FISHERY BULLETIN: VOL. 74, NO. 4 



returning adult salmon. The hatchery water sup- 

 ply came from nearby Auke Lake. The eggs were 

 incubated to the eyed stage in Heath'^ incubators 

 and then transferred to gravel incubators to 

 complete development. 



Water Filter and Purifier 



The water filter and ultraviolet purifier system 

 supplied treated water to one-half of the hatchery 

 incubators; the rest were supplied with untreated 

 water. The filter was rated to remove particles 10 

 jtim in diameter or larger. The purifier was de- 

 signed to give a minimum dosage of 35,000 

 iiiW-s/cm^' at 2,537 A. The water treatment had no 

 apparent beneficial effect. 



Natural Spawning 



From 4 August to 21 September 1972, 1,768 

 adult pink salmon entered the fish counting weir. 

 About 55%, 459 females and 527 males, were 

 released to spawn above the weir. The rest were 

 kept for fecundity counts and hatchery spawn 

 source. Ten females from which we obtained 

 fecundity counts were treated as a simple random 

 sample in later analysis, although no serious effort 

 was made to assure randomness of selection. 

 Average fecundity in this sample was 2,035 

 eggs/female (SE: 93.27). This estimate agreed 

 closely with 2,023 eggs/ female from an inventory 

 of eggs obtained from the 386 females used as the 

 hatchery spawn source after a rough correction for 

 eggs retained. Most pink salmon released above 

 the weir spawned in a 297-m section of stream 

 between the weir and Auke Lake. Fewer than 20 

 adults spawned in Lake creek above Auke Lake. 

 The alevin population of Auke Creek was es- 

 timated 20-21 March 1973 with a hydraulic pump 

 census (McNeil 1964). 



Collection and Eyeing of Eggs 



Eggs for seeding incubators were obtained from 

 the Auke Creek pink salmon run 8 August through 

 22 September 1972. These dates cover nearly the 

 entire run, thereby assuring representation of all 

 parts of the run in the next generation. Eggs were 

 collected from 386 females (about 45% of the 

 females in the spawning run) in the manner 



described by Bailey and Taylor (1974). Malachite 

 green treatments, 15 ppm. for 1 h, were used at 

 weekly intervals between 17 August and 19 Oc- 

 tober to control fungus growth until eyed eggs 

 were removed from the Heath trays. 



Raising Eyed Eggs to Fry Stage 



The eyed eggs were raised to the fry stage in 

 four gravel incubators (Bams 1970) designated A, 

 B, C, D (Table 1). The incubators measured 1.2 by 

 1.2 by 1.2 m and used a system of perforated pipes 

 and horizontal layers of graded gravel to achieve 

 uniformity of upwelling flow through the eggs and 

 gravel. Flow to A, B, and C was initially set at 75 

 liters/min and to D at 79 liters/min. Incubators A, 

 B, and C were loaded with an estimated 150,000 

 eggs (SE: 1,030) each and incubator D with an 

 estimated 158,000 eggs (SE: 1,085) (Table 1). 

 Therefore each incubator initially contained 2,000 

 eggs per liter/min. 



Iron bacteria sheaths and a flocculent iron 

 precipitate accumulated in the incubators. The 

 material seemed to accumulate as rapidly in 

 incubators receiving filtered and irradiated water 

 as in those receiving untreated water. The in- 

 tended water flow through the incubators receiv- 

 ing treated water could not be maintained. Flow 

 through incubator C had dropped from the desired 

 1.26 liters/s to 0.88 liter/s 18 December 1972, and 

 flow through incubator B had dropped to 0.95 

 liter/s 3 January 1973. Flow through these in- 

 cubators was maintained at 0.63-1.07 liters/s for 

 the rest of the incubation period. The full 1.26 

 liters/s was maintained at all times in the two 

 incubators receiving untreated water, probably 

 because the hydraulic head on the untreated water 

 supply was about twice the head on the treated 

 water. 



The estimates of numbers of eggs seeded in each 

 incubator were determined by the method of 

 Burrows (1951). Through an oversight, records of 



Table L-Operating conditions in four gravel incubators seeded 

 with eyed pink salmon eggs, Auke Creek, 1972. For each 

 incubator the volume of substrate and eggs was 1.246 m-'. 



-Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



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