Landings of Billfishes in the Hawaiian Longline Fishery 



HOWARD O. YOSHIDA' 



ABSTRACT 



The landings of the Hawaiian longline fishery are dominated by the tunas. During 1964 to 1967, the 

 tunas, by weight, made up an average of 66% of the catch, whereas the marlins and swordfish, Xiphias 

 gladius, comprised about 34%. The catch of billfishes is composed of the striped marlin, Tetrapturus 

 audax, blue marlin, Makaira nigricans, black marlin, M. indica, sailfish, Istiophorus platypterus, 

 shortbill spearHsh, T. angustirostris, and swordfish. 



The annual landings of blue marlin ranged between 47 and 366 metric tons during 1952 to 1970. The 

 annual landings of striped marUn fluctuated between 93 and 228 metric tons during the same period. The 

 blue marlin dominated the catch from 1952 to 1961. Subsequent to 1963, the billfish catches have been 

 dominated by the striped marlin. 



The monthly landings and the monthly catch rates of blue marlin and striped marlin showed similar 

 trends. The monthly landings of striped marlin, however, showed greater fluctuations than the monthly 

 catch per unit of effort. This was attributed in part to a change in the size composition of striped marlin in 

 the third quarter. 



The Hawaiian longline fishery has been described 

 in the past primarily from the viewpoint of a fishery 

 for deep-swimming tunas, usually yellowfin tuna, 

 Tliiinniis alhacares. and bigeye tuna, T. ohesus. 

 June (1950), Otsu (1954), Shomura (1959), and Hida 

 (1966) all have made studies on this fishery as it 

 related to the tunas. One of the exceptions is a paper 

 by Strasburg (1970) on the billfishes of the central 

 Pacific Ocean, in which he briefly discussed the 

 billfishes landed in Hawaii. This report considers the 

 Hawaiian longline fishery as it relates to the bill- 

 fishes, particularly the blue marlin, Makaira nigh- 

 cans, and the striped marlin, Tetrapliirus audax, 

 primarily during the period from 1963 to 1970. 



The data used for this report came primarily from 

 two sources. The billfish landing data through 1968 

 were obtained from the Fishery Statistics of the 

 United States. The landing data for 1969 and 

 1970 and fishing trip data are from the files of 

 NMFS (National Marine Fisheries Service), Hono- 

 lulu, Hawaii. Billfish weight and sex data from 1964 

 to the middle of 1970 were collected at the Honolulu 

 auction markets by samplers from our Laboratory. 



' NOAA, National Marine Fisheries Service, Southwest 

 Fisheries Center, Honolulu Laboratory, Honolulu, Hawaii 

 96812. 



DESCRIPTION OF THE FISHERY 



The Hawaiian longline fishery is the only Ameri- 

 can fishery employing the longline method of fishing 

 (Shomura, 1959). The history and description of the 

 fishery are given by June (1950) and Otsu (1954). 



Typical Hawaiian longline boats evolved from the 

 Japanese sampan-type, live-bait boat (June, 1950). 

 They are characterized by a narrow bow, angular 

 lines and a low freeboard aft. The overall length of 

 these vessels ranges from 8.53 to 18.90 m (28 to 62 ft). 

 All except one of the vessels in the Hawaiian fishery 

 have wooden hulls. The length of a fishing trip aver- 

 ages 8 or 9 days for a Honolulu-based vessel and the 

 majority of the trips are made within sight of the main 

 Hawaiian Islands (Shomura, 1959). 



The number of longline boats in the Hawaiian fleet 

 has steadily declined over the years. In 1952 there 

 were 42 boats in the Hawaiian fishery. In 1964 the 

 number was down to 31 and in 1970 to 20. Although 

 the number of boats in the fishery has been declining, 

 one new boat was recently added to the longline 

 fleet. This vessel has a steel hull and a refrigerated 

 fish hold, and has an extended cruising range. The 

 vessel began operations in July 1969 and has fished 



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