Ocean Distribution of Stocks of Pacific Salmon, 



Oncorhynchus spp., and Steelhead Trout, 



Salmo gairdnerii, as Shown by Tagging Experiments 



Charts of Tag Recoveries by Canada, Japan, and 

 the United States, 1956-69 



ROBERT R. FRENCH,' RICHARD G. BAKKALA,' and DOYLE F. SUTHERLANDi 2 



ABSTRACT 



Extensive tagging experiments by member nations of the International North Pacific Fish- 

 eries Commission — Canada, Japan, and the United States — have been conducted in offshore 

 waters of the North Pacific Ocean to investigate the ocean distribution of stocks of Pacific 

 salmon, Oncorhynchus spp. This effort has resulted in the recovery of 15,215 tags including 

 steelhead trout, Salmo gairdnerii, from inshore and high-seas areas. To provide a reference by 

 which the offshore distribution of the various stocks can be readily seen as shown by tagging 

 results through 1969, the tagging locations at sea are illustrated for each species and recovery 

 area. 



INTRODUCTION 



The Canadian National Section of the International 

 North Pacific Fisheries Commission (INFPC) provid- 

 ed a list (Aro, Thomson, and Giovando 1971a, 1971b)' 

 of all tag recoveries of Pacific salmon, Oncorhynchus 

 spp., and steelhead trout, Salmo gairdnerii, reported 

 by the three member nations of the Com- 

 mission — Canada, Japan, and the United States. This 

 impressive listing of 15,215 tag recoveries includes 

 basic biological data for each fish and lists recoveries 

 by areas and subareas of the Asian and North 

 American continents and also by oceanic areas of the 

 North Pacific Ocean, Bering Sea, Okhotsk Sea, and 

 Sea of Japan. The extremely valuable and useful 

 listing has prompted us to prepare charts showing the 

 tagging locations on the high seas of returns to the 

 various inshore areas. The atlas will provide a 

 reference by which the high-seas distribution (as 



'Northwest Fisheries Center, National Marine Fisheries Service, 

 NCAA, 272.5 Montlake Boulevard East, Seattle, WA 98112. 



'Present address: Northeast Fisheries Center Panama City 

 Laboratory, National Marine Fisheries Service, NOAA, Panama 

 City, FL 32401. 



'Aro, K. v., A. Thomson, and D. P. Giovando. 1971a. Re- 

 coveries of salmon tagged offshore in the North Pacific Ocean by 

 Canada, .Japan, and the United States, 1956 to 1969. Fish. Res. 

 Board Can., Manuscr. Rep. No. 1147, 493 p. 



Aro, K. v., A. Thomson, and D. P. Giovando. 1971b. Summaries 

 of salmon tag recoveries in North Pacific coastal and high seas areas 

 from salmon tagging in INPFC Statistical Areas in the North 

 Pacific Ocean by Canada, .Japan, and the United States, 1956 to 

 1969. Fish. Res. Board Can., Manuscr. Rep. No. 1148, 641 p. 



shown by results from tagging up to 1969) of any of the 

 several species and many stocks of Asian and North 

 American salmon and steelhead trout can be quickly 

 determined by examination of the appropriate figure. 



Application of the tag and recovery method to the 

 identification and distribution of salmon and 

 steelhead trout stocks on the high seas has as its basis 

 the strong tendency of the fish to return to their home 

 stream to spawn. When a fish is caught in coastal or 

 inland waters in an advanced state of sexual maturi- 

 ty, it is assumed to have originated from that area. 

 The possibility of individual fish straying to other 

 areas or being intercepted enroute to its home stream 

 cannot be fully discounted. Such instances are be- 

 lieved to be few in number and probably have little 

 effect on the general pattern of distribution revealed 

 by the data. 



The origins of Pacific salmon and steelhead trout 

 tagged offshore and recovered offshore are not known. 

 They are included as added information on the spatial 

 distribution of each species on the high seas. 



The oceanic distribution of the various stocks as 

 revealed by the recovery of tagged fish is based solely 

 on their location (within 1° lat. X 1° long.) at the time 

 of tagging. Although their spatial movement prior to 

 tagging and subsequent to tagging until time of recap- 

 ture is not known, a general profile of the oceanic dis- 

 tribution of the major stocks may be constructed from 

 the recovery data. For some stocks sufficient numbers 

 of fish were recovered from tagging over broad areas to 

 show progressive changes in population density from 

 high to low abundance; reliable conclusions, however. 



