DISTRIBUTION AND ABUNDANCE OF SKIPJACK IN THE 

 HAWAII FISHERY, 1952-53 



By Herbert H. Shippen, Fishery Research Biologist, 

 Blreau of Commercial Fisheries 



A study of the environmental factors that may 

 influence the availability of the skipjack {Katsu- 

 wonus peJamis) to the Hawaii fishery was begun 

 by the staff of the U.S. Fish and Wildlife Service 

 Biological Laboratorj' (Honolulu, Hawaii). Be- 

 cause the index of availability is to be based on 

 records of commercial skipjack landings, an analy- 

 sis of these records is an essential part of this 

 study. 



HAWAII SKIPJACK FISHERY 



The skipjack, or aku, is the most important com- 

 mercial species of fish in Hawaii, both in terms of 

 quantity landed and dollar value. The 11 million 

 pounds caught and sold for $1,260,000 in 1956 con- 

 stituted about 70 percent of the total catch of 

 marine species and 40 percent of the value received 

 by Havraii fishermen during that year. Most of 

 the catch is canned, but a small amount, estimated 

 at less than 10 percent, is sold fresh. 



June (1951) and Yamashita (1958) have de- 

 scribed the fishery in some detail. Since World 

 War II, the skipjack fleet has consisted of approxi- 

 mately 15 to 20 sampans based in Honolulu, with 

 a few boats based at the islands of Kauai, Maui, 

 and Hawaii. A sampan usually carries a crew of 

 8 to 15 men. The fishermen rely on the presence 

 of flocks of wild birds to locate skipjack schools. 

 The fish are caught on pole-and-line after being 

 attracted to the boat by chumming with live bait. 



The fishery is seasonal with large catches gener- 

 ally occurring in the summer and small catches in 

 the winter months. Catches have fluctuated 

 widely in recent years (fig. 1). Tlie skipjack 

 taken weigh from 2 to 30 pounds. The most 

 sought after size is the 17- to 22-pound fish, known 

 to the fishermen as "season fish.'' Brock (1954, p. 



Note. — Approved for publication February 24, 1961. Fishery 

 Bulletin 195. 



96) estimates these to be either in their second or 

 third year of life. The reason for the seasonal 

 fluctuation in the catch appears to be the migra- 

 tion of season fish into and out of the area of the 

 fishery, but the direction and significance of this 

 migration in the life history of the species are 

 largely miknown. 



1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 



FiGUEH 1. — Annual Hawaii skipjack catch, 1948-58. 

 PURPOSES OF THIS STUDY 



The purposes of this study are (1) to examine 

 the i-aw catch data and I lie catch per unit of effort 

 as measures of the apparent abundance of skip- 

 jack; (2) to search the data for differences Ije- 

 tween good and poor years in the fishery; (3) to 

 study movements of skipjack within the fishery 

 during the course of the season ; (4) to examine the 

 distribution of pounds of skipjack caught, catch 

 per unit of effort, total effort, and size composi- 

 tion of the catch throughout the fishery. 



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