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May 1 through May 14, 2006, Report No.
8
Waterford:
The Waterford rotary screw
trap sampled 13 out of 14 days between May 1 and May 14. A
total of 29 juvenile Chinook salmon were captured,
increasing the season total to 8,117. Daily catch ranged
from 0 to 5 Chinook (Figure 1). Average forklength was 92.3
mm and ranged from 67 mm to 110 mm. Average weight was 9.7 g
and ranged from 4.5 g to 16.1 g.
We will continue to sample
intermittently throughout the remainder of the season if
catch numbers remain consistently low.
Figure 1. Chinook
salmon catch at Waterford versus flow at La Grange (LGN).
No O.
mykiss were captured in the rotary screw trap during
this sampling period.
Two trap efficiency tests were
conducted at Waterford using Chinook from the Merced River
Hatchery on May 6 and May 13 with a resulting efficiency of
0.0% from each of the releases (Table 1). A larger release
group (i.e. ~2,500 Chinook) will be used in the next release
in an attempt to get some recaptures.
Table 1. Trap efficiency
tests conducted at Waterford between May 1 and May 14,
2006.
|
Location |
Date |
Mark |
Number released |
Number recaptured |
Mean Length @ Release(mm) |
Mean Length @ Recapture (mm) |
Estimated
Efficiency |
Flow (cfs)
at LGN |
|
Waterford |
5/6/06 |
CFO |
778 |
0 |
72.9 |
- |
0% |
8,749 |
|
Waterford |
5/13/06 |
CFO |
1,581 |
0 |
78.4 |
- |
0% |
8,475 |
Grayson:
The Grayson rotary screw traps
sampled 13 out of 14 days between May 1 and May 14. A total
of 34 juvenile Chinook salmon were captured, increasing the
season total to 1,462. Daily catch ranged from 0 to 5
Chinook (Figure 2). Average forklength was 95.9 mm and
ranged from 38 mm to 109 mm. Average weight was 10.1 g and
ranged from 4.7 g to 12.5 g.
We will continue
to sample intermittently throughout the remainder of the
season if catch numbers remain consistently low.
Figure 2.
Chinook salmon catch at Grayson versus flow at Modesto (MOD).
No O.
mykiss were captured in the rotary screw trap during
this sampling period.
Two trap efficiency tests were
conducted at Grayson using Chinook from the Merced River
Hatchery on May 5 and May 12 with resulting efficiencies of
0.42% and 0.39%, respectively (Table 2).
Similar to Waterford, we will be increasing the size of the
release group (i.e. ~1,500) in an attempt to recover more
marked fish.
Table 2. Trap efficiency
tests conducted at Grayson between May 1 and May 14,
2006.
|
Location |
Date |
Mark |
Number released |
Number recaptured |
Mean Length @ Release(mm) |
Mean Length @ Recapture (mm) |
Estimated
Efficiency |
Flow (cfs)
at MOD |
|
Grayson |
5/5/06 |
CFY |
949 |
4 |
73.3 |
74.3 |
0.42% |
7,942 |
|
Grayson |
5/12/06 |
CFY |
1,285 |
5 |
81.8 |
76.6 |
0.39% |
7,534 |
Environmental Data:
Instantaneous water
temperature ranged between 49.0°F and 54.0°F at Waterford,
and between 53.0°F and 57.2°F at Grayson. Turbidity
fluctuated between 1.3 NTU and 2.1 NTU at Waterford, and
from 1.8 NTU to 3.5 NTU at Grayson. During the sampling
period, flows at La Grange ranged between 8,153 cfs and
8,850 cfs, while flows at Modesto ranged between 7,505 cfs
and 8,021 cfs.
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