BAILEY ET AL.: PRODUCTION OF FRY AND ADULTS AT AUKE CREEK 



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JKE CREEK 



INCUBATORS 



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 AUG. 



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5 15 25' 5 

 SEFT. 





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15 25 

 OCT. 



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5 15 25' 5 15 25 ' 5 15 25 ' 5 

 NOV. DEC. JAN. 





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 15 25' 5 15 25 ' 5 15 25' 5 15 25 



Figure 1. -Temperatures in 

 gravel incubators and in surface 

 water of Auke Creel<, 8 August 

 1972 through 17 May 1973. 



FEB. 



MARCH 



APRIL 



the procedure were of insufficient detail to es- 

 timate the precision of the initial seedings. Vari- 

 ances of these initial seedings were estimated 

 from data obtained in recent years, 1974 and 1975. 

 This source of error was determined to be negligi- 

 ble in later calculations. 



Eggs were fertilized on the following schedule: 

 incubator A, 4-31 August; B, 4 August to 8 Sep- 

 tember; C, 11-17 September; and D, 17-21 

 September. 



Water Temperatures 



We measured temperatures daily with a mer- 

 cury thermometer (to the nearest 0.1°C) in Auke 

 Creek and in the incubators from the time the first 

 eggs were collected until the fry left the creek. 

 While eggs were being collected (8 August to 22 

 September 1972), water in Auke Creek was 

 warmer than water in the incubators (Figure 1). 

 The creek water was cooler than the incubator 

 water from 9 October throughout the rest of the 

 incubation period, which ended when the fry 

 emerged. 



Oxygen Levels 



Oxygen concentrations in the water supply to 

 the hatchery and in effluents from the incubators 

 were measured to the nearest 0.01 mg/liter by the 

 Winkler method. Oxygen was measured at weekly 

 intervals from shortly after eyed eggs were seeded 

 (9 November 1972) until the fry began to emerge 

 (23 March 1973). Oxygen content of the water 

 supplied to the incubators decreased steadily- 

 from 9.6 mg/liter (73% saturation) on 22 

 November 1972 to 7.8 mg/liter (59% saturation) on 

 23 March 1973 (Figure 2). Oxygen in effluents from 

 gravel incubators decreased from 9.3 mg/liter 

 (71% saturation) to 6.7 mg/liter (51% saturation) 

 during the same period. 



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SOURCE WATER 



EFFLUENT WATER 



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NOV 



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DEC. I JAN 



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25 



FEB 



MAR 



Figure 2.-Dissolv'ed oxygen levels in source water and effluent 

 water of gravel incubators at Auke Creek Hatchery, 9 November 

 1972 through 23 March 1973. 



Counting and Processing Fry 



We collected emigrating creek fry and hatchery 

 fry to measure and mark, to determine time of 

 migration, and to estimate abundance of hatchery 

 fry. Two 0.91- by 0.91-m fyke nets with floating 

 live-boxes were used to index the daily emigration 

 of creek fry and to collect fry for a mark and 

 recovery experiment. The daily counting of fry as 

 they emerged from gravel incubators and the 

 collection of fry for fin clipping and measuring 

 was expedited by passing the incubator effluents 

 over a cone-shaped sampling device-^ and then 

 through a second sampling device consisting of a 

 set of five parallel troughs. The first device provid- 

 ed small subsamples of fry from which total 

 numbers emerging could be estimated; the second 



3A blueprint for the cone-shaped fish sampler was supplied by 

 the Washington Department of Fisheries. 



963 



