SPECIES AND BROOD. N D J F M A M | J J A S N D J f " A 



Figure 1. - Brood year classification of species propagated from the beginning: of October 



1968 through April 1970. 



one of these variables and water temperature, 

 the food variable was retained in further 

 analyses. 



Marginal Factor Productivities 

 and Returns to Size 



Since the underlying functional relation- 

 ships were unknown, output response func- 

 tions were estimated in both linear and log- 

 linear (Cobb-Douglas) forms. Within each func- 

 tional form, estimates were obtained relating 

 to two different assumptions about the inter- 

 cept term.** The output response functions and 

 marginal physical productivities are shown 

 in Table 2. 



Several items are worthy of note. First, the 

 /?2 values were uniformly high, regardless of 

 functional form. Second, the marginal pro- 

 ductivity estimates appeared reasonable and 

 were fairly constant over the various functional 

 forms. The marginal productivity of one pound 

 of food was about 0.58 pounds of salmon, a 



"* While output would logically be zero if all input 

 levels were zero, an estimate of the intercept may be 

 helpful in assessing the "constant returns" argument 

 for the linear function. 



Table 2. — Output response functions and marginal 

 physical productivities for the 15 Oregon Fish Com- 

 mission salmon hatcheries. 



(.01) (.05) (.05) 

 .563 -16.735 29.715 



11. (a) Log-Linear 



11. (b) Log-linear 



23.74 

 (.01) 



1.106 



(.01) 

 .620 



- .334 



(-20) 



-11.281 



.526 



(.05) 



31.618 



1.047 - .450 .332 



(.01) (.10) (.20) 



.588 -15.217 19.958 



' Variables 

 Y = 



.960 



.999 



pounds of output of salmon (released either as 



fingerlings or swim-up fry) 



pounds of food fed (Oregon Moist Pellet). 



average cumulative temperature units (CTU's) of 



water from May through October (warm season). 



average CTU's of water from November through 



April (cold season). 

 - Regression coefficients. 

 -^ Significance level. 

 "" Marginal physical productivities. 





^r 



137 



