and were capable of distinguishing 100 discrete 

 crystal-tuned transmitters. Sturgeon, including 

 those radio-tagged in 1975 and 1976 (Haynes et al. 

 1978), were located once or twice per week with 

 boat- and truck-mounted receiver gear. On several 

 occasions, sturgeon locations were monitored 

 manually over a 24-h period. 



During the summer we measured Columbia 

 River temperatures at numerous midchannel lo- 

 cations from Priest Rapids Dam to Richland, 95 

 km downstream (Figure 1). On these occasions 

 river temperatures only varied about 1° C. There- 

 fore, mean river temperatures (standard deviation 

 = 0.5° C/d) during the study were calculated from 

 12 temperature readings taken daily at Priest 

 Rapids Dam. Daily mean river temperatures were 

 averaged weekly Main current temperatures in 

 White Bluffs Pool were monitored by a reference 

 temperature transmitter in the pool and were also 

 measured while tracking fish. 



Analysis of variance was used to compare mean 

 sturgeon environmental temperatures in six 

 time periods (0200-0600, 0600-1000, 1000-1400, 

 1400-1800, 1800-2200, and 2200-0200 h) with the 

 weekly mean river temperature from 19 June to 20 

 August 1977. Differences between sturgeon en- 

 vironmental temperatures and weekly average 

 river temperatures were experimental units 

 within each time period. Honest significant differ- 

 ence (HSD) tests (Snedecor and Cochran 1972) 

 were used to establish which periods differed. 



White Bluffs Pool is 1.5 km long and has three 

 distinct habitats (Figure 1). Most of the pool is part 

 of the deep, swiftly flowing main current of the 

 Columbia River and has a rock bottom. A deep, 

 slow-moving back eddy with a sandy bottom lies 

 off the tip of White Bluffs Peninsula. White Bluffs 

 Slough has a mud and rock bottom and extends 1 

 km upstream along the peninsula. The pool ranges 

 in depth from 1 m in the slough to 20 m in midpool, 

 and the main current is well mixed (Gray et al.^; 

 Page et al."*). However, underground spring seep- 

 age areas, common in the region, are l°-5° C lower, 

 and slough areas are 2°-5° C higher, than mixed 

 main currents in summer (Haynes 1978). 



•'Gray, R. H., T. L, Pase, and E. G. Wolf. 1976. [Report on 

 aquatic ecological studie.s near WNP-1, 2, 4, Sept. 1974-Sept. 

 1975. WPPSS Columbia River ecology studies, Vol 2 115 

 p.^ Battelle,Pac. Northwest Lab., Richland Wash 



,aZ''^%'^- h- ^- "• ^""^y- ^- ^- W"'^- ='"^ M. J. Schneider, 

 u u ""^P"*"^ °" aquatic ecological studies conducted at 



the Hanford Generating Project 1973-74. WPPSS Columbia 

 River ecology .studies, Vol. 1, 206 p. Battelle, Pac. Northwest 

 Lab., Richland, Wash. 



368 



Results and Discussion 



Main current temperatures in White Bluffs Pool 

 averaged within 0.5° C of Priest Rapids Dam 

 temperatures and weekly standard deviations av- 

 eraged 0.3° C throughout 1977. Therefore, devia- 

 tions in daily and weekly midriver temperatures 

 were small relative to temperature differences in 

 spring seepage and slough areas in summer. 

 Throughout the summer of 1977, individual stur- 

 geon with temperature transmitters engaged in 

 movements that often resulted in a 2°-4° C daily 

 change in recorded temperature. The analysis of 

 sturgeon environmental temperatures versus 

 weekly average river temperatures during certain 

 periods of the day (Table 1) indicated significant 

 differences (P<0.001). Because deviations in main 

 river temperatures were 8-25'7f less within and 

 between days than changes in sturgeon environ- 

 mental temperatures, recorded temperature 

 changes indicated sturgeon moved into areas of 

 differing environmental temperatures. Position 

 determinations confirmed these movements and 

 indicated sturgeon generally occupied mid- 

 channel areas from early morning until midafter- 

 noon. Movements into nearshore and slough areas 

 were observed in late afternoon and evening. 



During summer 1977 from 0200 to 1000 h, stur- 

 geon environmental temperatures ( Figure 2 ) were 

 somewhat, but not significantly, lower ( -0.35° C) 

 than weekly average river temperatures, suggest- 

 ing presence in deeper, and possibly spring-fed 

 areas. During 1400-2200 h, sturgeon environmen- 

 tal temperatures were significantly (P<0.05 by 

 HSD) higher (0.85° C) than the weekly average 

 river temperature, indicating presence in warmer, 

 shallow slough areas. During 1000-1400 h and 

 2200-0200 h, sturgeon environmental tempera- 

 tures were somewhat higher (0.32° C) than the 

 weekly average, suggesting transition periods 

 when sturgeon moved between inshore and mid- 

 channel areas. 



Although changes in sturgeon environmental 

 temperatures documented movements among 



Table l.— Analysis of variance on differences in mean sturgeon 

 environmental temperatures in six daily time periods (0200- 

 0600, 0600-1000. 1000-1400, 1400-1800, 1800-2200, and 2200- 

 0200 h). 



Source 



df 



SS 



MS 



Among time periods (diel) 

 Within time periods 

 Total 



5 

 701 



706 



164.67 32.93 

 485.28 069 



649.95 



47.7-- 



*p<a.ooi. 



