90 DESCRIPTION OF IMPORTANT FISHERIES AND THEIR PRODUCTS 



freshly caught fish. The species has a fairly long pectoral fin, although 

 shorter than albacore. After albacore it gives the lightest color cooked 

 meat and so receives a higher price at the cannery than skipjack or 

 bluefin. Yellowfin is the largest volume species canned in the United 

 States. 



Skipjack (Katsuwonus pelamis). Skipjack is the smallest of the com- 

 mercial species and is distinguished by four or five broad, dark horizontal 

 stripes running along the lower part of the body. Individuals weigh up 

 to 20 pounds, the legal limit in California being 4 pounds. This species 

 is mainly supplied to United States canneries by the American fleet, 

 being fished off Central and South America. The recent conversion of 

 many bait boats to seiners resulted at first in a considerable drop in the 

 amount of skipjack landed, although Eastern Pacific stocks appear to 

 be large and relatively little exploited. Skipjack, being darker fleshed, 

 stronger flavored, and as a rule oiler than yellowfin, is less valuable than 

 other species. 



Bluefin. The name bluefin is applied to more than one species of the 

 genus Thunnus^^, which are distinguished in external appearance from 

 other tunas by a short pectoral fin which does not extend as far as the 

 insertion of the second dorsal fin. The Pacific bluefin is purse-seined and 

 can be as heavy as 250 pounds. A small amount is caught commercially 

 on the East Coast of the United States where it is also much sought as 

 a game fish. The flesh is generally dark, especially in the larger fish, which 

 is, therefore, of less value to the canner than albacore or yellowfin. 



Fishing Operation 



The considerable range of the United States tuna fishing operation has 

 had a profound effect on vessel design. Most of the large boats now in 

 use were designed for sustained live bait operation and so were equipped 

 to handle considerable amounts of fuel and live bait and to freeze and 

 hold large tonnages of tuna. Excellent descriptions of tuna boat refrigera- 

 tion equipment are given by Lassen and Rawlings^"^ and Hendrickson^^ 



The larger boats or clippers which comprise the greater part of the 

 American fleet are 120 to 130 feet long and carry 300 to 350 tons of tuna. 

 They are generally equipped with radar, D.F., radio telephone, fathom- 

 eters, etc. The crew consists of about 12 men who are usually paid on a 

 "share" principle. The engine room lies forward, and aft of this the 

 insulated wells which are used in turn for fuel, bait, and frozen fish 

 are set in pairs, one either side of the shaft alley. A typical l)ait boat 

 may have 10 wells and 3 refrigerated bait boxes set on the main deck at 

 the stern. The refrigerant used is ammonia which is fed from one of the 

 three compressors through a sea water condensor, a liquid manifold, and 



