TABLE 1 



Mortalities in the 1960 6-week 



starvation lot by weekly interval 



Week 



Mortality 



13 

 



1 



1 



4 



11 



^feeding resumed) 



9 

 10 

 11 

 12 

 13 

 14 



14 

 7 

 1 

 

 

 

 

 



Total 



52 



each sample. Condition factor is widely used 

 by fishery biologists as an expression of rela- 

 tive robustness or "degree of well being" of 

 the fish. Condition factor was not calculated 

 for the initial 1959 test lot sample due to an 

 oversight in which lengths were not recorded. 

 In table 2 the initial mean weight of the control 

 lot (3.94 grams, n. = 84) is significantly higher 

 than that of the test lot (3.41 grams, n. = 117). 

 This unexpected difference may be due to 

 (1) size selectivity in the dip net method 

 used to halve the original sample of 1,200 

 fish, (2) a sampling error, or (3) a recording 

 error. In any case, we do not feel that this 

 discrepancy materially affected the overall 

 experimental results. 



With few exceptions, fish gained weight when 

 fed and lost weight when starved in 1959. We 

 initially suspected that two of these exceptions, 

 the weight loss by the fast growing control 

 and 2- week test lots from September 11-24, 

 might be mainly due to the previously 

 described irregular feeding during that period. 

 Subsequent examination of the 1960 data (table 

 3 and fig. 6) revealed the same type of pattern 

 (a growth slowdown in some lots and an actual 

 loss of weight in others) after September 15 



8-week starvotion lot 



6-week storvolion lot 



4-week starvotion lot 



2-week starvation lot 



1.0 



oe;r 



6 ^ 



1.0 ^ 

 08 5 



est 



8 „ 

 0.6 8 



7-17 7-30 8-14 8-28 9-|l 9-24 

 SAMPLING DATE 



Figure 5.--Growth rates of the various lots in the 1959 

 experiment to mark the scales of sockeye salmon 

 fingerlings by short periods of starvation. 



of that year despiteregular feeding. It appears, 

 then, that growth slows naturally after mid- 

 September, particularly in the lots With the 

 higher condition factors. This slowdown in 

 naturally occurring growth may have been 

 aggravated in 1959 by irregular feeding. 



Another exception to the general rule that 

 fish gained weight when fed and lost weight 

 when starved was an unexpected gain by the 

 starved fish between August 28 and September 

 11, 1959. Because the condition factor, unlike 

 mean length and weight of that lot, decreased 

 during that period, it appears that a sampling 

 error was involved, i.e., that the sample 

 somehow contained fish that were longer and 

 heavier but not more robust than those in the 

 previous sample. Evidence indicates that a 

 similar type of sampling error occurred in the 



