Feeding Habits of Albacore Thunnus Alalunga in the Transition Region of the Central North Pacific
Blackwell Science, LtdOxford, UK FISFisheries Science0919-92682004 Blackwell Science Asia Pty Ltd 704August 2004 843 Feeding habits of albacore H Watanabe et al. 10.1111/j.1444-2906.2004.00843.x Original Article573579BEES SGML FISHERIES SCIENCE 2004; 70: 573–579 Feeding habits of albacore Thunnus alalunga in the transition region of the central North Pacific Hikaru WATANABE,1* Tsunemi KUBODERA,2 Suguru MASUDA3 AND Shigeyuki KAWAHARA1 1National Research Institute of Far Seas Fisheries, Shimizu-Orido, Shizuoka 424-8633, 2National Science Museum, Shinjyuku, Tokyo 169-0073 and 3Shizuoka Prefectural Fisheries Experiment Station, Yaizu, Shizuoka 425-0033, Japan ABSTRACT: The feeding habits of albacore Thunnus alalunga (fork length: 48.9–76.2 cm, n = 132) were examined from late spring to early autumn in relation to its northward migration in the transition region between the subtropical and subarctic fronts in the central North Pacific. Samples were collected at night using surface gill nets or during daytime pole-and-line surveys in 2001 and 2002. During May and June, albacore fed mainly on Japanese anchovy Engraulis japonicus, which accounted for 27.2%, 67.0%, and 45.5% of the total stomach contents by number (Cn), wet weight (WW), and frequency of occurrence (F), respectively, and secondarily on the subarctic gonatid squid Gonatopsis borealis (Cn, 15.8%; WW, 10.8%; F, 28.8%). From July to September, albacore continued to depend on Japanese anchovy (Cn, 48.2–52.8%; WW, 79.9–95.2%; F, 27.8–85.4%). These results corresponded well with the remarkable rebound of the Japanese anchovy stock since the 1990s.
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