change in fishing methods must prove of decided superiority over existing 

 techniques on an actual production basis o Minor improvements are being 

 introduced by fishermen, and radical types of gear are being tested by 

 various Governmental research agencies. 



The only improvement made in purse seines during the past five 

 years is the use of chain to replace lead lines. A cheap grade of linen 

 netting was used experimentally in 19^0 in the hope of making a lighter 

 and stronger seine but the material would not stand upo High grades of 

 linen are too expensive to compete with cotton as netting material for 

 tuna seines^ The life of a tuna seine is relatively short because of 

 deterioration in the tropics and the distortion of the netting due to 

 the heavy catches o It is possible that plastic or nylon netting may 

 prove superior to cotton but no testing program is in existence now as 

 far as can be determinedc 



Results of experimental gill netting for albacore by the Service 

 vessel John Ne Cobb in 1950 were encouraging (Powell, Alverson and 

 Livings tonej 1952)3 but the poor runs of albacore in the Pacific North- 

 west the following two years prevented further large-scale experiments 

 with gill nets « Trials of gill nets in Hawaiian waters by the Pacific 

 Oceanic Fisheries Investigation met with little success in catching tuna. 

 This was believed to be at least partly due to the extremely clear water 

 in the area. It has not been demonstrated as yet that gill nets will 

 catch any species of tuna as consistently or efficiently as the standard 

 types of gear now in use. Perhaps gill nets may be used as auxiliary 

 gear -virfiich can be set while the tuna boat is drifting at nighto Over- 

 all catches might be increased in this manner, but at the moment there 

 is no indication that gill netting will replace ar^y other gear or will 

 be used exclusively by any tuna boats o 



Long-line gear^ developed and used extensively by Japanese tuna 

 fishermen, has been under test by the Pacific Oceanic Fishery Investi- 

 gations staff of the Fish and Wildlife Service in the central Pacific 

 for several years o These tests have proved that tuna can be taken with 

 long line over a wide area of Pacific equatorial waters at rates as 

 good or better than prevail in the Japanese tuna fishery,, An experiment 

 with a Pacific coast purse seiner, the Cavalieri , using long -line gear, 

 was successful in taking a full load of tuna. However, the fish were 

 of large size, and much of the catch was discarded because of dis- 

 coloration o Long line has certain advantages over other gear in that 

 no live bait is needed „ it can be handled in weather too rough for 

 seining, and it does not require siu*face observation of the school as 



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