been tried on a few occasions in Hawaiian waters 

 (Murphy and Niska, 1953). The method has 

 shown some promise ([U.S.] Bureau of 

 Commerical Fisheries, 1969a) and recently 

 another attempt (Hawaii. Fish and Game and 

 Bumble Bee Seafoods, 1970) has taken place 

 with partial success. In the western Pacific the 

 Japanese have been increasing tlieir experimental 

 and exploratory purse seine work, which is 

 summarized by Watakabe (1970). Like the 

 HawaiiaJi experiments, these efforts have not 

 been an unqualified success. American west 

 coast purse seiners have also made some excur- 

 sions into the western Pacific with mixed success 

 ([U.S.] Bureau of Commercial Fisheries, 

 1970b). Numerous reasons have been cited for 

 the difficulties encountered in applying this 

 method of fishing in the central and western 

 Pacific, chief among these being the greater 

 depth of the thermocline and the clearer waters 

 in the tropics. This method may yet become 

 increasingly important following development 

 work involving gear modifications and special- 

 ized techniques. 



Pole-and-line fishing with live bait is still the 

 preferred method in the central and western 

 Pacific. There are many references to live-bait 

 fishing in these areas from prewar years (Ikebe 

 and Matsumoto, 1937; Matsumoto, 1937; South 

 Seas Government-General, 1937a, b, c; Wata- 

 nabe, 1940; Ikebe, 1941) and numerous reports 

 from after the war including June (1951b), 

 Inoue (1966), Hida (1970b), and Uchida 

 (1970). 



Little has been published on new methods 

 (Alverson and Wilimovsky, 1964; Kristjonsson, 

 1968). Some work has been done on improved 

 purse seining (Green, Jurkovich, and Petrich, 

 1970) and purse seining in combination with live 

 bait (Hawaii. Fish and Game and Bumble Bee 

 Seafoods, 1970). 



Attracting and concentrating fish under 

 floating objects (Gooding and Magnuson, 1967; 

 Hunter and Mitchell, 1968) and electro-fishing 

 (Tester, 1959) are other methods that have been 

 tried or suggested. Recently the Japanese have 

 developed an automatic skipjack fishing device 

 which shows considerable promise (Suzuki 

 Tekkojo Kabushiki Kaisha, 1970) and the 

 Tahitian troll-pole method (Van Campen, 1953), 

 though not new, is a method that may well 

 prove applicable to other areas. 



Economics and Capital Investment 



Most of the information on cost and 

 investment economics is from industry, and the 

 data are proprietary and can only be obtained 

 by special arrangement with the appropriate 

 companies. Some information on the impor- 

 tance of skipjack fishery development for the 

 western Pacific is included in the Nathan Report 

 (Nathan Associates, 1966), in [U.S.] Bureau of 

 Commercial Fisheries (1969a), and in Pacific 

 Islands Development Commission (1971). Shang 

 (1969) discusses the economic aspects of the 

 Hawaiian skipjack fishery. Production figures are 

 generally available from a number of sources 

 including lATTC, the National Marine Fisheries 

 Service, the State of Hawaii, and the Japan 

 Fisheries Agency. 



FAG summarizes these statistics annually in 

 its Yearbook of Fishery Statistics (Food and 

 Agriculture Organization of the United Nations, 

 1970). These are generally several years late and 

 do not reflect the rapid changes that are 

 occurring. Because of the proprietary nature of 

 the data, the production figures often are pooled 

 for a large geographical area so it is impossible to 

 tell how many fish are landed from any one 

 location. 



SKIPJACK FISHERY MANAGEMENT 



With the rapid expansion of the skipjack 

 fishery, conservation and management of the 

 resource should be of concern to all interests. At 

 present there is no convention to manage and 

 protect the tunas of the central and western 

 Pacific. 



Management requires certain broad items of 

 information. The first is whether or not a fishery 

 exploits a single stock or several more or less 

 independent stocks or subpopulations. Generally 

 the skipjack population is believed to be 

 separated into a western Pacific stock that 

 ranges from the Philippine Sea to the home 

 islands of Japan and from the Ryukyus south to 

 New Guinea and into the Coral Sea, and a 

 central Pacific stock that probably extends from 

 the Carolines and the eastern side of the 

 Marianas all the way to the Americas. This 

 theory is supported by genetic evidence 

 summarized by Fujino (1967, 1970a, b, in press) 

 by morphometries (Kawasaki, 1955a, b, 1964), 



