( Salmo salar L.) in the River Spey as determined by

I sunrise Sunsn1
Figure 8.
The time of day when fish were actlve. Movements up stream and
down stream and from all phases of flsh mlgratlon are included. The
range of sunrise and sunset times for each sample period are shown.
From the data presented in Table V it is evident that there is a close
association between daylight migrations and increases in river discharge: of
the 30 daylight movements, 27 (90%) occurred during spate conditions
whilst only three (10%) took place when there was no spate.
Behaviour during the
ascent phase
Figure 9 shows the mean time of ascent for each monthly group of fish
to reach the Brae Water Beat No 5 ALSTN (9.2 km) and the Boat o'Brig
ALSTN (16.6 km). Figure 10 shows the mean distance progressed by each
group during the first 15 days after release. It is evident from the results
shown in Figures 9 and 10 that there are differences in the up-stream
progress of each monthly group.
Spring salmon ascending during February and March make less progress
during the first 15 days than those ascending during April, and this is also
reflected in the times taken by these groups to reach the Boat o'Brig
ALSTN. From Figure 10 it is evident that the salmon released during May
showed similar progress to those ascending during April; however, three of
the four salmon released during May returned to sea 10 or 11 days after