18


 50
 50 m = .27

 E 40

 So 30

 S 20 m = .80

 10 \\ m = 4.94
 m=11.1 2.0 m= 1.4

 200 400 600 800 1000 1200 Effort


 Figure 3. Equilibrium yield relationships for various values
 of m



 The foregoing has presented a brief introduction to the biological

bases underlying the bioeconomic models currently utilized in fisheries

management. The Generalized Stock Production Model provides a framework

which is more general than Schaefer's formulation, but still enables the

expression of equilibrium catch as a function of fishing effort. As

noted above, the type of result is significant in that the generally

unobservable population variable is eliminated in favor of those

variables (catch and effort) which are observable.


 Basic Bioeconomic Models of the Fishery


 The previous section of this chapter presented the basic biological

relationships that create the framework within which the economic

aspects of fisheries production may be analyzed. The biological rela-

tionships it will be recalled, led to the concept of sustainable yield,

and suggested that the harvest of any given fishery be restricted to be