considerably. Also, feeding habits probably 

 change with the size and increasing maturity 

 of the fish. 



The true extent of feeding selectivity 

 of the salmon cannot be understood until a 

 more comprehensive understemding of plankton 

 populations is reached. No positive rela- 

 tionship between the animals found in stom- 

 ach contents and plankton samples has been 

 established (Allen, 1956; Nakai and Honjo, 

 19^^i Seelinger, personal communication). 



At present, extensive research is 

 being carried out at this laboratory, using 

 a 6-food model of the Isaacs -Kidd midwater 

 trawl towed at speeds ranging from 5 to 

 about 8.5 knots. The mesh sizes in the net 

 are such that both fish and plankton are 

 caught in the same haul. Preliminary 

 analyses of the stcxnach contents of fish 

 caught In these hauls as compared with the 

 plankton caught in the hauls show a high 

 correlation. It is possible that the 

 Isaacs -Kidd trawl will be a satisfactory 

 device for sampling the food of the salmon. 



Acknowledgements 



Appreciation is expressed for the 

 assistance of Dr. Richard H. Fleming and 

 Mr. Phillip Seelinger of the Department of 

 Oceanograhhy, University of Washington; 

 Mr. C. E. Atkinson of the Pacific Salmon 

 Investigations, U. S. Fish and Wildlife 

 Service; and Dr. Clarence Shoemaker and 

 Dr. Thomas Bowman of the U. S. National 

 Museum. 



Literature Cited 



Allen, George H. 



1956. Notes on the relationship between 

 plankton sampling and the food of 

 the Pacific salmon. University 

 of Washington, Department of 

 Oceanography, Fishery Report No. 

 3. 36 pp. (mimeographed) 



Bamaby, J. T. 



1952. Offshore fishing in Bristol Bay 

 and Bering Sea. U. S. Dept. of 

 the Interior, Fish and Wildlife 

 Service, Specieil Scientific 

 Report--Fisheries No. 89. 30 pp. 



Fukuhara, F. M. 



1953. Japanese 1952 North Pacific Sal- 

 mon-Fishing Expedition. U. S. 

 Dept. of the Interior, Fish and 

 Wildlife Service, Commercial 

 Fisheries Review, 15(2): 1-17- 



Nakai, Z. , and K. Eonjo 



195^' A preliminary report on surveys 

 of plankton and salmon stomach 

 contents from the North Pacific, 

 1952. Japan, Fisheries Agency, 

 Min. Agric. and Forest., Tokai 

 Reg. Fish. Res. Lab., Spec. Publ, 

 No. 3: 6-12. 



Redfield, Alfred C. 



191+1. The effect of the circulation of 

 water on the distribution of the 

 calanoid community in the Gulf of 

 Msiine. Biological Bulletin LXXX 

 (1): 86-110. 



Tanonaka, G. K. 



1955. Cruise of the M. V. Mitkof, 2k 

 July - 5 October 1955- U. S. 

 Dept. of the Interior, Fish and 

 Wildlife Service, Seattle, 

 (Typewritten report). 



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