SALMON IN THE OCEAN 



Until recently the movements of salmon and their re- 

 lations to the environment in the vast expanse of the North 

 Pacific Ocean were virtually unknown. Their lives were 

 shrouded in mystery once the young fish left rivers and 

 streams on the journey that would end in their return one 

 to several years later as adults. 



Since 1955, however, a store of new information has 

 been gradually acquired during research on the high seas 

 for the INPFC (International North Pacific Fisheries Com- 

 mission). Techniques were developed to classify sockeye 

 salmon as of "North American" or "Asian" origin. Scien- 

 tists demonstrated that North American and Asian stocks 

 intermingle at sea but were unable to define the factors that 

 control fluctuations in the marine distribution of the salmon. 



Knowledge for use in the management of salmon fisheries 

 also has been increased. New facts have been revealed by 

 research on salmon growth and mortality in the ocean, on 

 eflFects of fishing, on physiology of maturation, and on more 

 precise means to identify ages and stocks of salmon; these 

 facts have direct application to eflicient use of salmon stocks. 



DISTRIBUTION AND ENVIRONMENT 



In an eff'ort to relate the distribution of salmon at sea 

 to dynamic ocean characteristics, such as major currents, 

 14 major research cruises were undertaken in the North 

 Pacific Ocean and Bering Sea during 1966-68. The research 

 vessels George B. Kelez and Miller Freeman (figs. 4 and 5) 

 and two charter vessels logged more than 108,000 miles, 

 the equivalent of more than four trips around the world. 

 Along the cruise tracks our scientists fished with gill nets 

 of various mesh sizes (fig. 6) and collected data to sample 

 salmon populations (fig. 7), define ocean domains, and 

 measure biological productivity. 



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FIGURE 4.— The George B. Kelez, a converted military cargo 

 ship, is 176 feet long, has a cruising speed of 11 knots, and 

 carries 6 scientists and a crew of 14. The vessel was named 

 for a scientist from the Biological Laboratory who lost his life 

 in a plane crash while on duty in Alaska in 1954. 



Research on the ocean distribution of salmon is designed 

 primarily to fulfill the obligation of the United States to the 

 INPFC and to measure the effects of foreign fisheries on 

 U.S. salmon stocks. Under provisions of an international 

 agreement, Japan agreed not to fish for salmon east of a 

 provisional line established in 1952 along long. 175° W. Our 

 research has concentrated on predictions of when and where 

 Bristol Bay sockeye salmon ai"e found, how available they 

 are to the Japanese fishery, and what their abundance is 

 inshore. 



