Average cost curve 



Average yield curve 



Fishing effort 



Figure 2. — Maximum, average, and minimum catch curves for a single fish stock. 



Average yield curve 



Fishing effort 



Figure 3. — Maximum, average, and minimum catch curves for a multiple stock fisheiy. 



between two extremes determined by the 

 abundance in the stock considered but which also 

 depend upon the abundance in the neighboring 

 stocks. It should be noted that the shape of the 

 resulting curve and the location of the point of 

 equilibrium would have to be determined for 



each particular case. Each case would not only 

 be the result of the structure of the given fish 

 stock and of the exploitation borne by this 

 stock, it would also be the result of the structure 

 of the other stocks which would be more or less 

 attractive, i.e., profitable. The findings of the 



98 



