FISHERY BULLETIN: VOL. 71, NO. 2 



that groups of fish at each station were com- 

 posed largely of transitory groups. Interstation 

 turnover probably resulted from irregular move- 

 ments of fish along the shoreline and seaward 

 migration, in response to such factors as physio- 

 logical stimuli, high river discharge, rising water 

 temperature, and daily and weekly fluctuations 

 in regulated water levels. 



The combined mean lengths of fish collected 

 at upper and lower stations provide a clearer 

 picture of growth in relation to season (Figure 

 7). The slight curvilinear relationship reveals 

 an increase in growth rates under warming 

 temperature regimes in June and July. 



Length -Weight Relationship 



Although lengths of juvenile chinook salmon 

 varied randomly between and within samples, 

 the length-weight relationship for fish of equal 

 size is a relatively consistent parameter. Fur- 

 thermore, the relationship is characteristic of 

 a given habitat and may indicate the adequacy 

 of all synecological conditions leading to fish 

 growth and development in that environment. 



Preliminary statistical comparison of length- 

 weight relationships by a nonlinear least- 

 squares-fitted power function revealed no sig- 

 nificant differences between stations. Conse- 

 quently, the length-weight relationship of 

 juvenile chinook salmon at Hanford was cal- 



culated by the standard regression equation 

 Log Y = Log A + b Log X. The regression 

 was slightly curvilinear throughout the 40 to 

 80 mm size range (Figure 8). The computed 

 values transform the equation to Log Y = 

 -12.52 + 3.31 LogX. 



Coefficients of Condition 



In fisheries biology, the coefficient of condi- 

 tion is used primarily as an aid in determining 

 the general physical status of fish stocks in 

 different environments. The standard equation 

 is: 



K 



1^(10^) 

 T3 ' 



where K is the coefficient of condition, W is 

 the weight of the fish in grams, L is the 

 length of the fish in mm, and the factor 10'' 

 brings the value of K near unity. 



Calculations were made on the basis of 

 juvenile chinook salmon in 10-mm size groups 

 from all primary stations combined (Table 5). 

 K was lowest (1.08) for the 36-45 mm size 

 group, i.e., the smallest fish emerging from 

 the gravel in early spring and beginning to 

 feed at low river temperatures. K values in- 

 creased to the range of 1.3 to 1.4 for the 

 larger size groups. Indices of FI for the 



^■UPPER STATIONS (n-237) 

 I I LOWER STATIONS (n = 459) 



RICHLAND TEMPERATURE 



40 



15 



- 5 



MARCH 



APRIL 



Figure 7. — Growth of juvenile chinook salmon at upper and lower stations, March- 

 July 1969, in relation to Columbia River temperatures. 



396 



