the ocean are^ In a sense, dovnstreaB 

 migrants. Only Juvenile downstream migrants 

 are considered in this report. 



Although the percentages of night 

 migrants in 1952 and I953 differed, the 

 hourly catches reached their maxima at the 

 same hours. 



HOURLY MOVafflHT 



The hourly catches of all species are 

 listed in table 1 for 1952 and In table 2 

 for 1953. The catches in table 1 represent 

 four periods (April 9-11, April 22-25, 

 April 28 - May 1, and May 5-7) totalling 

 2I4O hours of sampling; the catches in 

 table 2 represent four periods (March IO-I3, 

 April 20-23, April 28 - May 1, and May '^-7) 

 totalling 288 hours of sampling. These 

 periods were selected because migrants were 

 most abundant on those dates. Hourly 

 sampling was limited to two traps (one in 

 the powerhouse channel and the other in the 

 spillway channel) because only one observer 

 was available for each 8-hour shift. 



Chinook Fingerlings 



Chinook fingerlings in both 1952 and 

 1953 were caught in greatest numbers during 

 early morning and early evening hours 

 (figure 3). In both years the pesik morning 

 hour was 6 to 7 a.m. and the peak evening 

 hour, 7 to 8 p.m. The catch drops off 

 rather sharply on both sides of these hours. 



12 2 4 6 8 10 12 2 4 6 8 10 12 



AM HOUR PM 



Figure 3" — Hourly catches of cfainook fin- 

 gerlings in 1952 and 1953- Each 

 hour represents the summation of 

 the year's catch for that hour. 



Four 72-hour periods were plotted for 

 1953 (figu« k). From March 10 to March 13 



30 

 28 



26 



24 



22 



20 



18 



16 



14 



12 



10 



8 



6 



4 



2 



12 2 4 6 8 10 12 2 4 6 8 10 12 

 AM PM 



HOUR 



MARCH 10-13 I 273 FISH 



APRIL 20-23 275 FISH 



APRIL 28-MAYl 2380 FISH 



MAY 4- 7 179 FISH 



FlguTs k. 



-Parcent of Chinook f logarlin^s cau^t each hour 

 during four 72-bour periods In 1933- 



sunrise was about 6:15 a.m. and sunset about 

 6:15 p.m. The catch peaked at 7 a.m. and 



7 p.m., which coincides with the hours of 

 dawn and dusk. The three periods from April 

 20 to May 7 bad smaTI morning peaiks, all 

 earlier than 7 a-m. A wellnnarked peedc 

 occurred in all three periods at 8 p.m. 

 S\mrise during these periods was between 

 k:iO and 5 a.m., and sunset between 7 bjoA 



8 p.m. There were too few fish in seme of 



