yield-effort relationship is of this type. If the gear 

 can be adjusted to reject fish below a selected size, 

 a "eumetric" yield-effort function without a peak 

 can be realized. 



The assumption that recruitment is independ- 

 ent of population obviously cannot be of com- 

 pletely general validity over the population levels 

 relevant to any commercial fishery. For anadro- 

 mous fish such as salmon, the relationship is 

 critical. Nature is so profligate in her production 

 of fertilized eggs, however, that the case in which 

 the number of marine fish surviving to catchable 

 size is independent of the total standing stock over 

 relevant ranges is the rule rather than the excep- 

 tion. The other assumptions are less tenable. 

 Growth rates are almost certain to be density- 

 dependent, as are some types of natural mortality, 

 and the production possibilities impUcit in the 

 foregoing analysis are not necessarily reversible. As 

 the size of the desired stock is reduced through 

 commercial fishing, permanent shifts in predator- 

 prey relations and in relative numbers of compe- 

 ting food users may occur. Large and frequent 

 shifts in parameters are inevitable in the ecological 

 setting of the sea. 



If sense is to be made out of the concept of 

 optimum utilization of a fishery resource, at least 

 a rough delineation of physical production possi- 

 bilities is essential. Analysis of the potential of a 

 marine fishery population has progressed to the 

 point where yields can be estimated within satis- 

 factory limits for many stocks given estimates of 

 only a few parameters. The uncertainty about long 

 and short run effort-catch relations colors every 

 aspect of the high seas fisheries, and knowledge 

 does not come without its costs. But reasonably 

 accurate knowledge of yield-effort relations is 

 essential to development or management of any 

 fishery. 



These are crucial first steps toward efficient use 

 of living resources of the sea. But even when good 

 biological assessments of the size, range, and yield 

 from a given fish population are developed, man 

 seems determined to use it badly. Why is overfish- 

 ing so conmion in developed fisheries based on 

 valuable species? Why is the economic return in 

 such cases so low? Why does not the industry 

 provide, in its own interest, restraint on current 

 production in order to assure the largest possible 

 continued flow of output in the future? Answers 

 to these questions are vital to the long run welfare 



of the U.S. (and world) fisheries. The following 

 analysis of a hypothetical overfishing case provides 

 some of them. 



B. Economic Factors in Fishery Regulation 



Assume, first, that the long run relationship 

 between effort and yield, given the types of gear 

 employed, is firmly established by empirical re- 

 search. What level of effort and yield will actually 

 prevail in the absence of regulation? What level 

 should prevail? And if control is required to reach 

 an optimal position, what methods of regulation 

 should be used? These questions cannot be an- 

 swered on the basis of physical magnitudes alone. 

 Fisheries are carried on as commercial ventures in 

 the United States, and effort will expand or 

 contract as profit opportunities widen or narrow. 

 But the cost of fishing depends not only on 

 physical inputs of labor and capital but also on the 

 price which must be paid for their use; and the 

 money returns from fishing depend on both 

 physical yields and product prices. 



Total Receipts 



Fistiing Effort 



Figure 5. The effort/yield curve in relation 

 to total costs and total receipts. 



Assuming for the moment that fish prices, 

 wages, and costs of vessels and gear are fixed, the 

 effort-yield relation can be converted to one 

 showing total money receipts and total fishing 

 costs. 



As long as there are no restrictions on entry, 

 fishing effort will be pushed to the point where 

 total receipts and total costs, including a minimum 

 necessary profit to the vessel owner, are equal. At 

 any lower level, profits would attract new boats; at 

 any greater level, some would incur losses, and 

 eventually would be forced out of the fishery. 

 Obviously, any increase in prices or decrease in 

 costs would result in an increase in effort and 

 vice-versa. Full equilibrium in a fishery requires 

 not only that the physical catch be stable but also 



VII-63 



