consump- 

 tion area includes a somewhat larger area. Precise 

 definitions of the variables used are given below. 

 Q Quantity per capita of oyster landings 

 (measured as pounds per person) for 

 Delaware Bay includes Delaware and New 

 Jersey, and regional quantities include the 

 five states of Delaware, New Jersey, 

 Maryland, Virginia, and New York. Popula- 

 tion refers to the seven-state region includ- 

 ing New York, Pennsylvania, New Jersey, 

 Delaware, Maryland, District of Columbia, 

 and Virginia. 

 P Price of oysters measured in dollars per 



pound (meat weight). 

 Pf _i Price of oysters lagged 1 yr. 

 MSX Biological variable referring to a pro- 

 tozoan oyster parasite commonly called the 

 MSX disease. 

 / Personal income per capita (deflated by the 

 Consumer Price Index for all items) for the 

 seven-state region including New York, 

 Pennsylvania, New Jersey, Delaware, 

 Maryland, District of Columbia, and Vir- 

 ginia. 

 P^f^ National average price per pound for 

 chickens (live weight). 



EMPIRICAL RESULTS 



We now turn to a brief discussion of the detailed 

 findings, and conclude with some general remarks 

 and policy implications. Tables 1 and 2 present the 



"The average annual prevalence of the MSX disease in a test 

 sample of oysters in the Delaware River was obtained from H. 

 Haslcin of Rutgers University. These percentages were zero 

 before 1957 and exceeded 50% in some later years. 



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