with continuous aeration. Respirometers were closed at the end of tKe 

 third hour and ojcygen concentrations were monitored for 1 hour. Flow 

 rates were gradually increased to 1.58 ft/s. 



Base-line oxygen consumption rates of a 50- and a 15Q-gram fish swim- 

 ming at 1.05 ft/s were 23.2 and 55.0 mg O2 h"^, respectively. At a swim- 

 ming speed of 1.58 ft/s, a 50-gram fish consumed 23.2 mg O2 h"-^ ; a 150- 

 gram fish consumed 48.1 mg O2 h"-^. Respiration rates at the two swimming 

 speeds were, not significantly different, and sex influence on oxygen 

 consumption rates was not apparent at either speed (Table 14). 



Respiration rates of striped bass swimming at 1.05 and 1.58 ft/s 

 during exposure to 1.31 and 1.33 g 1"-^ natural sediment, respectively, 

 were reduced by 30 to 40 percent of the base-line values. At a swimming 

 speed of 1.05 ft/s, a 50-gram fish used 14.2 mg O2 h"^; a 150-gram fish 

 used 34.4 mg O2 h"-"- (Fig. 10; Table 15). Similar weight fish swimming at 

 1.58 ft/s consumed 14.1 and 34.9 mg O2 h"^ (Fig. 11; Table 15). Respira- 

 tion rates at the two swimming speeds were not significantly different, 

 and oxygen consumption rates of males and females during exposure to nat- 

 ural sediment were not different at either swimming speed (Table 14) . 



b. White Perch. Fish were maintained at about 15° Celsius and 5 

 parts per thousand salinity for a minimum of 3 days. Oxygen consumption 

 rates were determined at swimming speeds of 0.28 and 1.02 ft/s under 

 base-line conditions. At a swimming speed of 0.28 ft/s, a 50-gram fish 

 used 13.3 mg O2 h"^; a 150-gram fish used 27.1 mg O2 h"^. Fish of the 

 same weights swimming at 1.02 ft/s consumed 24.4 and 44.6 mg O2 h"-^, respec- 

 tively. Respiration rates were greater at swimming speeds of 1.02 ft/s 

 than 0.28 ft/s (Table 16); male and female respiration rates did not differ 

 at either speed (Table 16). 



Oxygen consumption rates were determined for white perch during exposure 

 to 1.09 g 1"-^ fuller's earth suspension at swimming speeds of 0.28 (Fig. 

 12) and 1.02 (Fig. 13) ft/s. The data were dispersed at both swimming 

 speeds--correlation coefficient, r = 0.017 (not significant) at 0.28 ft/s 

 and r = 0.201 (not significant) at 1.02 ft/s. Covariance analyses were 

 not attempted because of poor data correlation. 



Similar results were observed when oxygen consumption was determined 

 for white perch swimming at 0.39 and 1.05 ft/s during exposure to 2.12 

 g l"-*^ natural sediment suspensions. Low correlation coefficients, 

 r = 0.143 (not significant) at 0.39 ft/s and r = 0.017 (not significant) 

 at 1.02 ft/s, prevented further statistical treatment of these data. 



White perch were held in suspensions of 2.58 g 1" natural sediment 

 for 72 hours. Oxygen consumption rates were measured in filtered river 

 water at swimming speeds of 0.39 and 1.05 ft/s. Data for fish swimming at 

 0.39 ft/s after a 72-hour exposure were too scattered, r = 0.508 (not 

 significant), to permit further analysis (Fig. 14). After a 72-hour expo- 

 sure to natural sediment the oxygen consumption rates of a 50- and a 



39 



