biologist who has become a population dy- 

 namics expert. This involves more than just 

 using the output of the population dynamics 

 expert; it entails understanding the intricacies 

 of this work so that it won't be misused. 



Here is where the first problems arise. Once 

 familiar with population dynamics models the 

 economist falls prey to the temptation to alter 

 components which may not be ideally suited to 

 his needs. What results is two versions of 

 population dynamics with one being the result 

 of both explicit and implicit imperfections in 

 the other. 



From this point several ramifications may 

 develop, depending on how far each conceptual 

 base may have been developed toward an actual 

 working management program. If this has oc- 

 curred original differences in population dy- 

 namics models will have been magnified. These 

 resultant differences generate a debate, and a 

 portion of this debate, as currently stated, is 

 contained in the following papers. To amplify 

 let me refer in greater detail to the twelve 

 points mentioned above. 



(1) The Need for New Yield Functions: The 

 biologist's yield function is the analogue of 

 the economist's production function. Produc- 

 tion economics focuses upon the allocation 

 of inputs to achieve production goals designat- 

 ed as optimum, this proper allocation being the 

 most efficient (least cost) combination of these 

 inputs. Partial derivatives, giving the incre- 

 mental contribution of each unit of a particu- 

 lar input, may be used to construct efficiency 

 indices roughly equivalent to the biologist's 

 measures of the fishing power of a vessel. 



These derivatives are obtained from general 

 form equations of a linear, Cobb-Douglas (con- 

 stant elasticity of substitution equal to one) 

 or C.E.S. (any constant elasticity of substitu- 

 tion) type. Contained within these general types 

 are certain assumptions concerning constant, 

 increasing, or decreasing returns (output) from 

 increasing increments of a particular input. 



Critical here is an appreciation of the fact 

 that these are fundamental calculations which 

 would be carried out whether or not any re- 

 lated biological work existed. When this work 

 does exist it serves as a reference point to the 

 economist as he proceeds systematically 

 through a series of steps dictated by the classi- 



cal scientific method which has evolved for 

 his profession. 



When, therefore, an economist specifies a 

 function implying diminishing returns to ad- 

 ditional inputs, we have the potential for debate 

 when the biologist has diminishing returns 

 due to population dynamics but constant re- 

 turns from a fixed biomass. These two differ- 

 ing approaches will lead to different evalua- 

 tions of the historical effort being exerted on 

 a fishery, to different estimations of the actual 

 yield curve, to different calculations of MSY 

 (maximum sustainable yield) and then to dif- 

 ferent management solutions. 



The issue becomes further complicated when 

 many species intermix and then must be con- 

 sidered simultaneously when designing and 

 operating a management program. The eco- 

 nomic portion of this analysis is actually more 

 readily solved in this case via a standard 

 analysis of the joint product case, whereas the 

 biological literature still carries a debate con- 

 cerning the proper use of Beverton-Holt dy- 

 namic pool models as opposed to the Schaefer 

 logistic approach. This issue is becoming more 

 critical as the trend in the technological capa- 

 bility of harvesting units is leading toward 

 some point in the future where the flexibility 

 and maneuverability of these units will make 

 all management considerations multispecies 

 to correctly reflect actual harvesting practices. 



(2 & 3) Economics and Biology in Measures 

 of Fishing Power: For management purposes 

 what is the appropriate emphasis of economics 

 and biology in bioeconomic models? One ex- 

 treme suggests that it is necessary to under- 

 stand the complete microdynamics of all stages 

 of the food chain, an ecological approach, and 

 all forces that act upon these stages, to proper- 

 ly specify the results of variation in fishing 

 effort and, therefore, to suggest the optimum 

 dimensions of that effort. This would confine 

 economists to a role of evaluating the economic 

 costs and benefits of the program suggested 

 by this detailed formulation. 



The opposite extreme finds the economist 

 placing the fisherman in an active role, where 

 he responds to various market incentives, 

 these responses subsequently becoming an in- 

 tegral step in determining variations in fi.shing 

 effort and resultant success. Some would 



