RESULTS 



The survey is incomplete insofar as 

 samples were not obtained from all species 

 normally found at the various hatcheries. For 

 the purpose of this work only chinook salmon, 

 Oncorhynchus tshawytscha and silver salmon, 

 Oncorhynchus kisutch were considered since 

 these two species are the only ones normally 

 reared for any appreciable length of time at the 

 hatcheries examined. At the Elokomin, Toutle 

 and Lewis River hatcheries, samples of both fall 

 chinook and silver salmon were obtained. At the 

 Kalama, Klickitat and Samish hatcheries only 

 fall chinook salmon samples were collected. 

 Klickitat hatchery also receives a run of spring 

 chinook salmon in addition to the fall chinook and 

 silver salmon runs but no spring chinook salmon 

 samples were obtained. No samples were col- 

 lected from fish spawning naturally in this area 

 which could be considered of "wild" stock as op- 

 posed to those reared artificially in hatcheries. 

 Insufficient length-weight data were collected to 

 be of significance . 



The results of the survey for acid-fast 

 bacteria are presented in table 1 by hatcheries 

 and species. Results obtained by the direct 

 smear and by the concentration method are 

 listed separately. 



DISCUSSION 



Tuberculosis in salmon was first reported 

 in adult chinook salmon returning to the Bonne- 

 ville hatchery on the Columbia River by Earp, 

 Ellis and Ordal (1953). It has since been postu- 

 lated that the incidence of this disease in adult 

 salmon might be connected, in some manner, to 

 hatchery techniques, particularly the practice 

 of feeding fresh frozen salmon products in the 

 form of viscera and spawned out carcasses to 

 young salmon as part of the hatchery diet . The 

 feeding of salmon carcasses has been discontin- 

 ued in the Columbia River Basin hatcheries by 

 the State of Washington Department of Fisheries 

 but frozen salmon viscera is still a major part 

 of the hatchery diet . 



Under normal hatchery procedures, fall 

 chinook salmon are artificially reared for approx- 

 imately 90 days from the time the fish start 

 feeding and are then released to the stream for 

 migration to the sea . Spring chinook salmon 



and silver salmon are reared for periods up to 

 12 months before being released in accordance 

 with their normal migration pattern. Chum sal- 

 mon ( Oncorhynchus keta) and pink salmon 

 ( Oncorhynchus gorbuscha ) migrate almost im- 

 mediately to the sea after emerging from the 

 gravel and are seldom reared artificially for any 

 extended period in fresh water hatcheries. Only 

 occasional small experimental lots of blueback 

 salmon ( Oncorhynchus nerka) are reared in Col- 

 umbia River hatcheries by the State of Washington 

 Department of Fisheries . Therefore, under nor- 

 mal hatchery conditions, chum and pink salmon 

 are seldom artificially fed at these hatcheries, fall 

 chinook are fed for approximately 90 days and 

 spring chinook and silver salmon may be fed for 

 periods of up to one year . 



Considering the hypotheses that infection 

 by acid-fast bacteria in salmon is introduced by 

 the feeding of infected salmon products and that 

 the incidence of infection is directly proportional 

 to the length of time salmon are artificially reared 

 (and exposed to infected foodstuffs), it could be ex- 

 pected that silver salmon and spring chinook salmon 

 would show a higher incidence of infection than 

 would fall chinook salmon. The results obtained 

 in the survey at Elokomin and Lewis River hatch- 

 eries tend to bear out this hypothesis , particularly 

 so in the case of Lewis River hatchery where in- 

 cidence in the silver salmon was relatively high 

 while the chinook salmon showed no incidence of 

 the disease. At the Toutle hatchery, however, 

 more chinook salmon than silver salmon were in- 

 fected. Unfortunately the data are incomplete 

 inasmuch as we have no samples from silver sal- 

 mon at three of the hatcheries to compare with the 

 incidence of infection in the chinook salmon. 



Another incongruity was found in the case 

 of the samples taken at the Elokomin hatchery 

 which included both chinook and silver salmon. In 

 both species taken at this hatchery a larger per- 

 centage of positive smears was detected by the 

 direct smear method than was found by the con- 

 centration method. In all cases the acid-fast 

 bacteria in the Elokomin samples proved to be 

 severely damaged by the technique of concentration, 

 retaining little if any of the typical morphology of 

 acid-fast bacteria from samples taken at the other 

 hatcheries. It is postulated that the bacterium 

 found in the Elokomin fish differs in some respect 

 from those found in fish from other locations and 

 may represent an entirely different organism . 



11 



