PEARCY: ALBACORE OCEANOGRAPHY 



fishes, and Sergestes were the most common 

 organisms in their stomachs. Only one saury 

 was identified. Examination of the feeding 

 habits of bait-caught albacore during the late 

 summer would be of particular interest. Absence 

 of saury from these fish would suggest that 

 saury was not available to albacore for the 

 remainder of the season in this region off 

 Oregon, and albacore fed on alternate food 

 organisms from subsurface waters. These 

 changes in the behavior of albacore show 

 similarities with the schooling and foraging 

 behavior of bluefin tuna, Thunnus thynnus, 

 schools off Baja California noted by Scott and 

 Flittner (1972). They found that the occur- 

 rence of jumping and boiling schools on the 

 surface was related to foraging on baitfish, 

 whereas subsurface schools, which produced 

 the largest purse seine catches per set, fed 

 more on red crab, Pleuroncodes pkuiipes. 



A major conclusion of this paper is in accord 

 with the hypothesis that the geographic range 

 of tuna is established by temperature but food 

 supply is largely responsible for distributions 

 within this range (Blackburn, 1964; 1969 

 Nakamura, 1969). If this hypothesis is correct, 

 it follows that accurate predictions of albacore 

 concentrations in time and space must consider 

 abundance and availability of forage organisms. 

 Moreover, the depth distribution of the preferred 

 albacore food will have pronounced influence 

 on the relative successes of jig and bait fisheries, 

 as the 1970 season off Oregon demonstrated. 



ACKNOWLEDGMENTS 



I thank D. F. Keene for helping to analyze 

 the data; L. H. Hreha, W. L. Craig, and R. M. 

 Laurs for supplying catch data; G. A. Flittner, 

 R. W. Owen, D. A. Panshin, and R. M. Laurs 

 for their comments on the manuscript; the 

 U.S. Air Force 304 ARRS Squadron in Port- 

 land, Oreg. and the U.S. Coast Guard Station 

 in Port Angeles, Wash, for providing remote 

 sensing flights; and the skippers of fishing 

 boats for keeping albacore logs. This research 

 was supported by the U.S. Naval Oceanographic 

 Office (Spacecraft Oceanography, Contract N6 

 22306-70-C-0414). the former Bureau of Com- 



mercial Fisheries (Contract No. 14-17-0002- 

 333) and the National Oceanic and Atmospheric 

 Agency Institutional Sea Grant (2-35187). 



LITERATURE CITED 



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Blackburn, M. 



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