as shallows at stream edges or in close proximity 

 to physical objects. Recently emerged steelhead 

 trout fry, observed adjacent to my study area in 

 the Cedar River in 1965-66, were rarely found 

 along sandy shore areas but were commonly seen 

 among rocks at depths of 1 to 5 cm -when dis- 

 turbed they hid under the rocks. The use of ex- 

 treme shallows by steelhead trout fry may in part 

 be an innate response to predators since this type 

 of habitat in streams is relatively barren of other 

 fish. 



Literature Cited 



Hartman, G.F. 



1965. The role of behavior in the ecology and interaction of 

 underyearling coho salmon (Oncorhynchus kisufch) and 

 steelhead trout {Salmo gairdneri). J. Fish. Res. Board 

 Can. 22:1035-1081. 



Hunter, J. G. 



1959. Survival and production of pink and chum salmon in a 

 coastal stream. J. Fish. Res. Board Can. 16:835-886. 

 Mason, J. C. 



1974. Behavioral ecology of chum salmon fry (Oncorhynchus 

 kefa) in a small estuary. J. Fish. Res. Board Can. 

 31:8:3-92. 

 Patten, B. G. 



1962. Cottid predation upon salmon fry in a Washington 

 stream. Trans. Am. Fish. Soc. 91:427-429. 



1971a. Predation by sculpins on fall chinook salmon, On- 

 corhynchus ffshawytscha. fry of hatchery origin. U.S. 

 Dep. Commer., Natl. Mar. Fish. Serv., Spec. Sci. Rep. 

 Fish. 621, 14 p. 



1971b. Increased predation by the torrent sculpin, Cottus 

 rhotheus. on coho salmon fry, Oncorhynchus kisufch, 

 during moonlight nights. J. Fish. Res. Board Can. 

 28:1352-1354. 



1972. Predation, particularly by sculpins, on salmon fry in 

 fresh waters of Washington. U.S. Dep. Commer., NOAA, 

 Natl. Mar. Fish. Serv., Data Rep. 71, 21 p. on 1 microfiche. 



RiCKER, W. E. 



1941. The consumption of young sockeye salmon by 

 predaceous fi.sh. J. Fish. Res. Board Can. 5:293-313. 

 Shelboukn, .1. E. 



1966. Influence of temperature, salinity, and photoperiod on 

 the aggregations of chum salmon fry (Oncorhynchus 

 keta). i. Fish. Res. Board Can. 23:293-304. 



Sheridan, W. L., and W. R. Meehan. 



1962. Rehabilitation of Big Kitoi outlet stream, Afognak 

 Island, .-Maska. Alaska Dep. Fish Game, Div. Biol. Res. 

 Inf.Leafl.il. 13 p. 



Benjamin G. Patten 



Northtveat Fisheries Center 



National Marine Fisheries Service, NOAA 



2725 Montlake Boulevard East 



Seattle, WA 9S112 



HERITABLE RESISTANCE TO GAS BUBBLE 



DISEASE IN FALL CHINOOK SALMON, 



OSCORHYSCHUS TSHA W'YTSCHA' 



Construction of a series of dams on the Columbia 

 River has resulted in air-supersaturation of the 

 river during spring and early summer. Air-super- 

 saturation is caused by the entrainment of air in 

 water at depths as great as about 15 m in the 

 plunge basins of the spillways below each dam. 

 The level of air-supersaturation varies according 

 to the amount of water-flow over the spillways 

 (Ebel 1969). Supersaturation levels which are 

 known to be fatal to salmonid fishes (Rucker and 

 Hodgeboom 1953; Westgard 1964; Ebel 1969; and 

 Blahm et al. 1975) are often sustained in the 

 Columbia River from April through July, the 

 period when many juvenile salmonids emigrate to 

 the ocean. 



Salmonids vary greatly in their tolerance for 

 supersaturation (Ebel 1969). If a portion of this 

 variability is related to additive genetic factors, an 

 increase in the average tolerance of salmon 

 populations to air-supersaturation can be expected 

 as a result of selection. The purpose of this study 

 was to estimate the influence of genetic factors on 

 resistance to gas bubble disease for fall chinook 

 salmon, Oncorhynchus tshawytscha. Specifically, 

 the objectives were: 1) To determine the heri- 

 tability of resistance to death from gas bubble 

 disease for a stock of Columbia River fall chinook 

 salmon, and 2) to determine the inherent level of 

 resistance to gas bubble disease for several fall 

 chinook salmon stocks. 



Methods 

 Estimation of Heritability 



Juvenile fall chinook salmon representing 80 

 families were reared at the Abernathy Salmon 

 Cultural Development Center, near Longview, 

 Wash. The families were produced by mating 20 

 males to 80 females, 4 females per male, in a nest- 

 ed breeding experiment. One hundred fish from 

 each family were marked by cold-branding 

 (Everest and Edmundson 1967) when they were 4 

 mo old and their weights averaged 2 g. Each group 

 of 100 fish received a unique mark. 



'This work was carried out in cooperation with the U.S. Fish 

 and Wildlife Ser\'ice, Oregon Fish Commission, Oregon Wildlife 

 Commission, and Oregon State University. 



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