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May 12 through
June 4 , 2008; Report No.
5
Waterford:
The trap sampled continuously between May 12 and June 2. A total of
377 juvenile Chinook salmon were captured during the
sampling period increasing the season total to 3,333. Daily catch ranged from zero to 55 Chinook (Figure
1). Average forklength was 88.2 mm and ranged from 35 mm to
115 mm. Average weight was 7.7 g and ranged from 3.6 g to
12.8 g.
An O. mykiss (58 mm; 2.5 g) was captured in the rotary screw trap
on May 23 increasing the season total to nine.
Figure 1. Chinook
salmon catch at Waterford versus flow at La Grange (LGN).
One trap efficiency test was conducted at Waterford using natural Chinook captured from the trap with a resulting efficiency of 12.2%.
Table 1. Release and recapture data for trap efficiency
releases conducted at Waterford.
| Release Date |
# Released |
# Recaptured |
Trap Efficiency |
Mean at Release (mm) |
Mean at Recapture (mm) |
Flow at MOD (cfs) |
Turbidity (NTU) |
| 5/16/08 |
41 |
5 |
12.2% |
88 |
88 |
811 |
0.7 |
Instantaneous water temperature taken at the Waterford trap
ranged between 58.2 °F and 70.5 °F and turbidity ranged from
0.3 NTU to 4.4 NTU. Daily average flow at La Grange ranged between
86 cfs and 830 cfs. Releases from La Grange Dam were increased during the VAMP period (i.e., between April 19 and May 19, 2008).
Sampling at Waterford was terminated for the season on June 2.
Grayson:
The traps sampled continuously between May 12 and June 4. A total of six juvenile Chinook were captured increasing the season total to 185. Daily catch ranged from zero to two Chinook (Figure
2). Average forklength was 92.1 mm and ranged from 83 mm to
100 mm. Average weight was 8.4 g and ranged from 7.4 g to
9.6 g.
Figure 2. Chinook
salmon catch at Grayson versus flow at Modesto (MOD).
Two
trap efficiency tests were conducted at Grayson using fish from Merced River Hatchery on May 14 and May 21 with resulting efficiencies of 2.5% and 3.7%, respectively (Table 2).
Table 2. Release and recapture data for trap efficiency
releases conducted at Grayson.
| Release Date |
# Released |
# Recaptured |
Trap Efficiency |
Mean at Release (mm) |
Mean at Recapture (mm) |
Flow at MOD (cfs) |
Turbidity (NTU) |
| 5/14/08 |
519 |
13 |
2.5% |
93 |
91 |
941 |
3.98 |
| 5/21/08 |
515 |
19 |
3.7% |
92 |
91 |
678 |
2.75 |
Instantaneous temperature taken at the trap ranged between 62.0 °F and 71.4 °F, and turbidity ranged from 1.56 NTU to 6.78 NTU. Daily average flow at Modesto (MOD) fluctuated between 209 cfs and 1,040 cfs.
Sampling at Grayson was terminated for the season on June 4.
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