Table 7. — Some examples of Japanese tuna longline gear. (From Suda and Schaefer, 1965.) 



of the float line and branch line should not exceed 30 

 m. 



As for the amount of gear fished per day, Yoshida 

 ( 1966) reported that "Vessels of 39 to 99 gross tons fish 

 210 to 355 baskets; vessels 100 to 190 gross tons fish 

 355 to 400 baskets; and vessels 200 to 500 tons fish 400 

 to 450 baskets." Suda and Schaefer (1965) reported 

 that Japanese vessels in the eastern Pacific fished an 

 average of 2,000 hooks (about 400 baskets) per set. 



The basic construction of the longline gear has 

 remained unchanged over the years. However, due to 

 manpower problems some effort has been directed 

 towards developing laborsaving devices in longlining. 

 Two examples are the reel-type and tub-type of 

 longlining. 



In the reel -type, the mainline is continuously reeled 

 onto a drum, while in the tub-type, the retrieved line 

 is coiled into a large tub. Important advances in addi- 

 tion to the line hauler, include the "slow-conveyor" 

 (for line setting and line hauling), the "guide stand" 

 and "guide roller" (for leading line), gear-transport- 

 ing conveyor system, line-winder system, etc. In using 

 these methods, the branch lines are joined to the 

 mainline by the use of snaps (Katsuo-Maguro 

 Nenkan, 1969). 



The principal bait used in longlining is frozen 

 Pacific saury, Cololabis saira. Squid is also commonly 

 used. Mackerel, Scomber sp., as well as mackerel 

 scad, Decapterus sp., have been used as alternate 

 bait. In addition, experiments are underway to utilize 

 silver carp, Hypophthalmichthys molitrix, as well as 

 artifical preparations (e.g., infused with extracts of 

 saury) as longline bait. 



Depending on the location, certain baits have been 

 reported to have advantages in catching billfishes. For 

 instance, in the East China Sea fishing grounds, live 

 mackerel were believed effective and were used exten- 

 sively. However, Furukawa et al. (1957) reported that 

 using live or dead mackerel did not significantly affect 



the catches of white marlin (= black marlin), striped 

 marlin, and broadbill. 



The main piece of equipment in the harpoon fishery 

 is the harpoon itself. The harpoon pole of oak is about 

 4 m long and at its tip is a three-pronged iron piece 

 about 7 mm in diameter. The detachable harpoon of 

 steel about 10 cm in length, connected to about 100 m 

 of line, is placed over this iron tip. Recently the elec- 

 tric harpoon has been used in order to kill the fish 

 quickly. When the harpoon enters the fish, a wire dis- 

 tributed along the harpoon line is charged with elec- 

 tricity. 



5.12 Boats 



The longline vessels fishing in the Indian and 

 Pacific oceans for striped marlin are largely those 

 from Japan. Other vessels are from Taiwan and 

 Korea. 



The details on the construction of longline vessels 

 are given by Kanasashi (1960) and by Yoshida (1966). 

 There are two types of longline vessels: those that use 

 longline exclusively and those that use both longline 

 and pole and line. The holds on longline vessels are 

 not divided into small compartments to carry live 

 bait. Thus, the hold space in the longliners is 20% to 

 40% greater than in the combination vessels. 



Longline vessels are constructed of wood or steel; 

 those larger than 100 gross tons are usually con- 

 structed of steel. Most of the longliners are 250 to 350 

 gross tons; at this stage of the fishery they appear to 

 be the most economical and efficient size to operate. 

 The specifications of typical longliners of this size 

 class and those of some typical combination vessels 

 are given in Yoshida (1966). 



Other than the independently operating vessels, 

 there is the mother ship operation in which several 

 catcher boats are transported on the deck of a mother 

 ship to the fishing grounds. 



151 



