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



667/84,000 = 0.0079 (SE: 0.0003). Estimated sur- 

 vival of creek fry for the same period is 

 74/5,500 - 0.0135 (SE: 0.0016). Therefore, our 

 estimate of relative survival of hatchery fish as 

 compared to creek fish is 0.0079/0.0135 = 0.59 (SE: 

 0.071). 



although the precision of that estimate is ex- 

 tremely low, as indicated by the standard error-a 

 rough 95% confidence interval would include the 

 possibility that survival from potential egg depo- 

 sition to adult was smaller for hatchery operations 

 than for natural spawning. 



Table 2.-Source of recoveries ofmarked pink salmon adults 

 originating from fry marked at Auke Creek in 1973. 



Survival from Egg to Returning Adult 



While hatchery fry suffered greater losses than 

 creek fry in the marine environment, their in- 

 creased survival under the artificial conditions 

 during incubation was compensating. Overall 

 relative survival from potential egg deposition to 

 returning adult can be estimated as the ratio of 

 the products of survival from potential egg depo- 

 sition to alevin and from fry to returning adult for 

 hatchery and creek fry. The survival of hatchery 

 fish relative to creek fish is 



(0.743)(0.0079)/(0.079)(0.0135) = 5.50 (SE: 2.59). 



Production of adults by the hatchery is estimated 

 to be 5 to 6 times that of natural production, 



Survival from Marking Effects 



Estimates of the initial numbers of unmarked 

 creek and hatchery fry are 68,400 and 495,000, 

 respectively. Unmarked recoveries to the weir 

 totaled 5,545. Survival of marked fry to return at 

 the weir is estimated by the ratios of marked 

 recoveries at the weir (Table 2) to numbers of 

 marked fry released, or 71/5,500 = 0.01291 for 

 creek fry and 644/84,000 = 0.00767 for hatchery 

 fry. Then survival from marking is estimated to be 



[(68,400)(0.01291) + (495,000) 

 (0.00767)]/5,545 = 0.84. 



Determination of the precision of the marking 

 mortality estimate was not attempted because of 

 the apparent complexity of the problem. 



Fry Size and Developmental Index 



Most of the fry from gravel incubators were 

 shorter (Figure 4) but heavier (Figure 5) than 

 creek fry, although there were two exceptions: fry 

 from incubator A had an average weight of 260.0 

 mg, which was not significantly different from the 

 average weight for creek fry-260.2 mg (Table 3); 



CREEK 



INCUBATOR A 

 fNCU BATOR B 

 INCUBATOR D 

 INCUBATOR C 



31.1 31.5 31.6 31 7 31.8 



CREEK 



INCUBATOR A 

 INCUBATOR B 

 INCUBATOR C 

 INCUBATOR D 



24S 



31.9 32.0 32.1 32.2 

 LENGTH OF FRY (MM) 



32.3 32.1 32.5 32.6 32.7 



Figure 4. -Weighted means and 95% 

 confidence intervals for these means of 

 lengths of preserved fry from Auke Creek 

 and four gravel incubators. 



250 



260 265 



WEIGHT OF FRY (MG) 



270 



275 



Figure 5. -Weighted means and 95% 

 confidence intervals for these means of 

 weights of preserved fry from Auke 

 Creek and four gravel incubators. 



967 



