356 



Fishery Bulletin 93(2), 1995 



• 60°N 



46 

 4?< 



WA 



45 



43 



49 so •<&> 



51 • 



52 



42 "' «23r *. • 



••5-5 56 



-50°N 



Figure 1 



Survey stations of Japan-U.S. cooperative longline surveys in Alaskan waters ( 1980-89). Surveys were not conducted in the Bering Sea 

 (B-II, B-III, and B-IV) during 1980 and 1981 seasons. (•) = stations where killer whales, Orcinus orca, were not encountered; (A) = 

 stations where whales were encountered (stations 10, 19, and 83 killer whales were observed but no depredation occurred). B = Bering 

 Sea, WA = Western Aleutian Islands, EA = Eastern Aleutian Islands, SH = Shumagin Islands, CH = Chirikof Island, KO = Kodiak 

 Island, YA = Yakutat, SE = Southeast Alaska. 



tification of species and size offish consumed by killer 

 whales; and 4) quantification of the amounts of 

 longline catch lost to killer whales. 



Materials and methods 



Stations for the Japan-U.S. longline research sur- 

 vey in Alaskan waters were established by the Na- 

 tional Research Institute of Far Seas Fisheries, Fish- 

 eries Agency of Japan, and the National Marine Fish- 

 eries Service (NMFS), Alaska Fisheries Science Cen- 

 ter. In 1980 and 1981, 76 stations were fished, exclud- 

 ing areas B-II, B-III, and B-IV (29 stations) in the 

 Bering Sea (Fig. 1). Beginning in 1982, the number of 

 stations (which represent 11 major fishing areas) in- 

 creased to 108 to include the additional Bering Sea sta- 

 tions (Sasaki, 1985; Fig. 1). Surveys were conducted 

 between May and September each year (1980-89). 

 Weather permitting, one station was fished per day. 



The research vessels selected for the surveys were 

 chartered Japanese commercial longline vessels that 



had been used for previous sablefish and Pacific cod 

 fishing operations in the North Pacific Ocean. The 

 bottom longline was 16 km long and consisted of 160 

 "hachis" (skates). Each hachi was 100 m long and 

 contained 45 hooks which were spaced 2 m apart. 

 Gangion lengths were 1.2 m. Each hook was baited 

 with squid (total number of hooks=7,200). The hook 

 (standard type: Tara [=cod] no. 18) was 74 mm in 

 length and 21 mm in width. The depth at which fish 

 were caught was estimated by measuring the depth 

 of water under the vessel with an echo sounder at 

 every fifth hachi. The catch was recorded by estimat- 

 ing the numbers of species or species groups for each 

 hachi. The total catch of the major species was 

 weighed to the nearest gram. Total length (TL) or 

 fork length (FL) was measured for each species to 

 the nearest millimeter. Details of the survey meth- 

 ods and longline gear are described in Yano 4,5 . 



4 Yano, K. 1989. Japan-U.S. joint survey for stock assessment of 

 sablefish and Pacific cod resources in 1988. Report of the North- 

 ern Groundfish Section, Japan Scientific Council on the 



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