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March 21 through April 3, 2005, Report No.
6
Oakdale:
A total of 2,136 juvenile
Chinook were captured between March 21 and April 3
increasing the season total to 186,708. Daily catch
fluctuated throughout the sampling period and ranged from 13
to 872 Chinook (Figure 1). Average forklength was 56.7 mm
and ranged from 30 mm to 89 mm. Average weight for captured
Chinook was 2.4 g and ranged from
0.8 g to 6.5 g.
Average forklength increased
by more than 14 mm and average weight increased by 1.6 g
since the previous sampling period. Similar to past years,
daily catch decreased significantly during the parr
lifestage (45 mm-79 mm). However, a three-day peak in catch
of 1,577 Chinook was observed following an increase in flow
and turbidity associated with a rain event.
Figure 1. Chinook
Catch at Oakdale versus flow at Orange Blossom Bridge.
Two
O. mykiss were
captured on March 24 and March 25 measuring 251 mm and 286
mm, respectively increasing the season total to 20 at
Oakdale. Both fish were retained and will be provided to
CDFG for analysis as part of a
Distribution and
Relationship of Resident and Anadromous Central Valley
Rainbow Trout project currently being conducted
by George Edwards at CDFG. Up to 30
O. mykiss
captured in the rotary screw traps during the 2005 season
will be provided to CDFG for their studies.
No trap efficiency releases were conducted during the
sampling period.
Caswell:
A total of 537 juvenile
Chinook were captured between March 21 and April 3
increasing the season total to 24,011. Daily catch ranged
from 15 to 163 Chinook (Figure 2).
Average forklength was 57.0 mm and ranged from 30 mm to 86
mm. Average weight for captured Chinook was 3.3 g and
ranged from 0.8 g to 6.6 g. Average forklength
increased by almost 12 mm and average weight increased by 1
g since the previous sampling period.
Figure 2. Chinook
Catch at Caswell versus flow at Ripon.
Four
O. mykiss were
captured during the sampling period increasing the season
total to 11 at Caswell. Three out of the four
O. mykiss were
captured on a single date (March 24). Refer to Table 1
below for data collected from each
O. mykiss
captured. Three fish were retained and will be provided to
CDFG for analysis as part of a
Distribution and
Relationship of Resident and Anadromous Central Valley
Rainbow Trout project.
Table 1.
Date, forklength, smolt index,
and weight of O. mykiss
captured at Caswell between March 24 and
March 25,
2005.
|
Date |
Forklength (mm) |
Smolt Index1 |
Weight (g) |
|
03/24/05
|
287* |
5
|
254.0 |
|
03/24/05
|
202* |
5
|
72.0 |
|
03/24/05
|
275 |
5
|
nd |
|
03/25/05 |
277* |
5
|
215.4 |
1Smolt index rating scale:
1-Sac-fry; 2-Fry; 3-Parr; 4-Silvery Parr; 5-Smolt; 6-Adult
Note: Fish with an
asterisk (*) indicate they were retained and will be
provided to CDFG.
Trap efficiency releases were
conducted on three nights between March 27 and April 1 and
results of releases are presented in Table 1. Estimated
trap efficiencies are consistent with past year's data based
on flow, turbidity and fish size.
Table 1. Release
and recapture data for trap efficiency conducted at
Caswell.
|
Date |
# Released |
# Recaptured |
Trap Efficiency |
Mean Length @ Release (mm) |
Mean Length @ Recapture (mm) |
Turbidity (NTU) |
Flow @ RIP |
|
03/27/05 |
312 |
46 |
14.7% |
70.9 |
59.1 |
7.2 |
621 |
|
03/29/05 |
161 |
12 |
7.5% |
67.7 |
63.5 |
6.0 |
702 |
|
04/01/05 |
102 |
10 |
9.8% |
72.4 |
70.9 |
6.4 |
408 |
Environmental Data:
Rain events caused environmental
conditions to fluctuate during the sampling period.
Instantaneous temperature fluctuated between 49°F
and 54°F
at Oakdale and between 54°F
and 59°F
at Caswell. Turbidity ranged from 1.9 NTU to 33.0 NTU at
Oakdale and from 2.6 NTU to 55.0 NTU at Caswell. During the
sampling period, flow releases from Goodwin Dam (GDW)
fluctuated between 229 cfs and 604 cfs. Releases from GDW
were increased to 600 cfs for a couple of days for flood
control purposes in Tulloch Reservoir. Flows at Orange
Blossom Bridge (OBB; RM 46.9) ranged from 241 cfs to 665 cfs
and at Ripon (RIP; RM 15.8) from 326 cfs to 878 cfs.
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