FISHERY BULLETIN VOL. 72. NO. 1 



^= -0.0632 -0.005029(^j 

 (2.06) 



0.00051^ (27) 



(5.38) 



«2 = 0.816 



D-W = 0.619 



All of the independent variables are significant 

 at the 0.05 level. However, the Durbin-Watson 

 statistic indicates the strong possibility of posi- 

 tive autocorrelation. Nonetheless, we will use 

 these estimates as rough approximations to 

 obtain the price-dependent relationship as 

 shown in (26). Given 1969 values of exogenous 

 variables (A^ - 199.100,000; Y - $567,635 

 million; CPI = 109.8 with a base of 1967 = 

 100; Q + I = 158.8 million pounds), we have. 



P= 1.179 - (0.99853 X 10-^)Q.^. 



(28) 



Thus initial values for a (1.179) and ^ (0.99853 

 X IQ-^) have been obtained.-" 



-9 For purposes of simplification, the parameters of 

 the model are all assumed constant. Certainly, one could 

 argue that the parameters, so tacitly assumed to be 

 constants, are at best random variables. Therefore, a 

 stochastic treatment might be used with criteria like 

 maximal expected present value or minimal maximum 

 expected loss for evaluating the management alternatives 

 rather than simple deterministic computations. Possibly, 

 the parameters are random variables and conditional on 

 some of the suggested management alternatives. For 

 example, freezing effort might accelerate /■, leading to 

 shifts in season or age structure harvested, hence a change 

 in ulh. 



HOW THE MODEL WORKS: THE 

 IMPACT OF CRITICAL VARIABLES 



To illustrate the power of the model in ex- 

 plaining the impact of changes in critical 

 variables, we may derive initial quantitative 

 estimates of the ecological equilibrium and 

 economic steady-state functions. In this section 

 we will illustrate the power of the model in 

 explaining the impact of changes in critical 

 variables. The year 1969 is selected for initial 

 quantitative estimates of the ecological equi- 

 librium and economic steady-state functions. 

 Table 1 shows what happens to the value of 

 {X*, K*) as well as the equilibrium harvest 

 level. {Kx)*, when the following changes take 

 place: 



a) A 25% increase in opportunity costs of labor 

 caused by the development of greater regional 

 industrial activity; 



b) A 25% increase in the supply of other lobsters 

 traceable to the discovery of a new lobster 

 ground; 



c) A 5% increase in personal per capita income; 

 and 



d) A decrease in water temperature from 48° 

 to47°F. 



Notice that these changes are for illustrative pur- 

 poses; however they do come about on a routine 

 basis in the real world. Perhaps 25% changes 

 in selected variables do not come about in one 

 year so the reader can view the new equilibrium 



Table 1. — The impact of exogenous shocks to the inshore American lobster 

 fishery on the effort, catch, and biomass. 



20 



