PRODUCTION OF FRY AND ADULTS OF THE 1972 BROOD OF 



PINK SALMON, ONCORHYNCHUS GORBUSCHA, FROM GRAVEL 



INCUBATORS AND NATURAL SPAWNING AT AUKE CREEK, ALASKA 



Jack E. Bailey, Jerome J. Pella, and Sidney G. Taylor* 



ABSTRACT 



Production of fry and adults of the 1972 brood of pink salmon, Oncorhynchus gorbuscka, at Auke Creek, 

 Alaska, was compared between a grave! incubator hatchery and natural spawning. Natural production 

 in the creek above the hatchery weir (estimated from hydraulic sampling) was 73,900 fry (SE: 32,800) 

 from an estimated initial seeding of 934,065 eggs (SE: 42,81 1) for a survival rate of 0.079 (SE: 0.035). An 

 estimated total of 579,000 unfed fry (SE: 25,296) were released from the hatchery for a comparable 

 survival rate of 0.743 (SE: 0.047). Exactly 84,000 of the hatchery fry and 5,500 of the creek fry were 

 released after being marked by clipping fins. All adults returning to the weir were examined for marks, 

 and some additional marks were recovered from sport and commercial fishermen; 667 marked hatchery 

 fish and 74 marked creek fish were recovered. Estimated survival of hatchery fry to returning adult was 

 only 0.0079 (SE: 0.0003) equal to 0.59 (SE: 0.071) the corresponding estimate of 0.0135 (SE: 0.0016) for 

 creek fry, which suggests that hatchery fry were inferior to creek fry in the marine environment; 

 however, hatchery fry emigrated seaward 2 wk earlier than creek fry and may have encountered less 

 favorable marine conditions. Survival from eggs to returning adult stage was 5.50 times (SE: 2.59) 

 higher for hatchery fry than for creek frj' because of much greater survival from egg to fry in the 

 hatchery; the difference is not statistically significant. Hatchery fry were generally shorter but heavier 

 than creek fry and emigrated seaward at a slightly earlier stage of development. No differences in size 

 or time of return of adults could be traced to the incubation environment from which they came. 



The level of harvest of pink salmon, Oncorhynchus 

 gorbuscha, in Alaska in the 1970's (Seibel and 

 Meacham 1975) has been about one-ninth the level 

 of the 1930's (Kasahara 1963). This decline, in view 

 of recent advances in salmon hatchery systems 

 (Bams 1972), might be countered by large-scale 

 artificial propagation of salmon fry to supplement 

 natural spawning. As a first step toward develop- 

 ing systems for enhancing or rehabilitating the 

 depleted stocks, the National Marine Fisheries 

 Service, Northwest Fisheries Center Auke Bay 

 Fisheries Laboratory and the Alaska Department 

 of Fish and Game agreed in August 1971 to begin 

 testing a gravel incubator hatchery on Auke Creek 

 near Juneau in southeastern Alaska. 



Auke Creek was selected because it is accessible 

 and has a fish weir and a dependable water supply 

 from nearby Auke Lake. Lake water is especially 

 desirable for hatcheries in Alaska because the 

 water temperature generally remains above 

 freezing (3°-4°C). However, lake water has at least 

 one disadvantage-it has a different seasonal 



'Northwest Fisheries Center Auke Bay Fisheries Laboratory, 

 National Marine Fisheries Service, NOAA, P.O. Box 155, Auke 

 Bay, AK 99821. 



Manuscript accepted May 1976. 



FISHERY BULLETIN: VOL. 74, NO. 4, 1976. 



temperature pattern than most of the streambed 

 waters where pink salmon eggs normally incubate. 

 Bams (1972) avoided the problem of temperature 

 differences by collecting hatchery water from 

 beneath the streambed, but this is not always 

 feasible in Alaska because of the severe freezing 

 conditions encountered at many potential hatch- 

 ery sites. This report on the 1972 brood pink 

 salmon at Auke Creek compares hatchery produc- 

 tion and natural production in regard to 1) survival 

 from eggs to emergent fry, fry to returning 

 adults, and eggs to returning adults; 2) size, stage 

 of development, and emergence timing of fry; and 

 3) size and time of return of adults returning to 

 Auke Creek from hatchery and creek fry. 



MATERIALS AND METHODS 



A heated building (7.3 by 13.4 m) provided space 

 for a water filter and ultraviolet purifier; incuba- 

 tors; instruments for measuring temperature and 

 oxygen; equipment for censusing, sampling, and 

 marking fry; and instruments for measuring and 

 counting adult salmon. The building was located 

 on Auke Creek near a fish-counting weir at the 

 head of tide where eggs could be collected from 



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