HENRY: FALL CHINOOK SALMON 



Alaska 

 BritishColumbia 

 Washington 

 Oregon 

 California 



50 



50 50 



PERCENT 



50 



50 



Figure 7. — Calculated total recoveries (in percent) of general marked Colum- 

 bia River hatchery fall chinook salmon, by age, in different fishing areas, 1961- 

 64 brood years (Columbia River recoveries are shown as the shaded portion 

 of the Oregon recoveries). NS :^ no sample; * = less than 1 percent. 



net fishery (Figure 7). For all ages combined, 

 the recoveries were fairly equally distributed 

 between the British Columbia, Washington, and 

 Columbia River fisheries. 



As mentioned above, the age at recovery for 

 Kalama fall chinook salmon was somewhat dif- 

 ferent than the age at recovery of the other two 

 groups of marked fish. This is more clearly seen 

 in Figure 8 where the calculated total ocean re- 

 covery of special marked Spring Creek, Kalama, 

 and general marked fish (by age) for these four 

 brood years is shown. Thus, for Spring Creek 

 most of the ocean recoveries were as 3-year-old 

 fish (66-83%); Kalama mainly as 3- (21-57%) 

 and 4-year-olds (32-66%); and general marks 

 mainly as 3-year-olds ( 64-73 7r). 



SIZE AND GROWTH 



Not only were the recoveries by age and area 

 diflferent for Spring Creek and Kalama fall chi- 

 nooks, but these fish also experienced diflferent 

 apparent growth patterns. In Figure 9 are 

 shown the average weights, by age and sex, of 

 marked Spring Creek and Kalama fish recovered 

 in the Columbia River gillnet fishery. The Ka- 



lama fall chinooks were generally smaller than 

 the Spring Creek fish at ages 2-4, whereas the 

 Kalama fish were larger at age 5. This change 

 in the relative size of fish from these two stocks 

 of salmon might reflect the selective effects of a 

 more intensive troll fishery on the faster grow- 

 ing, earlier maturing Spring Creek fish, whereby 

 the larger Spring Creek fish are more apt to be 

 caught by the troll fishery at ages 2 and 3. Since 

 data are limited for some of the sex-age cate- 

 gories, I have combined the data for all brood 

 years and both sexes and have completed a von 

 Bertalanffy type growth equation for these two 

 stocks (Figure 10) . The relatively faster growth 

 at the younger ages and the more abrupt slowing 

 down of growth at the older age is evident for 

 the Spring Creek fish. Parameters calculated 

 for Spring Creek were: W ^ = 12.76 kg, ^o = 

 1.02, and k ~ 1.1; for Kalama they were: W ^ 

 = 18.44 kg, to = 0.77, and k = 0.6. These 

 growth parameters clearly detail the growth dif- 

 ferences between these two stocks and would be 

 useful in any future dynamic pool type of analy- 

 sis (Beverton and Holt, 1957) of potential pro- 

 duction from them. 



437 



