Fisher and Pearcy: Distribution, migration, and growth of Oncorhynchus tshawytscha 



285 



100 



5 10 15 20 25 30 35 40 



Distance offshore (km) 



B 



100 



80 



o 60 



40 



20 



<130 mm FL 



15 20 25 30 



Surface salinity (°/ 0O ) 



100 



80 



60 



ro 40 



20 



s 130 mm FL 



10 12 14 16 



Surface temperature ( C) 



18 



Figure 3 



Cumulative percentages of small (<130 mm FL), 

 large (>130 mm FL) and all lengths of chinook 

 salmon, Oncorhynchus tshawytscha, caught at 

 various (A) distances offshore (km); (B) sea-sur- 

 face salinities (%>); and (C) temperatures (°C) for 

 all months and years of sampling combined. 



R. spring chinook salmon), and five were age-0.1 fish 

 from coastal Oregon and California hatcheries (two 

 Siuslaw R. fall, one Elk R. fall, one Rogue R. fall, 

 and one Trinity R. (Klamath R. system) fall chinook 

 salmon). The two farthest northward migrations 

 were made by an age- 1.0 spring chinook salmon from 

 the Umpqua River, Oregon, caught 481 km to the 

 north off northern Washington in June 1985, and by 

 an age-0. 1 fall chinook salmon from the Trinity River, 

 California, caught 317 km to the north in May 1981. 



Speed of migration 



Average net migration rate of CWT age-1.0 Colum- 



bia River juvenile chinook salmon between rkm 75 

 and their ocean capture locations was 4.1 kmd -1 

 (range 1.1-14.2 kmd 1 , «=31; 1981, 1982, and 1983 

 data combined). This net migration rate was equiva- 

 lent to 0.3 body lengths-sec x (where body length is 

 the average between the mean length of the CWT 

 group at rkm 75 and the length of the individual fish 

 at capture in the ocean). 



Growth of juvenile chinook salmon 



Estimated mean growth rates of age-1.0 CWT Co- 

 lumbia River juvenile chinook salmon between hatch- 

 ery release and capture in the ocean and between 



