OBSERVATION OF SKIPJACK SCHOOLS IN HAWAIIAN WATERS IN 1953 



By 



William F. Royce and Tamio Otsu 

 Fishery Research Biologists 

 Pacific Oceanic Fishery Investigations 

 U. S. Fish and Wildlife Service 



For at least the past two decades the Hawaiian skipjack or "aku", Katsuwonus pelamis 

 (Linnaeus), has provided a major part of Hawaii's fish production. Except for the war years, 

 when there was almost no fishing, the skipjack fleet has consisted of about 20 to 25 boats, which 

 have landed about 10, 000, 000 pounds annually. This comprises from one-half to two-thirds of 

 the total fish production of the Territory (June 1950). Virtually all of the skipjack are taken by 

 chumming the schools of fish with live bait and catching the fish with pole and line from the stern 

 of the vessel. 



The nearly constant fleet and the absence of any clear up or down trend in 20 years 

 suggest that it has not been econonnical to enlarge the fishery. There appear to be two major 

 limiting factors, the first of which is a shortage of the essential live bait. The second is a 

 pronounced seasonal fluctuation, with high catches from about June to September and poor 

 catches during the balance of the year. Clearly, expansion of this fishery involves alleviation 

 of these two limiting factors, and the Pacific Oceanic Fishery Investigations (POFI) has com- 

 menced work on both problems. This report presents the results of the first year's study on 

 locating the fish, particularly in areas where and at times when they are not available to the 

 local fishery. In addition a comparison and evaluation of vessel and airplane scouting techniques 

 have been made. 



The study got under way in September 1952, using the research vessel CHARLES H. 

 GILBERT, which had been completed in May 1952. After two shakedown cruises, observations on 

 skipjack were begun. Cruises 3, 6, 8, and 12 were made near shore for testing artificial bait 

 or for bait surveys. Some scouting was done on these cruises, but it was incidental to other 

 objectives. On cruise 7, in February 1953, scouting was the principal objective, and a standard 

 scouting technique was developed which was used on cruises 11 and 13, in April and June 1953 

 respectively. Subsequently the HUGH M. SMITH was used for the standard scouting on cruises 22 

 to 24 from September to Decennber 1953. The second vital part of the scouting program was made 

 possible by the U. S. Navy, which furnished a PBY amphibian plane for six flights between 

 November 1952 and June 1953. 



The authors are greatly indebted to many members of the POFI staff who assisted with the 

 field observations, particularly to John W. Slipp, who was in charge of the skipjack investigation 

 until July 1953 and who standardized the methods of observing the bird flocks and fish schools. 

 Also deserving special nnention are Daniel T. Yamashita and Heeny S. H. Yuen, who with Slipp 

 and Otsu served as field party chiefs, and Albert K. Akana, Jr. , Robert E. K. D, Lee, and 

 Gordon M. Wilkinson, who captained the vessels on the cruises. We received excellent coopera- 

 tion from all U. S. Navy personnel concerned with the flights and from Rear Admiral W. K. 

 Phillips, who directed that the aircraft be made available. 



Valuable assistance was also received from Mr. Vernon E. Brock, Director of the 

 Division of Fish and Game of the Board of Agriculture and Forestry of the Territory of Hawaii, 

 who made available statistics on the skipjack fishery and who encouraged us in this study. 



