2. A 2-week interval commencing no later 

 than mid-July appears to be the optimum 

 duration and time for marking success. Tim- 

 ing appears to be important because it allows 

 time for a summer rather than a fall-recovery 

 period. Fish whose recovery period extends 

 into the fall do not mark well. 



3. The scale mark does not show in appre- 

 ciable numbers until the fish have resumed 

 feeding for 2 to 4 weeks. 



4. Starved fish readily resume feeding and 

 growing when food is reintroduced. Although 

 they do not make up for lost growth (observa- 

 tion time limited to 10 weeks after starva- 

 tion), they regain their robustness and outward 

 vigor. 



determine if the scales of hatchery-reared 

 fish could be identifiably marked by short 

 periods of starvation. Fish were starved 2, 

 4, 6, and 8 weeks and returned to food. Lots 

 were sampled every 2 weeks for length, weight, 

 and scales. In 1959 marking success in the 2- 

 week test lots ranged between 87 and 94 per- 

 cent after the fish had been returned to food 

 for 4 weeks. Excellent marking success was 

 also obtained in the 4-week lot but not until 

 the fish had resumed feeding for at least 6 

 weeks. Few marks were noted in the 6- or 

 8-week lots. In 1960, satisfactory marking 

 success was obtained in only the first of 

 the three 2-week lots. The 4-week lot marked 

 well but, as in 1959, not until after 6 weeks 

 of resumed feeding. In either year, control 

 fish seldom were marked. 



From the experim_ental results have emerged 

 the following questions: 



Could marking success be obtained with a 

 starvation interval of less than 2 weeks? Might 

 not the intensity of the mark be made more 

 distinct by surrounding it with areas of arti- 

 ficially accelerated growth? Could marking 

 success be obtained by starving the fish 

 earlier in their life? Do starved fish ever 

 make up for lost growth? What is the long- 

 range effect of starvation on survival? What 

 is the mark recognition to the migrant stage? 

 To the adult stage? Do wild fish sometimes 

 lay down a false check that might be confused 

 with the starvation mark? Or, will the starva- 

 tion mark be confused with a true annulus? 

 Large-scale experimentation to answer some 

 of these and other questions associated with 

 the development of a starvation-marking tech- 

 nique is being continued at Leavenworth in 

 1961. 



SUMMARY 



3. Mortalities (1 in 1959 and 52 in 1960) 

 were confined to the starvation lots. Mortality 

 did not become a factor in 1960 until the fifth 

 and sixth weeks of starvation. 



4. Fish generally lost weight during starva- 

 tion but resumed feeding and growing when 

 returned to food. Although most lots of starved 

 fish rapidly regained their robustness (condi- 

 tion factor often met or exceeded that of 

 control fish), they did not make up for lost 

 weight. Fish starved 2 weeks lagged behind 

 control fish by 22 to 33 percent at the end of 

 the experiment. Growth generally leveled off 

 after September 1. 



5. We are unable to pinpoint the exact 

 reason that some 2-week lots marked and 

 others did not. Indications are that timing is 

 important, e.g., starvation should be con- 

 ducted in early July, thus allowing fish to 

 recover during the summer rather than dur- 

 ing the fall months when growth naturally 

 slows. 



1 . Wild and hatchery-reared sockeye salmon 

 of the same parent stock are mixed in the 

 seaward migrations from Lake Wenatchee. 

 An economical means is needed for separating 

 the components, thus allowing evaluation of 

 the wild and hatchery production. 



2. Experiments were conducted at the 

 Leavenworth hatchery in 1959 and 1960 to 



6, On the basis of these experiments we 

 conclude that under certain conditions a highly 

 identifiable mark can be imprinted on the 

 scales of hatchery-reared sockeye with little 

 mortality. Weight loss due to starvation may . 

 be offset at least in part by the .fact that the 

 fish, although smaller, have a condition factor 

 comparable to or higher than that of the 

 control fish. 



11 



