FRENCH and DUNN: LOSS FROM HIGH-SEAS GILLNETTING 



USSR 



CANADA 



Figure 7. — Fishing area of Japanese mothership and land- based fishery. 



long. 170°25'E. In recent years the fleet has 

 been changing the gill nets to monofilament 

 netting in lieu of multifilament netting. Our 

 most recent information is that most, if not 

 all, of the catcher boats now use the mono- 

 filament gear. 



Although our experiments on dropouts and 

 fallouts have been conducted on research vessels, 

 the results are applicable to fishing practices 

 as carried out by the mothership fleet. The 

 webbing for the gill nets used by our research 

 vessels originated from Japan, and construction 

 of the gill nets was generally copied from the 

 construction of Japanese gear. The leadline of 

 the Japanese gear has heavier cordage and is 

 slightly shorter than the corkline, whereas in 

 the U.S. gear the corkline is slightly shorter 

 than the leadline and is of heavier cordage; 

 therefore, while the gear is soaking and during 

 the hauling, the tension is on the leadline in 

 Japanese commercial gear and on the corkline 

 in U.S. research gear. The mesh sizes of 114 

 mm and 133 mm, as used by our research ves- 

 sels for capturing maturing salmon and the 



larger immature salmon were similar in size 

 to the mesh sizes (121 and 130 mm) of the com- 

 mercial nets of the fishing fleets. The modal 

 selection length for 114-mm and 121-mm meshes 

 are 53 cm and 56 cm, respectively, and for 130 

 mm and 133 mm, 60 and 62 cm, respectively, 

 which is a very slight disparity in selection 

 lengths (Fukuhara, 1971). 



Salmon catches by the Japanese mothership 

 fleet have ranged from about 19 to 26.5 million 

 fish and have averaged about 22 million salmon 

 annually for 1960 through 1968 (International 

 North Pacific Fisheries Commission, 1965- 

 1968). An annual estimated average of about 

 2.5 million sockeye salmon (maturing and im- 

 mature) of Bristol Bay origin have been taken 

 by the mothership fishery; the catch has 

 ranged from approximately 0.3 to 7.2 million 

 fish for 1956-69 (Fredin and Worlund).« Loss 



^ Fredin, R. A., and D. D. Worlund. 1972. Eslimales 

 of the catches of sockeye salmon of Bristol Bay origin by 

 the Japanese mothership salmon fishery, 1956 to 1970. 

 Northwest Fish. Cent., Natl. Mar. Fish. Serv.. NOAA, 

 Seattle, Wash., 82 p. [Unpubl. Manuscr.] 



871 



