HENRY: FALL CHINOOK SALMON 



- 3 



•C + 



+ 1.0 



SPRING CREEK 

 B 



16 



o. 12 



J L 



KAL AMA 

 B 



H.O 



+ 0.5 



I - 



- 



-0.5 - 



20 



16 



' 12 



4- 



J 1 L 



to 



w/3 (kg) 



2 4 6 



AGE (YEARS) 



2 4 6 



AGE (YEARS) 



Figure 10. — Successive stages of fitting Spring Creek and Kalama Hatchery fall 

 Chinook salmon weight data from Figure 8 to the von Bertalanffy growth equation. 

 Part A shows the relation between average weight at age t and age i + 1 — point 

 on the dotted line where Wf/i = w^hf + i is an estimate of W ^Vi. Part B shows the 

 relation between age and a logarithmic function of the weight used to estimate 

 the value of k (i.e., the slope). Part C shows the calculated growth curve based 

 on the values computed from Parts A and B. 



want to analyze a part of the model, the part 

 dealing with the ocean and river fisheries, to 

 show the calculated effect the troll fishery has 

 on total yield for a particular brood year. In 

 these analyses, I have used data developed for 

 the 1961 and 1962 brood years for the Spring 

 Creek and Kalama fall chinooks, based on studies 

 by Cleaver (1969) and Henry (1971), respec- 

 tively. Where there were some data missing 

 for the 1962 brood Spring Creek fish, I used 1961 

 data. The starting point for the analyses is at 

 age 1+ in Figure 11. 



It is apparent from Figure 11 that given Fu 

 Mi, Pi, and RF,, as well as data on average 

 weights of fish at each age, total yields from the 

 ocean and river fisheries for a given number of 

 recruits (R) can be calculated. Henry (1971) 

 gives estimates of Fi and Pi for various values 

 of Mi as well as values for RFi for 1961 brood 

 Spring Creek and Kalama fish and 1962 brood 

 Kalama fish. Lack of river recoveries of 5-year- 

 old fish prevented estimates of these values for 

 1962 brood Spring Creek chinook salmon. Henry 

 also 'ists average weight data, by age, for both 



439 



