equilibrium models of this type lose a great 

 deal of their utility as a basis for regulation. 

 The short run characteristics of the economic 

 adjustment process will be discussed later in 

 this paper but at this point it should be clear 

 that the short run economic and biological 

 adjustment processes are inexorably bound 

 up with each other. 



A second type of model, distinguished with- 

 in the biological literature, the dynamic pool, 

 presents an even thornier set of difficulties 

 for fisheries management.'- There are two prob- 

 lems inherent in dynamic pool models. The first 

 is that the maximum sustainable physical yield 

 is defined as a limit that can be reached only 

 by the expenditure of infinite fishing effort 

 (infinite cost). The second difficulty is more 

 analogous to those found in trying to maximize 

 the net economic yield from the resource. Vari- 

 ous degrees of overfishing and underfishing are 

 quantities of output which are deviations from 

 the eumetric yield curve or cui-ve of best yield, 

 i.e., catching the appropriate size of fish for 

 that level of fishing effort. Deviations from the' 

 eumetric curve are controlled by making 

 changes in the selectivity of the gear utilized. 

 The necessary conditions for making these 

 gear adjustments is a knowledge of the con- 

 dition of the stock and a reasonable degree of 

 flexibility in the regulatory pi'ocess. The ab- 

 sence of an operationally definable maximum 

 sustainable yield plus the necessity of adjust- 

 ing regulatoiy technique is a requii-ement on 

 management that is similar to the adjustments 

 in output level and inputs that would be re- 

 quired by changes in price and cost under 

 economic regulations. 



Forecasting with Biorogical Models 



In the commercial fisheries the forecasting 

 problem is a mix of the complexity of the life 

 cycle of the individual species and the avail- 

 ability of resources to carry on the necessary 

 biological research programs. For the bulk 



of the populations fished the effort devoted 

 to biological research is simply insufficient 

 to provide sophisticated forecasts. And while 

 at first glance the cure for this particular in- 

 adequacy would appear to be simple it is not. 

 In general it seems unlikely that sufficient 

 funds for meaningful broad-based biological 

 programs can be obtained except from the 

 income generated by the fisheries themselves.'-' 

 If this hypothesis is approximately valid then 

 it suggests that economic rationalization 

 (realization of the potential net yield) is a 

 necessary condition for achieving the level of 

 funding of biological research sufficient to 

 allow the development of dependable forecasts. 



The type of forecast made depends upon 

 the behavior characteristics of the species. 

 The Bristol Bay red salmon fishery has been 

 studied intensively by three agencies; the 

 National Marine Fisheries Service, the Alas- 

 kan Department of Fish and Game, and the 

 Fisheries Research Institute of the University 

 of Washington. 



Table 1 presents a summary of salmon runs 

 and a rough measure of the accuracy of the 

 forecasts for the recent decade. Despite the 

 investment in research and the heavy payoff 

 for accurate forecasts in the Bristol Bay 

 fishery it is clear that the existing forecasts 

 are not completely satisfactory.'^ Furthermore, 

 even if forecasting in this fishery was 100% 

 accurate the instability on the supply side 

 would (does) cause severe economic problems. 



Few other species present the forecasting 

 problems of the red salmon.'-^ In the simpler 

 cases it is possible to estimate the stocks, 

 and then assign under biological regulations 

 catch limits in some form. In subsequent 

 time periods the limits may be adjusted to 

 allow for errors in estimation of stock size. 



'2 From the viewpoint of the analysis of the biological 

 condition of the stock it appears to have certain ad- 

 vantages over the logistic model. 



'3 This follows from the common property status of 

 the resource which means that the rate of return to 

 the firm or the nation on investment, in research is 

 zero in long lOin equilibrium. 



'■* Crutchfield and Pontecorvo, (1969), especially 

 Chapter 7, develop the rationale for the high payoff 

 for accurate forecasts in Bristol Bay. 



'^ Schaefer (1970a), discusses the approach to the 

 maximum sustainable yield that may be utilized with 

 species such as the Peruvian anchoveta, halibut, etc. 

 Even within these, more stable populations there is 

 room for substantial disagi-eement about the appropri- 

 ate level of yield. For further examples see (Schaefer, 

 1967; 1970b and Segura, 1972). 



15 



