computed in order to determine if a relation- 

 ship existed between infection and length of 

 fish. 



RESULTS 



Natural spawning areas 



Livers were examined from chinook sal- 

 mon spawning under natural conditions in each 

 of 17 rivers in Washington. No incidence of 

 infection was found (table 1). 



Results obtained from the examination 

 of sockeye salmon spawning in the Okanagon 

 River are shown in table 2 . Although salmon 

 found in the Okanagon River are presumed to be 

 wild stocks, the possibility of strays from 

 hatchery stocks entering the river must be giv- 

 en consideration. 



Artificial spawning areas 



Little White Salmon Station 



Livers from fall chinook salmon were 

 collected and divided into three groups: random 

 sample, marked fish and grossly diseased or 

 abnormal fish . The random sample was sub- 

 divided by sex and the results of the examination 

 are shown in tables 3 and 4. X 2 values indicated 

 the infection was randomly distributed in the 

 female population with respect to length class, 

 however, the proportion of infected fish in each 

 size stratum was not equal in the males . A X 2 

 value of 14.98 was calculated from the data 

 which is significant at the .01 level with 2 de- 

 grees of freedom. It is possible this group was 

 composed of two age -classes with the higher 

 incidence of infection occurring in the older 

 fish. 



Carson Station 



Livers were collected from 387 spring 

 chinook salmon trapped at Bonneville Dam and 

 held at the Carson station (tables 5, 6 and 7). 

 In contrast to the results obtained at the Little 

 White Salmon station the female upstream mi- 

 grants held at this hatchery appeared to be 

 composed of two age -classes; however, the 

 larger fish again showed a higher incidence of 

 infection with a calculated X 2 value of 14.72 

 being significant at the .01 level with 3 degrees 

 of freedom. Infections appeared to be random- 

 ly distributed between length -classes in the 

 male population. 



Entiat Station 



Summer chinook and sockeye salmon 

 were taken at the Entiat hatchery. Due to the 

 relatively small number of fish available of 

 each species, no attempt was made to compare 

 the samples by sex. The X value was computed 

 for each species only, and the incidence of in- 

 fection was determined to be proportionate to 

 the length class for both groups (tables 8 and 9). 



In a number of instances either no in- 

 fection was present, or complete data was 

 unavailable. Percent infection rates are tabu- 

 lated for this group in table 10 . 



DISCUSSION 



Due to the varied procedures and avail- 

 ability of personnel at different stations, there 

 is some variation in the resulting data. In- 

 formation regarding lengths and sex was not 

 available for all fish from which livers were ob- 

 tained; therefore, direct comparisons cannot 

 be made at all hatcheries. 



Sixty-three livers were obtained from 

 grossly abnormal fish. Fish were considered 

 to deviate from the normal if lesions were 

 present on the liver, kidney or spleen. In ad- 

 dition, fish showing off coloration, retardation 

 of growth and/or underdeveloped gonads were 

 also considered abnormal. Acid-fast bacilli 

 were present in 100 percent of this sample. 

 Thirty-eight fish marked with fin clips returned 

 to the hatchery with 22 being infected (table 5). 



Analysis of length versus incidence of 

 infection revealed significant differences in two 

 of six samples. The two groups consisted of 

 male fall chinook salmon from the Little White 

 Salmon station and female spring chinook from 

 the Carson station. In both instances, however, 

 length -frequency curves indicated the possible 

 presence of 2 year-classes in the sample. A 



