Small mother ships of 400 to 800 gross tons are able 

 to carry only one portable catcher boat, but the larger 

 2,000- to 3,000-ton mother ships carry six catcher 

 boats. The portable catcher boats measure about 15 m 

 in length (Yoshida, 1966). To decrease the weight of 

 the portable boats, recent constructions have been of 

 fiber-reinforced plastic (FRP). The weight of a FRP 

 boat is about 13 tons, or approximately two-thirds the 

 weight of former catcher boats (Kazama, 1967). 



Significant advances have also been made in 

 preserving the catch of high-quality sashimi fish. 

 Many vessels are equipped with refrigeration equip- 

 ment capable of preserving the catch at very low 

 temperatures of -40° to — 45°C. In this way, the 

 vessels are able to deliver fish in excellent condition 

 and as a result, billfish prices have increased greatly 

 in the Japanese market. 



In addition, there have been advances in 

 automating ship operations, fishing gear, and other 

 equipment. Almost all longliners are equipped with 

 fish detectors. Living conditions on the ships have 

 also been improved considerably, and many vessels 

 are now equipped with air conditioning for the crew's 

 comfort (Katsuo-Maguro Nenkan, 1969). 



Harpoon vessels are constructed with an extended 

 prow where the harpooner is stationed. These vessels 

 are constructed of wood, and range in size from about 

 10 to 40 tons. Billfishes taken by these vessels are kept 

 in ice for delivery to the market. 



5.2 Fishing Areas 



5.21 General geographic distribution 



The longline fishery now virtually covers the entire 

 distribution of the species (see 2.1 and 2.22). The ma- 

 jor sport fishing areas are southern California, Mex- 

 ico, Panama, Ecuador, Peru, Chile, Hawaii, Tahiti, 

 Fiji, New Zealand, Australia, and East Africa (not 

 listed in order of importance). 



5.22 Geographic ranges 



See also 5.41. 



Longlining is carried out across the high seas to 

 within 5 miles of coastlines in places. The sport 

 fishery is generally restricted to within about 75 miles 

 of coastlines with the bulk of the fishing much closer. 



The greatest fishing pressure is exerted in the North 

 Equatorial Current in the Pacific and western Indian 

 oceans, in the Kuroshio and Kuroshio extension, in 

 the North Pacific Gyral northeast of the Hawaiian 

 Islands, in the South Equatorial Current from about 

 long. 90° to 140°W, and also off Mexico and Ecuador. 



Regarding the development of the Japanese 

 longline fishery, Suda and Schaefer (1965) report that 

 prior to about 1952 the fishery was confined to the 

 western and central Pacific. After this date it expand- 

 ed into the Indian Ocean extending west of long. 80°E 

 in 1954 and throughout the Indian Ocean by the end 



of 1955. In the Pacific, the fishery expanded eastward 

 between lat. 10°N and lat. 10°S reaching 130°W by 

 late 1956 and long. 85° W by 1961. After 1963 the 

 fishery in the eastern Pacific expanded rapidly 

 poleward, the northward expansion being primarily 

 for striped marlin (Kume and Joseph, 1969a). 



The fishing grounds for the Japanese harpoon 

 fishery are located in the waters of Sanriku (off 

 northeast of Honshu), around Izu, and East China 

 Sea. 



5.23 Depth range 



Little has been written regarding fishing effort by 

 depth range. Merrett (1968a) reports almost half of 

 the striped marlin caught during experimental 

 longlining off East Africa were caught over less than 

 1,000 fathoms even though most of the effort was ex- 

 pended beyond this depth contour. 



5.24 Conditions of the grounds 

 See sections 2.1, 2.2, and 2.3. 



5.3 Fishing Seasons 



For sections 5.31, 5.32, and 5.33 see section 2.22. 



The fishing season for the Japanese harpoon fishery 

 in the waters of the Sanriku fishing ground extends 

 from June to November with the peak occurring from 

 July through September; in the Izu area from 

 December to August with its peak from February 

 through April; and in the East China Sea from 

 December to February. 



5.4 Fishing Operations and Results 



5.41 Effort and intensity 



Type of unit of effort: Detailed data on fishing effort 

 and catch in the Japanese tuna longline fishery are 

 published in the "Annual report of effort and catch 

 statistics by area on Japanese tuna longline fishery" 

 by the Research Division, Fisheries Agency of Japan. 

 Fishing effort is reported in terms of number of 

 operations and number of hooks fished; catch is 

 reported in terms of number of fish. The statistics are 

 reported on a monthly basis by 5° units. 



Since 1967, Taiwan has also begun to publish data 

 from their tuna longline fishery, following the same 

 format as the Japanese publication. The Taiwan data 

 are published annually in "Report on survey of 

 production and marketing of Taiwan's tuna longline 

 fishery" by the Taiwan Fisheries Bureau. Publication 

 of effort and catch statistics of the Korean longline 

 fishery started in 1970 in "Yearbook of catch and ef- 

 fort statistics on Korean tuna longline fishery" issued 

 by the Office of Fisheries, Korea. 



Landings per unit of fishing effort: As noted above, 

 the catch statistics are reported in terms of numbers 



152 



