10- 



S: 5 



o 100 

 z 80 



6-weeK starvotion tol 



4-week storvotion lol 



2-week siorvation tot 

 (B) 



2-week storvotion lot 

 (A) 



0.8 o 

 06 P 



7-21 8-3 8-18 9-2 

 SAIVIPLING DATE 



Figure 6. --Growth rates of the various lots in the 1960 

 experiment to mark the scales of sockeye salmon 

 fingerlings by short periods of starvation. 



duration. Although growth was noted in all 

 test lots following reintroduction of food, in 

 no case within the experimental confines did 

 the mean weight of the test fish exceed that 

 of control fish. The amount by which the mean 

 weight of the various test lots lagged behind 

 that of the control fish corresponds directly 

 to the duration of the starvation period. It is 

 noteworthy that at the end of the experiment, 

 the condition factor of the control fish was 

 roughly the same as that of the 2-week test 

 lot and was even exceeded by that of the 

 4-week test lot. 



Remarkable agreement exists between the 

 main growth features of the 1959 and 1960 

 tests, despite differences in diet, duration of 



the experiment, and initial size of the test 

 fish. We have already shown that growth gen- 

 erally slowed after mid-September in both 

 years. The ability of starved fish to resume 

 feeding and growing was also observed in 

 both years as was the final weight lag between 

 the control and test lots. As was the case in 

 1959, the condition factor of some of the final 

 1960 test lot samples nearly equaled that of 

 the control sample. Despite the variations 

 in timing of the starvation period, the three 

 1960 2-week lots exhibited similar mean 

 weights at the end of the experiment (8.44, 

 8,15, and 8.10 grams for the first, second, 

 and third variations, respectively). 



DISCUSSION 



In our presentation of the experimental 

 results we have placed particular emphasis 

 on the variability between the various test 

 lots with respect to such salient features as 

 marking success, weight loss during starva- 

 tion, and the final mean weight and condition 

 factor. When the above items are considered 

 together it is obvious that, of the intervals 

 tested, the optimum duration of starvation is 

 the shortest (2-week) period. 



Widely divergent marking success was ob- 

 tained in the three 1960 2- week test lots even 

 though the lots finished the experiment with 

 approximately the same mean weight. Further 

 examination reveals that for these lots, mark- 

 ing success is inversely related to the tim- 

 ing of the starvation and recovery period, 

 i.e., the first 2-week lots were marked the 

 best, the second period the second best, etc. 

 If, as we assume, starvation was the same 

 in all cases, it is apparent that some other 

 factor(s) associated with the time variable 

 influenced marking success. Among the time 

 (seasonal) associated factors of possible im- 

 portance in this experiment were (1) water 

 temperature, (2) size of the fish at the onset 

 of starvation, and (3) growth rate. Let us 

 examine the results of the three 2-week test 

 lots in terms of these factors. 



The mean daily water temperature during 

 the starvation (fig. 7) period was 59.5, 61.5, 

 and 59.7 degrees for the first, second, and 

 third 2-week test lots, respectively. The 



