88 DESCRIPTION OF IMPORTANT FISHERIES AND THEIR PRODUCTS 



which laid the basis for the development of a practical brine freezing 

 system. Although this system is far from perfect, its general adoption 

 by the American fleet in the following years caused a dramatic drop in the 

 level of rejects. 



The supply of tuna landed by the American fleet has for many years 

 now been augmented by frozen imported fish. This has consisted mainly 

 of ''round" albacore, "gilled and gutted" yellowfin, plus smaller amounts 

 of skipjack, and raw fillets. Recently a smaller amount of precooked and 

 cleaned frozen tuna has also been imported, mostly in the forms of ''loins" 

 but some shaped into can-size "discs." Total imports were relatively 

 small until after World War II when the increase was spectacular, sup- 

 plying almost the whole of the additional fish needed to meet the growing 

 requirements of the United States canners. Thus, while imported fish 

 accounted for only 1.4 per cent of the total United States supply in 1948, 

 by 1958 the proportion had grown to 35.9 per cent. Most of this tuna has 

 come from the Japanese fleet, much of the remainder from Peru, the 

 latter being mainly produced by United States operations. 



The intense competition of Japanese imports drove fish prices down 

 in 1955 below the level required for profitable operation. The resultant 

 attrition in the United States tuna fleet continued for some years, but 

 the position was reversed starting in 1959 by the conversion of a large 

 part of the bait boat fleet to a purse seining rig. The development of the 

 Puretic power block and nylon nets made deep-water seining a better 

 proposition than it had been formerly. The result was a dramatic reduc- 

 tion in the trip time, and the corresponding increase in annual yield and 

 profit enabled the domestic fleet to meet the competition offered by 

 imports and put it into a strong selling position. This vigorous tuna 

 seining activity has recently led to a depletion of the Pacific yellowfin 

 resource with a consequent decline in the catch per unit effort. 



The principal center of the tuna canning industry has remained in 

 Southern California (Terminal Island and San Diego), with some produc- 

 tion in the Pacific Northwest (chiefly at Astoria, Oregon). The continued 

 shift of fishing centers further south and to Atlantic waters has resulted 

 in the building of plants by some of the United States canners nearer 

 to these productive areas. Puerto Rico is the largest such center, strate- 

 gically placed to receive fish from both Atlantic and Pacific oceans and 

 to ship to United States markets on both coasts. Other American plants 

 are located in Samoa, Hawaii, Peru, and Ecuador. 



The Tunas 



Canned tuna is mostly prepared in the United States from four species. 

 These are: albacore, yellowfin, skipjack, and bluefin, although the com- 



