BIOLOGICAL BASIS 19 



movement westward of the "provisional" line initially set at 175° 

 West Longitude, even though, as })ointed otit below, the mainte- 

 nance of that line permits the Japanese fishermen to catch a dispro- 

 portionately great number of North American salmon. On the other 

 hand, ever since the inauguration of the treaty, the United States and 

 Canada have gradually conceded new areas and fisheries to Japanese 

 fishermen, first releasing from abstention in 1959 herring in Alaska, 

 and in 1963 halibiu in the eastern Bering Sea and the herring stocks 

 off the ^\ est coast of the Qtieen Charlotte Islands. 



BIOLOGICAL BASIS OF FISHERY MANAGEMENT 



One of the original objectives of the abstention principle ^vas to 

 permit the United States and Canadian fishermen to continue a care- 

 fully conceived program of management in the North Pacific, aimed 

 at producing the optimum sustained yield, without having that pro- 

 gram upset by the intrusion of other fishermen. Progress in the 

 biological and economic aspects of fishery regulation since 1953 has 

 continued to build the arguments favoring imposition of this prin- 

 ciple, especially in an area having the particular characteristics of 

 the northeastern Pacific. The basis of the principle, as ^\ell as its 

 appropriateness to the northeastern Pacific, has developed through a 

 number of different conferences and papers, and is still being 

 studied. The biological theory was summarized in the 1955 Rome 

 Conference, ^vhen the principle of maximum sustained yield was 

 recognized by all nations as essential for production of food from the 

 sea (United Nations, 1955). Biological theory was coordinated with 

 economic theory by the joint conference of economists and biolo- 

 gists held at the University of Washington in 1959 (Crutchfield, 

 1959a) and in Ottawa in 1961 (Hamlisch, 1962). Since some of this 

 theory has been applied in the formulation of recent treaties it is 

 necessary to review it briefly. 



Baranov (1918) was first to develop the theory that under certain 

 conditions of natural mortality, growth, and recruitment, there was 

 a certain intensity of fishing that wotild result in a maximum yield. 

 This is the theory that has led to the concept of "maximum sustained 

 yield." 



The mathematical model developed by Baranov ^vas based upon 



